The Mars Apparition of 2019-2021
by Martin J. Powell
The path of Mars against the background stars from May 2020 to March 2021, shown at 10-day intervals (click on the thumbnail for the full-size image, 163 KB). During this apparition Mars described a 'zig-zag' shaped path against the stars, quite unlike the Southward-facing loop that it described during the planet's previous apparition in 2017-19. The paths of Uranus and Neptune are also shown for reference. Planetary conjunctions between Mars and Neptune and Mars and Uranus took place on June 12th 2020 and January 21st 2021 respectively (marked on the chart by the symbol ). For more details on these and conjunctions involving other planets, see the planetary conjunctions section below.
The star map applies to observers in the Northern hemisphere (i.e. North is up); for the Southern hemisphere view, click here (167 KB) The faintest stars shown on the map have an apparent magnitude of about +4.8. Printer-friendly versions of this chart are available for Northern (76 KB) and Southern hemisphere (77 KB) views. Astronomical co-ordinates of Right Ascension (longitude, measured Eastwards in hrs:mins from the First Point of Aries) and Declination (latitude, measured in degrees North or South of the celestial equator) are marked around the border of the chart. Click here (119 KB) to see a 'clean' star map of the area (i.e. without planet paths); a printable version can be found here (59 KB). Photographs of this region of the night sky can be seen below.
The four star names shown in yellow-green were officially adopted by the International Astronomical Union (IAU) in 2017.
At superior conjunction on September 2nd 2019 (when it passed directly behind the Sun in the constellation of Leo, the Lion), Mars was positioned 2.6747 Astronomical Units (AU) from Earth (400.1 million kms or 248.6 million miles). Were it to have been visible from Earth at this time, its apparent magnitude would have been +1.7 and its apparent size only 3".5 (i.e. 3.5 arcseconds, where 1" = 1/60th of an arcminute or 1/3600 of a degree). Mars entered the constellation of Virgo, the Virgin, on September 24th, becoming visible in the dawn twilight from Northern Tropical latitudes in early October. The planet moved to the South of the celestial equator (where the declination of a celestial body is 0°) on October 7th, becoming visible from Equatorial and mid-Northern latitudes over the coming days.
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Mars passed 28' (28 arcminutes or 0°.5) South of the star Zaniah ( Vir or Eta Virginis, mag. +3.8), in central Western Virgo, on October 12th, the star being visible at dawn only from Northern hemisphere latitudes at this time of year. The 2019-21 apparition truly got underway as the planet reached a solar elongation (angular distance from the Sun) of 15° West on October 17th. The Red Planet was slowly pulling away Westwards from the Sun at a rate of just 0°.3 per day at this time. By the third week of October Mars had become visible from higher Northern latitudes and as far South as the Southern Tropics, rising in the East between 45 minutes (15° South) and 1½ hours (60° North) before sunrise. From latitudes South of the Southern Tropics, low altitude (angle above the horizon) and twilight delayed the appearance of Mars until early November (35° South) and late November (45° South).
At this early stage in the apparition, Mars appeared as a feeble, pale-orange 'star', shining about as bright as the star Castor ( Gem or Alpha Geminorum, mag. +1.6) in the constellation of Gemini, the Twins. Mars barely gained any significant altitude before disappearing into the brightening dawn twilight. Telescopically it was a disappointing sight, its tiny apparent size frustrating most attempts to obtain a clear view of the planet's surface.
A Martian Dust Storm over the Mare Acidalium in the planet's Northern hemisphere, imaged by John Boudreau (Saugus, MA, USA) in late May 2018 (click on the thumbnail for a larger image, 5 KB). This was one of the first images to capture the event, which over the next month became a global dust storm. Boudreau used a 368mm (14½-inch) Dall-Kirkham telescope fitted with a CMOS camera (Image: John Boudreau / ALPO-Japan).
On October 21st Mars passed 2º.0 South of the double star Porrima ( Vir or Gamma Virginis, mag. +3.5), which prior to International Astronomical Union (IAU) standardisation in 2016 was sometimes known by the name of Arich. At this time of year the star is only visible from the Northern hemisphere and as far South as the Southern Tropics. The same is true for the star Vir (Theta Virginis, mag. +4.4) in central Virgo, which Mars passed 1º.0 to the South of on November 2nd. The Red Planet passed 3°.1 North of Virgo's brightest star Spica ( Vir or Alpha Virginis, mag. +1.0) on November 8th.
By mid-November Mars had reached 25° West of the Sun and was rising in darkness from across the Northern hemisphere. The planet now rose 2¾ hours ahead of the Sun at latitude 60° North, 1 hour before the Sun at latitude 40° North and 1½ hours before sunrise at the Equator and Southern Tropical latitudes. At mid-Southern latitudes Mars rose in twilight about an hour before sunrise. The planet's position in South-eastern Virgo, around 10° South of the celestial equator, meant that it rose in the East from latitudes South of the Northern Tropics and in the ESE from latitudes North of the Northern Tropics. Before disappearing from view in the brightening dawn sky, Mars attained an altitude of 14° at latitude 60° North, 20° at 40° North, 21° at the Equator and 11° at 35° South.
In mid-November the planet Mercury (magnitude +0.7), having recently transitted the Sun, entered the dawn sky in its third and final morning apparition of 2019. This particular apparition favoured Northern hemisphere viewers because of the planet's higher altitude in the Eastern sky at dawn. Mercury approached Mars from the East, reaching its Western stationary point in Libra, the Balance or Scales, on November 20th. Mercury, having brightened to mag. -0.1, came to within 9º.5 of Mars on November 23rd before its retrograde (East to West) motion began to carry it back towards the Sun. Mercury became lost from view in the dawn twilight between mid-December (higher Northern latitudes) and late December (elsewhere).
On November 27th Mars passed 2°.3 South of the star Kang ( Vir or Kappa Virginis, mag. +4.2), which is located in South-eastern Virgo. In Chinese astronomy Kang was both a constellation and a name given to the second of 28 lunar mansions. The name was formerly adopted in 2017 by the Working Group on Star Names (WGSN), a newly-established division of the IAU which since 2016 has been cataloguing and standardizing the star names used by the international astronomical community. In order to accommodate a wider diversity of global culture, the WGSN has adopted some names from mythologies other than Arab, Greek and Roman, whose star names dominate the night sky. Mars passed several other 'newly-named' stars during its 2019-21 apparition, many of which will be discussed below, along with a number of better-known star names (proper names) for which the IAU have now introduced standardized spellings.
At around 0430 UT on November 30th Mars passed just 9'.5 (0°.16) North of the star Vir (Lamba Virginis, mag. 4.5), which is positioned at the far South-eastern side of the constellation, only 39' (0°.65) from the border with Libra. The planet entered Libra itself on December 1st.
At around 1015 UT on December 12th the Red Planet passed 13' (0°.2) North of the double star Zubenelgenubi (2 Lib or Alpha2 Librae, mag. +2.8), which on older star maps was depicted as the top of Scales' balancing point. The star comprises a blue-white component of magnitude +2.7 (2 Lib) and a white companion of magnitude +5.2 (1 Lib), separated in the night sky by a distance of 3'.8 and easily resolved in binoculars. On December 17th Mars passed 8º.5 North of the star Brachium ( Lib or Sigma Librae, mag. +3.3), the Southernmost star of the Scales' easily recognised quadrilateral figure.
On December 22nd Mars passed 8º.2 South of the star Zubeneschamali ( Lib or Beta Librae, mag. +2.5), the Northernmost star of the quadrilateral figure. It is said to have a greenish hue when viewed with optical aid - one of the very few stars in the night sky which appears this colour.
Mars passed 4°.0 South of the star Zubenelhakrabi ( Lib or Gamma Librae, mag. +3.9) on December 28th, the Easternmost star of the quadrilateral. Before IAU standardisation in 2017 the name was alternatively spelled Zuben Elakrab.
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By early January Mars was rising in darkness from most of the inhabited world, its solar elongation having extended to 42°W. The Red Planet now rose 3½ hours before the Sun at latitude 60º North, 3¼ hours before the Sun at 40º North and 3 hours before sunrise from latitudes South of the Northern Tropics. Mars rose in the ESE from all except higher Northern latitudes, from where it rose in the South-east. At 60° North the planet attained 10° altitude before the dawn twilight enveloped it, whilst at 40° North the planet attained an altitude of 24°. At the Equator it reached 39° whilst at 35° South it reached 31° high.
On January 4th Mars passed 3°.2 South of the star Lib (Theta Librae, mag. +4.1), positioned near the Eastern border of Libra. On January 6th the Red Planet passed 5º.9 North of the star Fang ( Sco or Pi Scorpii, mag. +2.8), located in the neighbouring constellation of Scorpius, the Scorpion - or more precisely, at the front end of the Scorpion. The name was formally assigned to the star by the IAU in 2017 after the fourth lunar mansion in ancient Chinese astronomy. In ancient China the four stars that we now consider to form the head of the Scorpion (1 Sco, Sco, Sco and Sco) were known as Fáng (‘Room’), the name of Sco in particular (Fáng Xiù) translating as "the First Star of Room". Later on the same day Mars passed 2º.3 North of the star Dschubba ( Sco or Delta Scorpii, mag. +2.3), also in Scorpius. Dschubba, an Arabic name meaning 'forehead', unexpectedly brightened in the year 2000 as it ejected a shell of gas, though it has long since faded.
Mars entered Scorpius on January 7th, passing 43' (0º.7) South of the double star Acrab (1 Sco or Beta-1 Scorpii, combined mag. +3.9), formerly known as Graffias, on the following day (8th). Its two blue-white components (1 Sco and 2 Sco) are magnitudes +2.6 and +4.9, separated by 13".7 and easily seen in small telescopes. Beta-1 Scorpii is itself also double, having a tenth-magnitude companion positioned less than an arcsecond away, separable only in larger telescopes.
Table showing the position and apparent magnitude of Mars for the early part of the 2019-21 apparition (click on the thumbnail for the full-size table, 22 KB). The magnitudes, diameters and solar elongations listed here refer to the middle of the period in question. In this and the tables which follow, the rising and setting directions of the constellations listed can be found by referring to the zodiacal constellation rise-set direction table.
On January 9th Mars passed a short distance North of the two Omegan stars Jabhat al Akrab (1 Sco or Omega-1 Scorpii, mag. +3.9) and 2 Sco (Omega-2 Scorpii, mag. +4.3). The two stars are separated in the night sky by 0º.24 and, together with the stars Jabbah ( Sco or Nu Scorpii, mag. +4.0) to their North-east, Acrab to their NNW and Dschubba to their South-west, they form an eye-catching asterism (star pattern) in the Northern region of the Scorpion. Mars' passage of the Omegan stars took around five hours, the planet passing 3'.5 (0º.06) North of 1 Sco at 0530 UT and 13'.8 (0º.23) North of 2 Sco at 1034 UT. Mars passed 1º.4 South of the aforementioned Jabbah, a multiple star with brighter components of magnitude +4.0 and +6.3, on January 11th.
On January 12th Mars reached magnitude +1.5, making it a first magnitude object. At around 2015 UT on the same day the planet passed 1º.9 North of the eighth-magnitude globular cluster Messier 80 or M80 (NGC 6093) which, like most of the brighter globulars, appears as a faint, circular, fuzzy spot of light through binoculars under dark skies. The narrow separation between the two objects means that binocular users are able to see the planet and cluster appear in close proximity. On January 14th Mars passed 4º.3 North of the variable star named Alniyat ( Sco or Sigma Scorpii, mag. +2.9v), positioned at the 'heart' of the Scorpion. The planet entered the constellation of Ophiuchus, the Serpent-Bearer or Serpent Holder, shortly after midnight UT on January 15th.
On January 17th Mars passed 4º.8 North of the Scorpion's brightest star Antares ( Sco or Alpha Scorpii, mag. +1.0v), a red supergiant which is at least 400 times the size of our Sun! The star twinkles (scintillates) with a distinct orange-red hue, rivalling the colour of the Red Planet. Indeed, the name Antares derives from the ancient Greek 'anti Ares' meaning 'rival of Mars' (Ares being the ancient Greek god of War). The brightness of the two celestial bodies differed at this passage by just 0.1 magnitude (Antares being the brighter of the two), which allowed for a good naked-eye comparison of their colours.
Over the following two weeks Mars passed North of five stars which were formally assigned 'new' names by the IAU in 2017 and 2018. Four of them are located in the tail of Scorpius and one - the faintest of the five - is in Southern Ophiuchus. On January 19th Mars passed 6º.4 North of the star Paikauhale ( Sco or Tau Scorpii, mag. +2.8), which is a Hawaii'an name for a vagabond. On January 24th the planet passed three of the newly-named stars: 12º.0 North of Larawag ( Sco or Epsilon Scorpii, mag. +2.2) at around 06 hours UT; 15º.7 North of Xamidimura (1 Sco or Mu-1 Scorpii, mag. +2.9) at 21 hours UT and, only moments later, 15º.7 North of Pipirima (2 Sco or Mu-2 Scorpii, mag. +3.5). Larawag is positioned about half-way along the Scorpion's tail and is an Aboriginal name derived from the Wardaman culture of Northern Australia; it means 'signal watcher'. Xamidimura and Pipirima are located 3º.5 South of Larawag, also in the Scorpion's tail. The two stars are separated in the night sky by just 5'.7 (0º.1), making them appear as a double star, however this is a line-of-sight effect and they are not physically related. Xamidimura is an eclipsing binary of the Beta Lyrae variable star type whilst Pipirima is a blue-white subgiant star. Xamidimura is the historical name given to the star by the Khoikhoi people of South Africa; it means 'eyes of the lion'. The name Pipirima comes from Polynesian mythology. It refers to a Tahitian story of two inseparable twins (Pipirima and Réhua) who fled from their parents and became stars in the night sky.
On January 31st Mars passed 7º.1 South of the star Sabik ( Oph or Eta Ophiuchi, mag. +2.5), the second brightest star in Ophiuchus. The name is Arabic and translates as 'the preceding one'. On February 1st the planet crossed to the South of the ecliptic (the path of the Sun, which the Moon and planets follow very closely) and later that day passed 3º.6 North of the star Guniibuu (36 Oph A or 36 Ophiuchi A, mag. +5.1), the fifth star assigned a 'new' name by the IAU in this region of the night sky. It is an Australian Aboriginal name meaning a robin red-breast, derived from Euahlayi-Kamilaroi culture. Guniibuu is one component of a pair of orange dwarf stars (A and B) which are easily split in small telescopes. As of mid-2019, four other Aboriginal names have been assigned to stars by the IAU. They are: Ginan, Wurren and Gudja (from Wardaman culture) and Unurgunite (from Boorong culture); these apply to the stars Epsilon Crucis, Zeta Pheonicis, Kappa Serpentis and Sigma Canis Majoris, respectively.
On February 4th Mars passed 1º.9 North of Ophiuchus' Southernmost bright star Oph (Theta Ophiuchi, mag. +3.2). On older star maps the stars Oph and Guniibuu were depicted as marking the ankle of the Serpent-Bearer.
To the South of Ophiuchus the Scorpion's tail curves around to the East and North-east, deep within an area rich in Milky Way galaxy stars. Mars passed 14º.1 North of the star Lesath ( Sco or Upsilon Scorpii, mag. +2.6) on February 7th and 13°.8 North of the star Shaula ( Sco or Lambda Scorpii, mag. +1.6) on February 8th. Together these two stars form the 'sting' at the end of the Scorpion's tail.
On February 9th Mars passed 8º.0 South of the star Ser (Xi Serpentis, mag. +3.5), positioned 6º.5 to the East of the aforementioned Ophiuchan star Sabik and at the South-eastern corner of a trapezoidal arrangement of third and fourth-magnitude stars. Located in the constellation of Serpens Cauda, the Serpent's Tail, the other two stars are Ser (Omicron Serpentis, mag. +4.2) at the North-eastern corner of the trapezoid and Ser (Nu Serpentis, mag. +4.3) at the North-western corner. This is, of course, the tail section of the serpent, of which the Serpent-Bearer (namely, the Greek god Asciepius or Aesculapius) is holding. Mars left Ophiuchus and entered the Southernmost zodiac constellation of Sagittarius, the Archer, on February 11th.
On February 13th Mars passed 13º.5 North of another star in Scorpius' tail to be assigned a 'new' formal name by the IAU - in this case, in the year 2017. Fuyue (G Scorpii, mag. +3.2) is positioned at the tail-end of the Scorpion. Fu Yue was a Chinese labourer who became a wise minister and a chancellor of the Emperor Wu Ding (ca. 1250-1192 BC) of the Shang dynasty. After Fu Yue's death he is said to have become part of a constellation known as The Sieve, situated in the Tail mansion (Wei Xiù) in ancient Chinese astronomy.
Over the course of 31 hours from February 17th to 18th Mars passed less than 1º to the North of the gaseous nebula M8 (NGC 6523), also known as the Lagoon Nebula. With apparent dimensions of 90' by 40' and an integrated magnitude (i.e. its apparent magnitude if the cluster were concentrated into a single point) of about +5 it is visible to the naked eye as a hazy patch of light under truly dark skies. Telescopes reveal a dark lane through its centre and a star cluster (NGC 6530) in the Eastern half of the nebula, comprising around two dozen stars of 7th magnitude and fainter. The Red Planet began its passage of M8 from around 14 hours UT on the 17th and ended it at around 21 hours UT on the 18th.
Positioned a short distance to the NNW of M8 is another gaseous nebula - M20 or NGC 6514 - also known as the Trifid Nebula. Its brightest region is roughly elliptical in shape and measures 29' by 27'. Seen through telescopes under dark skies, three dark dust lanes can be seen, from which the nebula gets its name. At the centre of the nebula is a double star comprising components of 7th and 8th magnitude. Mars passed less than 1º to the South of M20 over the course of seven hours from 16 hours UT on the 17th to 23 hours UT on the same day. The Red Planet was positioned roughly mid-way between M20 and M8 at around midnight UT on February 18th.
Also on February 18th, Mars was involved in a lunar occultation, one of six such events which took place during the course of the Martian 2019-21 apparition. A lunar occultation occurs when the Moon passes in front of the planet, blocking it from view for a short period of time. Because of the rotating Earth, the relative closeness of the Moon to the Earth and the consequent effect of parallax, any given lunar occultation can only be observed from a particular region of the world. The February 18th occultation took place from around 13 hours UT and was visible in darkness and/or twilight from central and Western USA (not Alaska and Hawaii), central and Western Canada (not North-western British Columbia, Yukon Territory or the North-west Territories) and Mexico. The occultation took place whilst both Mars and the waning crescent Moon were positioned just to the North of the Lagoon Nebula. For a map and timings of this event, follow the link provided in the Moon near Mars section below.
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Also commencing on February 18th, Mars passed to the North of the so-called Teapot asterism in South-western Sagittarius. Seen in a North-up orientation, the stellar teapot appears 'tipped up', pouring its contents South-westwards into neighbouring Scorpius. The Teapot extends from the star Alnasl ( Sgr or Gamma Sagittarii, mag. +3.0) in the West to the star Tau Sagittarii ( Sgr, mag. +3.3) in the East. The planet's asterism passage lasted for three weeks, ending on March 10th. Mars passed 6º.8 North of Alnasl, at the front of the Archer's bow, on February 18th. Prior to IAU standardisation in 2016 the star was commonly known as Nash.
On February 20th Mars attained its most Southerly declination for this apparition, at -23° 40' 11" (-23°.6698 in decimal format) in Western Sagittarius. Across the inhabited world the planet now rose at its most Southerly point on the local horizon. Typically this will be towards the South-east at latitudes far away from the Equator and towards the ESE at Equatorial latitudes. The planet's high-Southern declination dramatically affected the duration which it spent above the horizon at any given latitude. Mars now rose two hours ahead of the Sun at 60º North, 3¼ hours before the Sun at 40º North, four hours before sunrise at the Equator and 4¾ hours before sunrise at 35º South.
On February 21st Mars passed 2º.5 South the star Polis ( Sgr or Mu Sagittarii, mag. +3.8v), positioned just to the North-west of the Teapot. It is an eclipsing binary star with a tiny brightness variation of ±0.1 magnitudes. Although not part of the Teapot, it is sometimes considered to be included in an older asterism called the Milk Dipper, which is envisaged as a ladle dipping into the rich Milky Way.
Mars passed 6º.3 North of the star Kaus Media ( Sgr or Delta Sagittarii, mag. +2.7), positioned at the centre of the Archer's bow, on February 23rd. Before IAU standardisation in 2016 it was also known by the names Kaus Meridionalis and Kaus Medius. On February 24th the planet passed 10º.8 North of Sagittarius' brightest star Kaus Australis ( Sgr or Epsilon Sagittarii, mag. +1.8), positioned at (or near) the Southern tip of the Archer's bow. On February 26th the planet passed 1º.8 North of the star Kaus Borealis ( Sgr or Lambda Sagittarii, mag. +2.8) which marks the top of the Teapot asterism. The name Kaus is Arabic for 'bow', its Northern and Southern sections (Borealis and Australis) being later Latin additions.
At around 2330 UT on February 28th Mars passed 20' (0º.33) North of the relatively bright globular cluster M22 (NGC 6656) which is considered to be one of the finest globulars in the night sky. Its integrated magnitude is about +5.9 and it has an apparent diameter of 24'. It is just visible to the naked-eye from dark sites, is easily seen through binoculars and is a spectacular sight through telescopes.
From late February Mars began to rise in twilight once more from higher Northern latitudes. From these locations the high Southerly declination of the planet and the shallow rising angle to the local horizon meant that the planet gained very little altitude before twilight enveloped it. With the lengthening days of Spring and Summer now approaching, the twilight would not begin to recede from these latitudes until around mid-August, severely restricting views of the planet during the intervening months.
At 1611 UT on Leap Year Day (February 29th) Mars passed a mere 2'.6 (0º.043) South of the star BSC 6990 (mag. +5.8) in central-Western Sagittarius. The star - which is close to the limit of naked-eye detection - is also known by the designations HIP 91405, SAO 187080 and TYC 6858-01156-1, among others. Mars will occult (pass in front of) this star in March 2035.
March began with Mars positioned in central Sagittarius. Over the next week the planet passed the four stars which form the 'handle' of the Teapot: 3°.5 North of Sgr (Phi Sagittarii, mag. +3.1) on March 3rd; 3°.0 North of the constellation's second-brightest star Nunki ( Sgr or Sigma Sagittarii, mag. +2.0) on March 6th; 6°.7 North of Ascella ( Sgr or Zeta Sagittarii, mag. +2.6) on March 8th and finally, 4º.5 North of Sgr (Tau Sagittarii, mag. +3.3) on March 10th. Having left the bulk of the brighter stars of Sagittarius behind it, Mars continued on its Eastward course, passing 1°.9 South of Albaldah ( Sgr or Pi Sagittarii, mag. +2.9), one of three stars marking the Archer's head, on March 11th. It is a multiple star whose Arabic name apparently means 'the town'.
In recent weeks Mars had been slowly approaching the giant planets Jupiter and Saturn in the night sky, both now positioned in North-eastern Sagittarius. Jupiter entered the constellation in November 2019 and was only about two weeks into its 2020-21 apparition. Saturn had been in Sagittarius since 2017 and was about 1½ months into its 2020-21 apparition. In mid-March Mars (mag. +0.9) was gaining on a slower-moving Jupiter at a rate of 0°.5 per day. At midnight UT on March 12th Jupiter (mag. -1.8) was positioned 4°.5 to the ENE of Mars; on the 14th the King of the planets was 3°.5 to the ENE of the Red Planet; on the 16th it was 2°.5 to the ENE of Mars and on the 18th it was 1°.5 to the North-east of it. Saturn (mag. +0.6) was positioned 12°.2 to the ENE of Mars on March 12th and 8°.5 to the ENE of it on March 18th. The waning crescent Moon passed to the South of the three planets on March 18th and 19th, being particularly nicely placed between 16 and 17 hours UT on the 18th - a grouping best seen from Oceania at dawn (March 19th local time).
Also on the 18th, Mars was involved in the second lunar occultation of the apparition - although the event was only visible from a sparsely populated region of the world. From around 08 hours UT the waning crescent Moon occulted the Red Planet, visible in darkness from the Southern tip of South America (Southern Argentina and Southern Chile), Drake Passage and part of Antarctica. At 0935 UT Mars, Jupiter and the Moon formed a close grouping within just 1°.5, one of only three such tight trios (within 2°) to take place between these three celestial bodies during the 21st century. The grouping was best seen just before dawn from Northern Chile and Southern Peru.
The North-eastern region of Sagittarius, through which Mars travelled over the following four weeks, has numerous stars of 4th magnitude or fainter. Amongst them is the star 52 Sgr (52 Sagittarii, mag. +4.6), which on older star maps is shown positioned at the 'rump' of the centaur figure. Mars passed 2°.5 to the North of 52 Sgr at around 0230 UT on March 20th.
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At 0620 UT on March 20th Mars and Jupiter met in the first of six planetary conjunctions which took place during the planet's 2019-21 apparition. A planetary conjunction occurs whenever any two planets attain the same celestial longitude, such that they appear close together in the night sky. In this instance the pair were separated by an apparent distance of 0°.7 and the solar elongation was 67°. The conjunction was well placed for Southern hemisphere observers but poorly placed for those at higher Northern latitudes. The two planets were easily contained within a wide-field telescope field of view, Mars having increased in apparent size to 6" (but small nonetheless) and Jupiter, six times larger at 36" across, providing a contrasting visual treat. Over the next 17 months Mars would pass each of the remaining Solar System planets in the course of its journey through the zodiac. For more details, refer to the planetary conjunctions section below.
A few hours after the conjunction, at around 11 UT on March 20th, Mars and Jupiter formed a right-angled triangle with Saturn 7°.1 to the ENE, Jupiter being at the 90° angle. The triangle pointed ENE towards the constellation of Capricornus, the Sea-Goat. Saturn itself crossed the Sagittarian boundary and entered Capricornus on March 21st.
At around 12 hours UT on March 26th, Mars positioned itself between, and slightly to the South of, Jupiter and Saturn, forming an isosceles triangle with long side 6°.6 (Jupiter-Saturn) and short sides 3°.4. The two giant planets were placed only fractionally South of the ecliptic whilst Mars was 0°.8 to the South of it. This 'planetary trio' was the closest grouping between these three planets since April 2000, when they came to within 5°.2 of each other in the constellation of Aries, the Ram. Their next closest grouping will be in August 2040 when they will come to within 6°.3 of each other in Virgo.
Located at the central Eastern end of Sagittarius are a group of four 4th-magnitude stars, within 2° of each other, named the Terebellum. The name is a Latin translation of an original Greek word meaning 'four-sided figure', allotted to this star group by Claudius Ptolemy (ca. 100-170 AD) in his famous star catalogue, the Almagest. The Terebellum comprise the stars Sgr (Omega Sagittarii, mag. +4.7), 59 Sgr (mag. +4.7), 62 Sgr (mag. +4.5) and 60 Sgr (mag. +4.8). Mars passed between 5° and 6° North of the group between March 26th and 28th.
At 1830 UT on March 29th the distance between the Earth and Mars was the same as that between the Sun and Mars, at 1.4784 AU (221.1 million kms or 137.4 million miles). Seen from far above the Earth's North pole, the Earth, Mars and the Sun now appeared to form an isoscelene triangle in space, with Mars positioned at the apex.
Mars continued its approach Eastwards towards a slow-moving Saturn, gaining on the ringed planet by 0°.6 per day. At midnight on March 29th Saturn was positioned 1°.9 to the North-east of Mars, 1°.4 North-east of the Red Planet on the 30th and 1°.0 NNE of it on the 31st. Mars entered Capricornus on March 30th.
At 11 hours UT on March 31st Mars passed 0º.9 South of Saturn in the second planetary conjunction of the 2019-21 apparition. Coming only 11 days after its conjunction with Jupiter, this event was also best observed from the Southern hemisphere. Saturn's rings were still nicely presented to the Earth, although the planet would not be seen at its best until July. At this time Saturn's globe, whose North pole was tilted in our direction, appeared 16" across whilst the rings were 36" across. By comparison, the Martian disk appeared just 6".4 across, 2½ times smaller than the globe of Saturn. At 1720 UT on the same day Mars, Saturn and Jupiter formed a right-angled triangle with Saturn at the 90º angle and Jupiter 6º.3 to the WSW of the pair. The triangle pointed WSW, back towards Northern Sagittarius.
As April began, Mars left the giant planets behind it and proceeded through the constellation of Capricornus. On April 3rd Mars passed 8º.1 South of the star Algedi (2 Cap or Alpha-2 Capricorni), an apparent naked-eye double star with Prima Giedi (1 Cap or Alpha-1 Capricorni, mag. +4.2). Prior to IAU standardisation in 2016 Algedi was also known by the name Secunda Giedi. The stars are not physically related, since they lie at very different distances from the Earth; the closeness of the two stars is therefore a line-of-sight effect.
Mars passed 5º.7 South of another double star, Dabih (1 Cap or Beta-1 Capricorni, mag. +3.1), on April 4th. It is a yellow star with a blue companion of magnitude +6.1, positioned 3'.5 to the West, visible in binoculars and small telescopes. On April 19th the planet passed 48' (0º.6) South of Cap (Theta Capricorni, mag. +4.0), which is positioned at the centre of the constellation. Mars reached magnitude +0.5 on April 24th, technically making it a zeroth-magnitude object. The following day at 15 hours UT Mars passed 8' (0°.13) South of the star Cap (Iota Capricorni, mag. +4.2), which is positioned at the 'rump' of the Sea-Goat figure.
Table of selected data relating to the brighter part of the Mars apparition of 2019-21 (click on thumbnail for full-size table, 144 KB). The data is listed at 10-day intervals, corresponding with the dates on the star map.
The Central Meridian Longitude (provided for telescopic observers) is the Martian longitude which appears at the centre of the disk when seen from the Earth at the time indicated (0h Universal Time, or 0h GMT). A Martian longitude map by Damian Peach showing the surface features can be seen at the ALPO-Japan website (note that the map is shown with South up, matching the inverted view seen through astronomical telescopes). For example, when CM = 290°, Syrtis Major appears at the centre of the disk. The Central Meridian Longitude increases by 14°.6 every hour, so this allowance should be applied for observations at other times (if the result is greater than 360°, subtract 360° to obtain the correct longitude).
Those wishing to observe Mars telescopically should consider downloading the free 'Mars Previewer II ' software by Leandro Rios, available as a ZIP file at Sky & Telescope, or Kyle Edwards' 'Solar System Imaging Simulator'.
The data for the table was obtained from 'RedShift 5', ''SkyGazer Ephemeris' , 'Mars Previewer II' software and the SETI Institute's Mars Ephemeris Generator 2.6. The Martian disk images were derived from NASA's Solar System Simulator. The Martian disks appear at the same scale as those in the Mars Opposition data table here.
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Located several degrees to the North of Mars was the Western half of the constellation of Aquarius, the Water Carrier. Its brightest star is Sadalsuud ( Aqr or Beta Aquarii, mag. +2.9), a name which is Arabic for 'the lucky one of the lucky', its meaning having astrological origins. Some 2º.7 to the South-east of Sadalsuud is the binary star Bunda ( Aqr or Xi Aquarii, mag. +4.7), a name formally assigned by the IAU in 2018 after a Persian lunar mansion. Mars passed 10º.7 South of Sadalsuud on April 28th and 7º.9 South of Bunda on May 1st.
The planet passed 1°.0 North of Nashira ( Cap or Gamma Capricorni, mag. +3.7) on May 2nd and 0°.9 North of Deneb Algedi ( Cap or Delta Capricorni, mag. +2.9), the brightest star in the constellation, on the 4th. Deneb Algedi is Arabic for 'tail of the goat' and it was also known as Deneb Algiedi or Scheddi before IAU standardisation in 2017.
Mars entered the star chart coverage (above) on May 5th, positioned 2º West of the Capricornian border with Aquarius. The planet passed 13º.2 South of the constellation's second-brightest star Sadalmelik ( Aqr or Alpha Aquarii, mag. +2.9) at 1450 UT on May 11th, then 13' (0°.21) North of the star Aqr (Iota Aquarii, mag. +4.2), at the 'knee-joint' or 'hip' of the Water Carrier (depending upon the star map depiction) at 1950 UT on the same day. Mars passed 4º.9 South of the star Ancha ( Aqr or Theta Aquarii, mag. +4.1), in central Aquarius, on May 15th.
From May 17th to 22nd the Red Planet was positioned about 11º South of Aquarius' best-known naked-eye feature, the so-called 'Steering Wheel' asterism. On older star maps it marked the amphora from which the Waterman poured his water, though on more recent star maps it sometimes appears as the Waterman's head. At the centre of the 'wheel' is the star Aqr (Zeta Aquarii, mag. +3.7) with the stars Sadachbia ( Aqr or Gamma Aquarii, mag. +3.9), Aqr (Eta Aquarii, mag. +4.0) and Aqr (Pi Aquarii, mag. +4.8) encircling it. It is one of several asterisms in the zodiac with which beginner astronomers should become familiar. Mars passed 10º.9 South of Sadachbia on May 17th and the same distance South of Aqr - at the Eastern edge of the 'wheel' - on May 22nd. The planet passed 3º.6 North of the star 2 Aqr (Tau-2 Aquarii, mag. +4.0) on May 28th and 2º.0 South of the star Aqr (Lambda Aquarii, mag. +3.9) on May 29th. On May 30th Mars passed 6º.4 North of the star Skat ( Aqr or Delta Aquarii, mag. +3.2) which on old star maps marked the Waterman's lower right leg.
Far to the South of Mars in May and June was the constellation of Piscis Australis, the Southern Fish. Ancient Greek and Babylonian mythology describes it as being the parent of the much more famous zodiacal Pisces and it was envisaged as drinking the water poured from the Waterman's amphora. The constellation's brightest star is Fomalhaut ( PsA or Alpha Piscis Austrini, mag. +1.2), a blue-white star whose Arabic name translates as the 'fish's mouth'. With a declination of -29º.6 it cannot be seen North of latitude 60º.4 North. Even at mid-Northern latitudes the star's altitude at meridian transit is low, reaching just 10º above the Southern horizon at 50º North and 20º above the horizon at 40º North. From the Northern hemisphere the star shines in splendid isolation, being the brightest star for some distance around it. Mars passed 20º.6 North of Fomalhaut on May 31st but the star was a prominent object to the South of the Red Planet throughout its passage of Aquarius.
By late May twilight was beginning to interfere with observation of Mars from as far South as 50º North latitude, caused by the lengthening daylight hours of the approaching midsummer. The twilight would begin to recede from these latitudes from around mid-July.
A Gibbous Mars sketched by David Gray (Spennymoor, UK) in April 2018 using a 415mm (16.3-inch) Dall-Kirkham Cassegrain telescope at 270x magnification (click on the thumbnail for a larger image, 4 KB). Mars was only a few days from its minimum phase of 87% in the morning sky and measured 9".1 in diameter (Image: David Gray / ALPO-Japan).
At 09 hours UT on June 2nd Mars was positioned at precisely 1.0000 AU from the Earth, i.e. the same distance as the average distance of the Earth from the Sun (149.5 million kms or 92.9 million statute miles). Viewed from a point in space far above the Earth's North pole, the Earth, Mars and the Sun would now have appeared to form an isosceles triangle, with Earth positioned at the apex.
On June 6th Mars reached Western quadrature, when it was positioned 90° West of the Sun. The Martian disk now appeared 9".6 across and it shone at magnitude -0.1. Theoretically, when seen from the Earth, Mars would now have shown its minimum illuminated phase, such that it would have appeared significantly gibbous when seen through telescopes (in this case, 84.6% illuminated). However, the eccentric nature of the Martian orbit is such that true minimum phase would not occur until June 19th, by which time its phase would have reduced slightly further to 84.3%. At Western quadrature Mars was rising just 1¾ hours before sunrise at latitude 60° North, four hours before sunrise at 40° North, 5½ hours before the Sun at the Equator and 7¼ hours before the Sun at 35° South. Directionally, Mars rose towards the ESE at mid- and high Northern latitudes and towards the East at latitudes further South. At latitudes North of 16° South, the planet had not yet reached the local meridian as it disappeared from view in the dawn twilight; to the South of 16° South the planet had already crossed the local meridian when it disappeared from view.
On June 7th Mars passed 1°.6 South of the star Aqr (Phi Aquarii, mag. +4.2), which on older star maps is one of several stars which marked the stream of water which flowed from the Waterman's amphora; more recent maps have shown it marking the top of his amphora. Later that same day the planet passed 1°.6 North of the star 1 Aqr (Psi-1 Aquarii), also magnitude +4.2, another star in the water stream. Mars was positioned precisely between Aqr and 1 Aqr at 13 hours UT on June 7th.
Between 1724 UT and 1736 UT on June 8th Mars occulted an eighth-magnitude star in Eastern Aquarius. The star has the Tycho catalogue designation TYC 5249-00975-1 and shines at magnitude +8.4. The occultation was not visible to the naked-eye but it was visible through small telescopes from Australia, Indonesia, Oceania and the Northern part of New Zealand. A star map showing the path, visibility zone and timings of the event can be seen at the Belgian VVS website.
Between June 8th and 20th, Mars was positioned several degrees South of the Circlet of Pisces, which is located at the Western end of Pisces, the Fishes. The Circlet comprises six stars of fourth and fifth magnitude, although under light-polluted skies it is likely that some or all of them will not be seen with the naked-eye. The passage began at 0930 UT on June 8th when the planet passed 10°.5 South of Aqr (Gamma Piscium, mag. +3.7), the Westernmost star of the Circlet.
At 0630 UT on June 9th Mars passed 2°.0 South of the star 96 Aqr (96 Aquarii, mag. +5.7), a double star with a magnitude +10.4 companion located 10" distant. Mars will occult this star in the evening sky in January 2032.
On June 12th Mars reached 10".0 in angular diameter, positioned about 91° West of the Sun. The planet was now brightening significantly with each passing week, its pale orange coloration seemingly more obvious than in the preceding months. For telescopic observers, the planet was now at a sufficiently large apparent size for significant surface detail to be seen and for a regular observing campaign to begin. At 1220 UT on the same day Mars (mag. -0.2) passed 1°.7 South of the planet Neptune (+7.9) in a planetary conjunction which was ideally placed for Southern hemisphere observers. Neptune was only a few months away from opposition and was only 0.1 magnitude below its peak brightness for the year. This was an ideal opportunity for those who had never seen our most distant Solar System planet to locate it with relative ease, using Mars as a bright locator-beacon.
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Mars completed its passage of the Circlet on June 20th when it passed 8°.0 South of the star TX Psc or 19 Psc (19 Piscium, mag. +5.1v), positioned at the Eastern end of the asterism. It is a red giant variable star with a small irregular brightness variation of between magnitudes +4.8 and +5.2. Having now passed the Circlet, Mars entered Pisces through its South-western border on June 24th, where the planet would spend its closest and brightest period of the 2019-21 apparition.
Mars passed 10º.1 South of the star Psc (Omega Piscium, mag. +4.2), located at the Southern fish's tail, on June 26th. The planet entered the constellation of Cetus, the Whale or Sea Monster, on July 8th, clipping the constellation's North-western border with Pisces.
On July 11th the planet crossed to the North of the celestial equator (declination = 0°), positioned 8º.5 East of the First Point of Aries, the point on the ecliptic where the Sun crosses the celestial equator each year at the Spring (Vernal) Equinox.
Mars Global Dust Storm At the height of the 2018 dust storm, a few weeks before the planet's opposition, Mars appeared pale orange or orange-yellow, its surface features being indistinct and of low contrast (click on the thumbnail for a larger version, 4 KB). This image of the storm at its peak was captured by Luis Amiama Gomez (Santo Domingo, Dominican Republic) using an 8-inch Newtonian telescope fitted with a CMOS camera (Image: Luis Amiama Gomez / ALPO-Japan).
On July 16th Mars passed 18º.9 North of the star Diphda ( Cet or Beta Ceti, mag. +2.0), at the South-western corner of Cetus. The name Diphda is Arabic for 'tail of the whale' and is the brightest star in the constellation. Before IAU standardisation in 2016 it was alternatively known by the names Deneb Kaitos, Difda al Thani and Rana Secunda.
The Red Planet passed 6º.2 South of the star Psc (Delta Piscium, mag. +4.4), positioned about half-way along the Southern half of the Pisces figure, on July 19th. The star is one of several which on old star maps mark the long and winding cord between the Northern and Southern Fishes. On July 26th Mars re-entered Pisces through its Southern border, having traversed a 9º.7 long track through a corner of Cetus. Also on the 26th, Mars passed 5º.1 South of the star Psc (Epsilon Piscium, mag. +4.2), another star in the meandering cord. Mars would pass this star - and several other moderately bright stars in this region - on more than one occasion before the year was out.
Positioned 2°.7 to the East of Psc is the double star Revati ( Psc or Zeta Piscium,, mag. +4.9), a Sanskrit name adopted by the IAU in 2017 and derived from an ancient Hindu lunar mansion. Mars passed 3°.9 South of Revati on August 2nd. The star comprises two components of magnitude +5.2 and +6.3, separated by a wide 23" (0'.4) and easily split in small telescopes.
Mars reached perihelion (its closest orbital position to the Sun) on August 3rd, positioned at a distance of 1.3814 AU (206.6 million kms or 128.4 million miles) from the Sun.
From around 08 hours UT on August 9th the waning gibbous Moon passed in front of Mars in the third lunar occultation of the apparition. Much like the lunar occultation of March 18th, the event was visible in darkness from the Southern tip of South America (Southern Argentina and Southern Chile), Drake Passage and part of Antarctica. It was, however, also visible from Uruguay, South-eastern Paraguay, South-eastern Brazil and the South-west Atlantic Ocean (including the Falkland Islands). For a map and timings of this event, follow the link provided in the Moon near Mars section below.
By mid-August Mars had returned to naked-eye view from higher Northern latitudes, moving from East through to SSE, although it was seen in continuous twilight.
Mars passed 1º.0 South of Psc (Mu Piscium, mag.+4.8) on August 13th and 10°.0 South of the star Alpherg ( Psc or Eta Piscium, mag. +3.8), the brightest star in Pisces, on August 14th. On August 23rd the planet passed 31' (0°.5) North of Psc (Nu Piscium, mag.+4.4). All three of these stars are located along the cord.
Mars' Eastward motion against the background stars had slowed considerably since the beginning of August, from 0º.45 per day at that time to just 0º.25 per day by the third week of that month.
On August 28th the planet passed 2º.7 South of the star Torcular ( Psc or Omicron Piscium, mag. +4.2), positioned about one-third of the way along the Northerly section of the cord. The star's long-form name is Torcularis Septentrionalis which is a mis-translation of the original Greek word '' meaning 'flax', i.e. the aforementioned cord that tied the two fishes' tails together.
On September 6th Mars was involved in the fourth lunar occultation of the apparition. From around 04 hours UT the waning gibbous Moon passed in front of the planet, an event visible in darkness from central South America, the central Atlantic Ocean, North-west Africa and Southern Portugal. Follow the link below for a map and timings of the event.
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Prior to 2020, Mars had last reached opposition in Capricornus in July 2018 (click on the thumbnail for the full-size photo, 131 KB). This photograph, taken by the writer, shows the Red Planet two days before opposition day. Mars (magnitude -2.7) was positioned at the South-west of the constellation, a short distance West of the star Cap (Phi Capricorni, mag. +4.1). The pale glow in the lower part of the photo was caused by the gibbous Moon, which was low in the sky to the right of picture. The photo was taken from latitude 51° North, facing South at around midnight local time. Click here (18 KB) to see an annotated version of the photograph.
On September 10th Mars' Eastward motion ceased as the planet reached its Eastern stationary point, positioned 2º.6 to the SSE of Torcular and 2º.4 North-east of Psc. Over the next few days its apparent motion changed direction from East-North-easterly to West-South-westerly as its motion became retrograde. The planet's WSW motion would continue for the next two months.
Having reversed its motion against the background stars, Mars began to pass several of the stars that it had passed over the previous six weeks, but in reverse order. Moving retrograde, the planet passed 2º.5 South of Torcular on September 21st, 52' (0°.86) North of Psc on September 26th and 9°.5 South of Alpherg on October 5th.
A fifth lunar occultation of Mars took place on October 3rd when the waning gibbous Moon blocked the planet from view. The Earthbound visibility of this event matched that of March 18th, i.e. the Southern tip of South America (Southern Argentina and Southern Chile), Drake Passage and part of Antarctica, but with the addition of the Southern Atlantic Ocean.
At 1419 UT on October 6th Mars reached its closest point to the Earth for this apparition, at 0.4149 AU distant (62.0 million kms or 38.5 million miles), a point known as the perigee (or, in the specific case of Mars, the periareion). The Red Planet now shone at magnitude -2.56 (its brightest for the apparition) and its apparent size was 22".5 (its largest for the apparition). This was double the size that it was in early July and triple the size it was in late April. Shortly after midnight (UT) on the following day (7th) Mars passed 22' (0º.36) South of Psc, this time moving retrograde.
Mars reached opposition to the Sun at 2320 UT on October 13th in South-eastern Pisces, positioned 2º.3 to the WSW of Psc and 2º.9 South-east of Revati. The planet was now directly opposite the Sun in the sky (solar elongation = 180°), its illuminated phase was 100% and shone at magnitude -2.56. Mars was now the fourth brightest object in the night sky (after the Moon, Venus and Jupiter), easily outshining all of the stars around it. However, due to the eccentricity of Mars' orbit, its apparent disk size was not quite as large as it had been at its closest passage seven days earlier. Lying at a distance of 0.4192 AU from the Earth, Mars was now about 646,000 kms (401,400 miles) more distant than it was at perigee. Consequently its apparent size was fractionally smaller, at 22".3. On opposition day Mars was slowly moving towards the WSW at a rate of about 0º.3 per day. Mars shone at magnitude -2.5 for an 18-day period from October 2nd through to October 20th.
At opposition, a superior planet rises around sunset, is visible throughout the night and sets around sunrise. Its highest point in the sky is reached when it crosses (transits) the observer's meridian at local midnight (due South at midnight in the Northern hemisphere; due North at midnight in the Southern hemisphere). At the 2020 opposition Mars had a declination of +5°.44, i.e. it is a little over 5° North of the celestial equator. As such, this opposition was equally favourable for Northern and Southern hemisphere observers, Mars transitting the meridian at a reasonably high altitude in both hemispheres (at latitude 5º 26' North the planet transited at the zenith, directly above the observer's head).
On opposition day, Mars was experiencing Winter in its Northern hemisphere and Summer in its Southern hemisphere. The planet's Southern Pole was tipped towards the Earth at an angle of about 20º, giving us a good view of its Southern Polar Cap (SPC). Mars was positioned at a heliocentric longitude of 20º ( = 20°) and the areocentric longitude of the Sun (Ls) was 295°. The Martian Year was 35, the Martian Month was 10 and opposition day equated to Sol Number 555 on Mars. The equivalent Earth date on Mars - called the Martian Date (MD) - was January 15th. All the terms given in this paragraph are explained in more detail on the Martian seasons page.
Mars at Closest Approach imaged by Avani Soares (Canoas, Brazil) on July 31st 2018, four days after opposition (click on the thumbnail for a larger image, 6 KB). This was the closest that the Red Planet had come to the Earth in almost 15 years. Soares used a 14-inch reflector telescope fitted with a CMOS camera (Image: Avani Soares / ALPO-Japan).
At the 2020 opposition, Mars was 0.22 magnitudes dimmer than at its previous opposition in July 2018, a brightness difference which was barely perceptible to the naked-eye. Its apparent disk diameter was about 7% smaller than at the 2018 opposition but nonetheless it was the largest apparent disk size that the planet would show to the Earth before the year 2035. Such relatively close oppositions to Earth are known as perihelic oppositions, since they take place when Mars is near the perihelion point of its orbit (for more details, see the Mars oppositions page).
Opposition day having passed, the solar elongation changed from Westerly to Easterly and the angle reduced below 180°. By October 22nd - nine days after opposition - Mars' solar elongation had reduced to 170° East of the Sun.
Mars continued its retrograde motion through South-eastern Pisces. On October 19th the planet passed Revati again, on this occasion passing 2°.5 South of the star, i.e. 1°.4 closer than its previous passage of this star in early August. The planet then passed 3º.1 South of Psc on October 30th, a full 2° closer than its previous passage in late July.
On November 16th Mars' retrograde motion ceased when it reached its Western stationary point, at which time the planet appeared to form a near-equilateral triangle with the stars Psc (3º.1 to the North-east) and Psc (3º.0 to the North-west). Mars moved slowly Northwards against the background stars for a few days before turning direct once more and heading back towards the ENE.
Mars crossed to the North of the ecliptic on December 2nd. The planet's ecliptic crossing at this point - only 50 days after opposition - was significant because it affected the shape of the path described by the planet against the background stars during this period. If a superior planet crosses the ecliptic close to the time of its opposition to the Sun, its apparent path will not be a loop (as in the majority of planetary oppositions) but a zig-zag (i.e. 'Z' or 'S'-shaped'). The zig-zag is Northward-facing ('Z') when the planet crosses the ecliptic Northwards and Southward-facing ('') when crossing it Southwards (for more information on the loops and zig-zags described by the planets in the night sky, see the Planet Movements page).
Now moving direct, Mars began to pass a number of stars which it had already passed on two occasions before. The planet passed 1º.1 South of Psc on December 2nd, a full 4° closer than its first passage of this star four months earlier. At 1820 UT on December 13th Mars passed just 41' (0º.68) North of Revati, its previous two passages (in early August and mid-October) having been a few degrees to the South of it. Mars passed 4º.1 North of Psc on December 26th, almost 4º.5 further North than at its previous passage in early October.
By the third week of December Mars had faded back to minus zeroth magnitude (-0.5) and its apparent diameter had reduced to 11".5 - only half that at its closest approach back in early October. Meanwhile on December 21st, some 83º away to the South-west in Capricornus, Jupiter and Saturn reached conjunction for the first time in 20 years - an event known historically as a Great Conjunction (for more details see the Jupiter 2019-22 page).
Mars passed 4°.9 South of Alpherg once more on December 27th, some 5°.1 closer to the star than it was in August and 4°.6 closer than it was when moving retrograde in early October. Alpherg is Arabic for 'the cord' and the name appears infrequently on star charts. It is a yellow giant star which, to most amateur astronomers, serves as a convenient 'finder star' for the galaxy M74 (NGC 628) which is positioned 1°.3 to the ENE of the star. M74 is a 10th-magnitude face-on spiral, being one of the faintest objects in the Messier catalogue.
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In the weeks leading up to its Eastern stationary point in mid-September 2020, Mars was positioned around 4°.0 South of the ecliptic, but by the start of 2021 the planet was positioned 0°.9 North of the ecliptic - a shift of almost 5° Northwards from its pre-retrograde position. Having retrograded to the WSW from mid-September to mid-November, then having ceased motion at its Western stationary point and crept slightly Northwards, its apparent direction of travel against the background stars was now almost parallel to the path that it had taken in the weeks leading up to its Eastern stationary point; namely, to the ENE. As Mars headed towards the Piscean border with Aries, the Ram, it passed two more reasonably bright stars in Pisces which it had already passed on two occasions in previous months. Moving direct, Mars passed 6°.0 North of Psc on January 2nd, 5°.5 further North than its initial passage of this star in late August 2020 and 5°.1 further North than its retrograde passage in late September 2020. Finally, the planet passed 2º.7 North of Torcular on January 4th - 5°.2 further North than its retrograde passage of this star in mid-September, at which time it had passed to the South of the star.
Mars entered Aries on January 5th, its apparent diameter falling below 10".0. The planet passed 6º.5 South of the double star Mesarthim ( Ari or Gamma Arietis, mag. +3.9) on January 9th. Easily resolved in small telescopes, it comprises two white stars of magnitudes +4.6 and +4.7, separated by 7".5. On January 10th the planet passed 7º.9 South of the star Sheratan ( Ari or Beta Arietis, mag. +2.6). The name Mesarthim is Arabic in origin but its meaning is unclear, however the star has been associated with Sheratan (Arabic for 'the signs') since ancient times, when the stellar pair were considered to mark the New Year.
At 23 hours UT on January 11th Mars was positioned at precisely 1.0000 AU from the Earth, i.e. the same distance as the average distance of the Earth from the Sun (149.5 million kms or 92.9 million statute miles). When the planet was last 1.0000 AU from Earth in June 2020 its distance from Earth was slowly reducing; now the planet's distance was slowly increasing. As was the situation six months earlier, when viewed from a point in space far above the Earth's North pole, the Earth, Mars and the Sun would again have appeared to form an isosceles triangle, with Earth positioned at the apex.
In mid-January Mars' apparent magnitude returned to positive (+0.0). On January 14th Mars passed 10°.9 North of the double star Alrescha ( Psc or Alpha Piscium, mag. +3.8), in neighbouring Pisces. The name was standardized by the IAU in 2016, the star having been previously known as Al Rischa, Alrisha or Al Rescha. It comprises two blue-white components of magnitudes +4.1 and +5.1, separated by an angular distance of 1".8 on a roughly East-West orientation. Telescopes of at least 75 mm (3 in) aperture are required to split the pair. The planet passed 9°.2 South of the Aries' brightest star Hamal ( Ari or Alpha Arietis, mag. +2.0) on January 17th. In 2011 the star was found to have an extra-solar planet or exoplanet (a planet outside our own Solar System) orbiting around it. Mars passed almost mid-way between Alrescha and Hamal on January 15th.
At around 1040 UT on January 21st, zeroth magnitude Mars passed 1º.7 North of the sixth magnitude planet Uranus in the fourth planetary conjunction of the 2019-21 apparition. The conjunction was visible worldwide and was the only one of the apparition which favoured Northern hemisphere observers. Uranus, now in the final stages of its 2020-21 apparition, fully entered Aries in early 2019. For more details on the visibility of this and the other planetary conjunctions involving Mars during the 2019-21 period, refer to the planetary conjunctions section below.
Mars at Minimum Phase by two Japanese amateur astronomers some 540 kms (335 miles) apart on November 15th 2018, showing the details recorded by naked-eye and by CMOS image (click on the thumbnail for larger image, 16 KB). In both cases the Red Planet was around 40° high towards the South at dusk. Ito's digital image was taken around 30 minutes after Nakano's sketch was completed, the planet having rotated about 9° in that time (Images: Yuukichi Nakano / Satoshi Ito / ALPO-Japan).
On January 23rd Mars attained its minimal illuminated phase for the Eastern elongation period of the apparition, at 88.5%. Note that this was not the minimum illuminated phase for the apparition - this took place in June 2020, when the phase was 4% smaller. The planet now shone at magnitude +0.3, its apparent diameter being 8".4 and its solar elongation 94º East. Unlike at Western quadrature, the illuminated part of the planet's disk faced Westwards (not Eastwards, as before) because it was now positioned to the East of the Sun when seen from the Earth. Nine days later, on February 1st, Mars reached Eastern quadrature, when it was positioned 90° East of the Sun and showed a fractionally larger phase of 88.6%. If the orbit of Mars was perfectly circular, the quadrature and minimum phase dates would always coincide, however since the planet's orbit is eccentric, they do not.
Mars was now setting 9¾ hours after the Sun at latitude 60° North, 7½ hours after the Sun at 40° North, 5½ hours after sunset at the Equator and four hours after sunset at 35° South. The planet set in the North-west from higher Northern latitudes but in the WNW from elsewhere. For observers located South of latitude 27º North, Mars had already crossed the local meridian before it came into view in the dusk twilight. For observers located North of 27º North, the planet had not yet reached the meridian when it came into view.
On February 6th Mars passed 9º.4 South of the variable and double star Bharani (41 Ari or 41 Arietis, mag. +3.6), named after the second lunar mansion in Hindu astrology. It is another name which was adopted by the IAU in 2017. On February 10th the planet passed 2º.9 South of Ari (Epsilon Arietis, mag. +4.6), which is also both a double star and a variable star. Its two white components are magnitudes +5.2 and +5.5 and are separated by just 1".5, requiring telescopes of at least 100 mm (4 in) and high magnification in order to split them. At 1030 UT on February 16th the planet passed 27' (0º.45) South of the star Botein ( Ari or Delta Arietis, mag. +4.3) which on older star maps marked the hind leg of the Ram.
Mars entered Taurus, the Bull, on February 24th. Between March 2nd and 4th the planet passed around 2°.5 South of the constellation's most famous asterism known as the Pleiades or Seven Sisters (M45). The planet took about 43 hours to traverse the 1° angular distance between the cluster's brightest Western star (Electra, mag. +3.7) and its brightest Eastern star (Atlas, mag. +3.6).
On March 9th Mars passed 9°.6 North of the eclipsing binary star Tau (Lambda Tauri), positioned at the upper 'chest' of the Bull figure, whose magnitude varies from ca. +3.5 to +4.0 over a period of four days. The following day (10th) the planet passed just 12' (0°.2) North of the star 37 Tau (37 Tauri, mag. +4.3), which is positioned 4°.6 to the South-east of the Pleiades.
At 1520 UT on March 14th the distance between the Earth and Mars was the same as that between the Sun and Mars, at 1.5980 AU (239.0 million kms or 148.5 million miles). The configuration resembled that which took place in March 2020, although the Earth-Mars distance was slightly greater on this occasion. Seen from far above the Earth's North pole, the Earth, Mars and the Sun again appeared to form an isoscelene triangle in space, with Mars positioned at the apex.
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Between March 16th and 23rd Mars passed several degrees to the North of a large star cluster called the Hyades, a distinct 'V'-shaped grouping of stars which form the head of the Bull. The cluster comprises around 400 stars spread over an exceptionally large area of about 5° of the sky. On March 16th Mars passed 7°.3 North of the star Prima Hyadum ( Tau or Gamma Tauri, mag. +3.6), positioned at the apex of the 'V'. Before the name was standardized by the IAU in 2017, the star was known variously as Primus Hyadum or Hyadum I. On March 17th Mars passed 5°.6 North of Secunda Hyadum (1 Tau or Delta-1 Tauri, mag. +3.7), a triple star system positioned about half-way along the Northern arm of the cluster. Before IAU standardization the star was also known as Secundus Hyadum or Hyadum II.
Positioned a few degrees North of the Hyades is a grouping of stars of between 4th and 6th magnitude which straddle the ecliptic. At the North-eastern corner of the group are the stars Tau (Upsilon Tauri, mag. +4.3) and 72 Tauri (mag. +5.5). Mars passed 22' (0°.36) North of Tau at around 0550 UT on March 19th, then at around 1505 UT that same day, 13' (0°.21) North of 72 Tau. Mars will occult this star in the evening sky in March 2036.
Also positioned along the Northern arm is the star Ain ( Tau or Epsilon Tauri, mag. +3.5), which on older star maps marked one of the Bull's eyes. Mars passed 4°.2 North of the star on March 20th. At the same moment the planet passed 7°.5 North of Chamukuy (2 Tau or Theta-2 Tauri, mag. +3.7), positioned about half-way along the Southern arm of the cluster. The name is that of a small bird in Yucatec Mayan culture and it was adopted by the IAU in 2017. The star forms a naked-eye yellow-white double with 1 Tau (Theta-1 Tauri, mag. +3.8), positioned some 5'.6 (0°.09) to the North.
On March 23rd Mars passed 7°.1 North of Aldebaran ( Tauri, mag. +0.9), the brightest star in Taurus, positioned at the South-eastern corner of the 'V' and marking the other 'eye' of the Bull. Aldebaran appears orange-red to the naked-eye since it is a red giant star. It appears to be part of the cluster but in fact, it is not a physical member of the Hyades group; its appearance in the cluster is purely a line-of-sight effect. The Hyades lie at a distance of about 150 light years from Earth whereas Aldebaran is much closer, at 68 light years. Now having faded to magnitude +1.2, pale orange Mars was only slightly dimmer than Aldebaran at this time, which helped to allow a comparison of the contrasting colours between star and planet.
On March 25th Mars passed 48' (0°.8) North of Tau (Tau Tauri, mag. +4.2), another star which, like Aldebaran, is not part of the Hyades group. Positioned at the base of the Bull's Northern horn, it is a multiple-star system and a member of an obscure open cluster known as Alessi 51.
From March 26th to May 3rd Mars passed to the North of Orion, the Hunter, perhaps the most recognisable constellation in the night sky. Orion had already been visible for several months and was now in the final stages of its seasonal appearance, setting in the West an hour or so before local midnight. Mars left the star chart coverage (above) on April 5th, passing 18°.6 North of Bellatrix ( Ori or Gamma Orionis, mag. +1.6), the North-western corner star of Orion's distinctive quadrilateral, on April 10th.
On April 11th Mars passed 3°.9 South of the star Elnath ( Tau or Beta Tauri, mag. +1.6), which is located at the tip of the Bull's Northern horn. The name was standardized by the IAU in 2016, previous versions of the name being spelled Al Nath, El Nath or simply Nath. The star also neatly completes the six-sided figure comprising the stars of Auriga, the Charioteer, located to the North-east of Taurus. Mars' apparent diameter fell below 5" on April 13th.
Table showing the position and apparent magnitude of Mars for the latter part of the 2019-21 apparition (click on thumbnail for full-size table, 17 KB). As in the first table, the magnitudes, diameters and solar elongations refer to the middle of the period in question.
The star marking the tip of the Bull's Southern horn is Tianguan ( Tau or Zeta Tauri, mag. +2.9v), another 'new' name adopted by the IAU in 2017. The name derives from Chinese astronomy, in which the star is known as the Celestial Gate, part of an asterism contained within a mansion called Bì Xiù ('the Net'). Mars passed 3°.7 North of Tianguan on April 15th.
The sixth and final lunar occultation of the planet's apparition took place on April 17th, when the waxing crescent Moon passed in front of Mars from around 13 hours UT. The event was visible in darkness from South-east Asia. For a map and timings of the event, follow the link provided in the Moon near Mars section below.
On April 22nd Mars attained its most Northerly declination for this apparition ( = +24° 53' 55" or +24°.8985), the most Northerly declination attained by the planet since January 2008 and before December 2022. Mars now set at its most Northerly point along the local horizon, the actual point of setting depending upon the observer's latitude. This would be towards the North-west at higher Northern latitudes and towards the WNW at most other inhabited latitudes. On the same day Mars passed 17°.6 North of Betelgeuse ( Ori or Alpha Orionis, mag. +0.7v), the orange-red variable star at the North-eastern corner of Orion's quadrilateral. With Mars now having faded to magnitude +1.5, Betelgeuse - even with its fluctuating brightness between magnitudes +0.0 and +1.3 - shone brighter than the Red Planet at this time. Mars passed to the North of Orion's 'club', topped by the stars 1 Ori and 2 Ori (Chi-1 and Chi-2 Orionis, mags. +4.4 and +4.6), from April 22nd to 28th.
Mars entered Gemini, the Twins, on April 24th, passing 1°.6 North of the star 1 Gem (1 Geminorum, mag. +4.2), at the Western end of the constellation, on April 25th. A short distance North-east of 1 Geminorum is the open star cluster M35 (NGC 2168). The cluster has an apparent diameter of 30' (about the apparent size of the Full Moon) and contains over 400 stars(!) It can be glimpsed with the naked-eye as a misty patch of light on a dark, clear night. Mars passed about 33' (0°.55) North of the cluster's centre between 01 hours and 19 hours UT on April 27th. The planet passed 2°.3 North of Propus ( Gem or Eta Geminorum, mag. +3.5v), also referred to as Tejat Prior before IAU standardization, on April 29th.
By late April Mars' solar elongation had reduced to 54° and twilight began to interfere with observation of the planet as seen from latitudes North of about 60° North. At these latitudes the planet was visible for around six hours before setting in the NNW, the planet being in twilight throughout. Elsewhere the planet was setting in darkness, towards the North-west (at mid-Northern and mid-Southern latitudes) and to the WNW (from the Northern Tropics to mid-Southern latitudes). At latitude 40° North, Mars set about 4¾ hours after sunset and at the Equator it set around four hours after sunset. At mid-Southern latitudes the planet set 3¼ hours after the Sun. The altitudes of the planet, as it became visible in the dusk twilight, were: 33° at 60° North, 46° at 40° North, 47° at the Equator and 25° at 35° South.
On May 2nd Mars passed 2°.2 North of the star Tejat ( Gem or Mu Geminorum, mag. +3.0v), which together with Propus marks the Northern twin's lower left leg. Before IAU standardization the star was known by the name of Tejat Posterior, among others. On May 8th the planet passed 8°.3 North of Alhena ( Gem or Gamma Geminorum, mag. +1.9), at the ankle of the Southern Twin's left leg.
In early May Mercury (mag. -0.9), then in Western Taurus, emerged into the dusk sky for its second evening apparition of 2021. This particular evening apparition favoured Northern hemisphere observers, the ecliptic forming a steep angle to the Western horizon at dusk at this time of year. Brilliant Venus (mag. -3.8), positioned on the Aries-Taurus border, also emerged at dusk around the same time, at the start of its 2021-22 evening apparition. In early May Mercury was positioned 38° to the West of Mars whilst Venus was several degrees to the South-west of Mercury. Venus approached Mars from the West, gaining on the Red Planet by about 0°.7 per day. Mars and Venus would reach conjunction in mid-July.
At 0930 UT on May 10th Mars passed 38' (0°.63) South of Mebsuta ( Gem or Epsilon Geminorum, mag. +3.0), a yellow supergiant double star positioned at the 'groin' of the Northern Twin.
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'Conjunction of Mars and Antares' An oil painting by Chinese artist Luo Fangyang (Taicang City, Jiangsu, China) (click on the thumbnail for a larger version, 44 KB). The painting depicts the passage of Mars near Antares, the brightest star in Scorpius, along with a couple of other constellations, in a classically Chinese landscape setting. Fangyang cites astronomy as his main source of artistic inspiration. Click here to see the artist's original internet posting and see more of his work at the CloudyNights forum.
At around 0240 UT on May 17th Mars (mag. +1.7) formed an isosceles triangle with Gemini's two luminaries Castor ( Gem or Alpha Geminorum, mag. +1.6) and Pollux ( Gem or Beta Geminorum, mag. +1.1), Mars being positioned at the apex. The long sides of the triangle measured 10°.6 and the angular distance of the short side (from Castor to Pollux) was 4°.5. Both stars were slightly brighter than Mars at this time. The temporary celestial triangle pointed South-westwards towards Orion's club. The triangle was visible after dusk from central America, the Eastern half of North America and the South-east Pacific Ocean. The waxing crescent Moon was positioned a few degrees South of Pollux. Later that same day Mars passed 3°.5 North of the variable and optical double star Mekbuda (Gem or Zeta Geminorum, mag. +3.9v), positioned at the upper left leg of the Southern Twin (Pollux).
Mercury, having faded slightly to magnitude +1.0, reached greatest elongation (22° East of the Sun) on May 17th, positioned 26° to the West of Mars. The two planets came to within 25°.2 of each other on May 21st, at which time Venus was positioned 7° to the WSW of Mercury. Mars passed 1°.6 North of the double star Wasat ( Gem or Delta Geminorum, mag. +3.5) on May 23rd.
Venus and Mercury were involved in a close conjunction on May 29th, separated by just 24' (0°.4), positioned 27° to the West of Mars. Mercury headed out of view in the dusk twilight in early June.
Mars passed 8°.7 South of Castor, which is Gemini's second-brightest star, on May 29th. On May 31st the planet passed 11°.6 South of another star whose 'new' name was officially recognised by the IAU in 2017. Jishui ( Gem or Omicron Geminorum, mag. +4.9) is positioned close to the constellation's Northern border with Lynx. The name comes from ancient Chinese astronomy, Jishui being the water flow from the River Beihe which was used for wine-making and brewing. In the Chinese night sky the river was identified with the stars Castor, Pollux and nearby Gem (Rho Geminorum, mag. +4.2).
On June 2nd at 0240 UT Mars, the star Gem (Kappa Geminorum, mag. +3.5) and Gemini's brightest star Pollux lined up along 5°.3, aligned roughly celestial North and South. When the line was extended 17°.6 to the South it led to the bright star Procyon ( CMi or Alpha Canis Minoris, mag. +0.5) in the constellation of Canis Minor, the Lesser Dog. Mars passed 1°.7 South of Gem itself 3½ hours later, then 5°.4 South of Pollux some 12 hours after the line-up.
Mars entered Cancer, the Crab, at around 08 hours UT on June 8th. As it did so, Castor, Pollux and Mars formed a line 11°.4 long, orientated NNW-SSE, pointing Southwards towards the head of Hydra, the Water Snake, which was positioned 19° to the SSE of Mars. The line-up was visible after dusk from Eastern Australia, Papua New Guinea and Micronesia.
Mars passed just 1'.8 (0°.03) South of the star 2 Cnc (Mu-2 Cancri, mag. +5.3), in Eastern Cancer, at 0448 UT on June 11th. The star 1 Cnc (Mu-1 Cancri, mag. +6.0) is located 1°.1 to the NNW.
On June 14th Mars passed 12°.0 North of Cancer's brightest star Tarf ( Cnc or Beta Cancri, mag. +3.5), at the South-western corner of the constellation's lambda-shaped () figure. Prior to IAU standardisation in 2018 it was known by the name Altarf, which is Arabic for 'the End', i.e. the end of the Crab's leg.
Since early May Venus had been a constant presence in the dusk sky, positioned over 25° to the West of Mars and slowly pulling away from the Sun day by day. During the first half of June Venus had been approaching the Red Planet at a rate of 0°.6 per day and by June 15th the planet was in central Gemini, some 17° to the West of Mars. At midnight UT on June 17th Venus was 15°.8 West of Mars; on the 19th it was 14°.5 to the WNW of the Red Planet, on the 21st it was 13°.3 to the WNW of it and on the 23rd it was 12°.2 to the WNW of it.
Warrrior in the Cradle Astronomical artist Jeremy Perez produced this graphite representation of Mars passing through M44 (The Beehive Cluster) in September 2013, based on an observation using 12x80 binoculars (click on the thumbnail for a larger image, 7 KB). '[Mars] was bright orange', he says, 'between blue and white stars'. See the full-size illustration at the ASOD website (Image: Jeremy Perez / ASOD).
On June 23rd Mars passed through the star cluster Praesepe, also known as the Beehive Cluster (M44 or NGC 2632). Under dark, rural skies it is visible to the naked-eye as a hazy patch of light and in city locations it is easily seen in binoculars. 'Praesepe' is a Latin word meaning 'manger', so named after the Nativity story in the Christian Bible; indeed, another less commonly used name for the cluster is the Manger. Mars took three hours to traverse the angular width of the cluster, passing through the centre of it from 08 hours UT to 11 hours UT on the 23rd.
Also present in the Nativity story were two donkeys, and they are represented in the night sky by two fourth-magnitude stars. Asellus Borealis ( Cnc or Gamma Cancri, mag. +4.6), the Northern donkey, and Asellus Australis ( Cnc or Delta Cancri, mag. +3.9), the Southern donkey, are separated by 3º.3 and they flank the Praesepe cluster in central Cancer. Mars passed 2°.0 South of Asellus Borealis at around 02 hours UT on June 25th and 1°.2 North of Asellus Australis at around 1520 UT on the same day. The planet passed between the two stars at about 10 hours UT.
Venus, now in Cancer, continued its approach to Mars, being 9°.7 WNW of the Red Planet at midnight UT on June 27th, 8°.5 WNW of it on the 29th and 7°.4 WNW of it on July 1st. On the same day Mars passed 6º.6 North of Acubens ( Cnc or Alpha Cancri, mag. +4.3), a double star positioned towards the South-eastern corner of the constellation. Venus was 6°.2 WNW of Mars on July 3rd, 4°.4 WNW of it on the 6th and 2°.7 WNW of it on the 9th.
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In early July, observers at high Northern latitudes were the first to bid farewell to the Red Planet as it slipped into the dusk twilight. Over the next month the 'observing window' for Mars also reduced considerably for observers at mid-Northern latitudes.
Mars entered Leo, the Lion, on July 10th, with Venus trailing behind it, 1°.8 away to the North-west. By midnight UT on July 12th Venus was only 1°.0 to the North-west. At 07 hours UT on July 13th Venus passed 0°.5 to the North of Mars, moving at twice the apparent speed of the Red Planet, in the fifth planetary conjunction of the 2019-21 apparition. The planetary pair were positioned a short distance South-west of the Sickle of Leo asterism (forming the head and chest of the Lion) and only 1°.6 from Leo's border with Cancer. On the same day, Mars reached aphelion (its most distant orbital position from the Sun) at a solar distance of 1.6659 AU (249.2 million kms or 154.8 million miles). Following conjunction, Venus raced on ahead of Mars, being 0°.9 ENE of the Red Planet at midnight UT on July 15th, 1°.5 East of it on the 16th, 2°.0 East of it on the 17th and 2°.6 ESE of it on the 18th.
Also on July 18th, Mars passed 5°.2 North of the star Subra ( Leo or Omicron Leonis, mag. +3.5), a name which is Arabic for a mane or shoulder. At this time of year observers at higher Northern latitudes are unable to see the star, due to its low altitude and the long Summer twilight. From July 21st through to August 4th the planet passed to the South of the aforementioned Sickle of Leo, at the Western end of the constellation; to the naked-eye it appears as a backward question-mark (). The passsage of the Sickle began as Mars passed 9°.0 South of the star Ras Elased Australis, also known as Algenubi ( Leo or Epsilon Leonis, mag. +2.9), at the upper North-western end ('pointed end') of the sickle, on July 20th.
On July 21st Venus, now 4°.8 ESE of Mars, passed North of Leo's brightest star Regulus ( Leo or Alpha Leonis, mag. +1.4), at the base of the sickle. Mars itself passed 41' (0°.7) North of Regulus on July 29th, by which time Venus was in central Southern Leo, having extended its lead on the Red Planet to 9°.3.
The Eastern end of the Sickle is marked by the star Algieba (1 Leo or Gamma-1 Leonis, mag. +2.3), which is at the base of the Lion's neck (although the name is Arabic for 'the forehead'). It is a double star with golden-yellow components (1 Leo and 2 Leo) of magnitudes +2.3 and +3.6, separated by an angular distance of 4".7. Mars passed 8°.3 South of the star - thus completing its passage of the Sickle - on August 3rd. Venus was now 12° to the ESE of Mars and pulling further away from it.
Mars' solar elongation fell below 20° on August 8th. The planet was now setting 1 hour after the Sun from 40º North latitude and around 1½ hours after the Sun from latitudes South of the Equator. Mars now set in the WNW in the Northern hemisphere and in the West in the Southern hemisphere. At latitude 40° North Mars stood just 7° above the horizon when it first became visible at dusk; at the Equator the planet stood 16° high as it came into view whilst at 35° South it was 15° above the horizon. By mid-August Mars had become lost from view from mid-Northern latitudes.
In mid-August Mercury (mag. -0.6) entered the dusk sky in its third evening apparition of 2021, this particular one favouring Southern hemisphere observers. The planet moved rapidly from the WNW, gaining on Mars by 0°.9 per day - twice the apparent daily motion of the Red Planet. At midnight UT Mercury was positioned 4°.6 to the WNW of Mars on August 15th, 3°.4 WNW of it on the 16th, 2°.3 WNW of it on the 17th and 1°.2 WNW of it on the 18th. At 04 hours UT Mercury (now mag. -0.4) passed just 5' (0°.08) to the South of Mars (+1.8) in the final planetary conjunction of the 2019-21 apparition. The pair were positioned to the South of the Lion's belly, with Venus (mag. -3.9) over 20° away to the ESE in the constellation of Virgo, the Virgin. With its return to central Leo, Mars had now completed a full circuit of the zodiac since passing through superior conjunction nearly two years earlier.
By midnight UT on August 20th Mercury was 0°.9 to the ESE of Mars. It was 1°.9 ESE of the Red Planet on the August 21st, 2°.9 ESE of it on the 22nd and 3°.9 ESE of it on the 23rd, by which time Mars' solar elongation had reduced to 15° East of the Sun. Mercury, having faded slightly to magnitude -0.1, entered Virgo on August 26th, positioned 6°.8 to the South-east of Mars.
By late August the stars of Leo are heading into the dusk twilight, the constellation's brighter stars only being visible from Equatorial and Northern Tropical latitudes. Mars passed 9°.4 South of the star Chertan ( Leo or Theta Leonis, mag. +3.3), at the top of the Lion's rear leg, on August 26th. Prior to IAU standardisation in 2016 the star was also known as Coxa or Chort. At the same moment the planet passed 14°.5 South of the star Zosma ( Leo or Delta Leonis, mag. +2.7), at the rump of the Lion. Being slightly brighter than Chertan, Zosma is visible in twilight as far North as latitude 40° North at this time.
Mars entered Virgo on September 5th. At 11 hours UT on September 6th Venus (mag. -3.9), Mercury (+0.1) and Mars (+1.8) were equally spaced across the constellation from North-west to South-east, the angular distance between Venus-Mercury and Mercury-Mars being 15°.3. Venus was a short distance North-east of Virgo's brightest star, Spica ( Vir or Alpha Virginis, mag. +1.0) and Mercury a few degrees SSW of the star Porrima ( Vir or Gamma Virginis, mag. +2.9). The trio were best seen at dusk from far Western Australia and from central and Southern Indonesia.
Mercury reached its greatest elongation (26° East of the Sun) on September 14th, some 19° to the South-east of Mars. From Southern latitudes Mercury continued to be visible after dusk through to early October. Meanwhile Venus would reach its greatest elongation East of the Sun (47°) on October 29th.
Mars' solar elongation fell below 10º in early September, crossing to the South of the celestial equator on September 18th. The planet became lost from view from the Southern hemisphere by the third week of September, bringing the 2019-21 apparition to a close.
Mars reached its most distant point from Earth (known as the apogee or, in the case of Mars, the apoareion) for this apparition on September 20th, when it lay at a distance of 2.6381 AU (394.6 million kms or 245.2 million miles). Were it to have been visible from Earth at this time, its magnitude would have been +1.7 and its apparent size only 3".5. Mars reached superior conjunction (passing behind the Sun as viewed from the Earth) in central Virgo on October 8th, when it was 2.6286 AU (393.2 million kms or 244.3 million miles) from Earth.
The planet remained out of view - lost in the solar glare - for a further three weeks as it continued its Eastward course on the far side of its orbit from the Earth. Mars became visible again in the Eastern sky at dawn from late October 2021, when it was first glimpsed from Northern Tropical latitudes. This heralded the start of the 2021-23 apparition, which will see Mars reach opposition in Taurus in December 2022.
[Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]
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Mars Conjunctions with other Planets,
2020 to 2021
In the 2019-21 period there were six visible planetary conjunctions of Mars, involving each of the Solar System planets, three of which were in the morning sky and three in the evening sky. Two of them were either close or very close conjunctions. In all except one case their visibility favoured Southern hemisphere observers, due in large measure to the mostly Southerly declinations of the planets at the relevant times.
Perhaps the most interesting Martian conjunctions of the apparition were those with Jupiter and Saturn in the morning sky, not because of their visual appearance but because they took place only 11 days apart. As such, the viewing circumstances were almost the same in both events. With both planets being positioned far to the South of the celestial equator, they favoured Southern hemisphere observers and were unobservable North of about latitude 58° North.
The Mars-Jupiter conjunction of March 20th 2020 took place in North-eastern Sagittarius, the Red Planet passing 0°.7 to the South of the much brighter gas giant. At latitude 50° North the two planets were placed just 13° above the SSE horizon as the fainter planet (Mars) disappeared from view in the dawn twilight. At 30° North they were 31° above the SSE horizon at disappearance and at the Equator they were 55° above the South-eastern horizon. Altitudes in the Southern hemisphere were much better: 64° high in the East at latitude 25° South, 62° high in the ENE at 35° South and 57° high in the North-east at 45° South.
The Mars-Saturn conjunction of March 31st 2020 took place just across the border in Capricornus, when the Red Planet passed 0º.9 to the South of the ringed planet. The brightnesses of Mars and Saturn differed on this occasion by just 0.2 magnitudes. Jupiter and Saturn being so close together in the sky at this time, the altitudes and directions of this conjunction echoed those of the previous conjunction, although the slightly larger solar elongation in this instance put the altitudes slightly higher. At latitude 50° North Mars and Saturn were placed 13° above the SSE horizon as the planets disappeared from view in the dawn twilight. At 30° North they were 32° above the SSE horizon at disappearance and at the Equator they were 57° above the South-eastern horizon. The altitudes in the Southern hemisphere were again much better: 67° high in the East at latitude 25° South, 65° high in the ENE at 35° South and 59° high in the North-east at 45° South.
In the days between the Jupiter and Saturn conjunctions the three planets formed a close grouping on the Sagittarius-Capricornus border, Mars creeping slowly towards Saturn at a rate of about 0º.7 per day. The two gas giants were positioned only 6° or 7° apart during this period. It was the closest grouping between these three planets since April 2000 and before August 2040. Jupiter and Saturn themselves reached conjunction - an event known as a Great Conjunction - during the period of the Martian apparition, on December 21st 2020.
An evening conjunction between Mars and Venus on July 13th 2021 was a reasonably good one for Southern hemisphere observers, Venus passing about one apparent Full Moon distance (0°.5) to the North of the Red Planet. Taking place in the closing months of the Martian apparition, the event was not visible from higher Northern latitudes. Venus, at magnitude -3.8, was unmistakable but Mars, at magnitude +1.8, was about as faint as it can get when seen from the Earth. Venus could easily be seen in the dusk twilight but by the time Mars became visible the altitude of the pair had lowered considerably. From latitude 40° North the pair were positioned just 9° above the WNW horizon as Mars came into view, whilst at latitude 30° North they were 14° high in the West as the Red Planet appeared. From the Southern hemisphere the altitudes and directions under the same circumstances were as follows: 20° high in the WNW at 25° South; 18° high in the North-west at 35° South and 15° high in the North-west at 45° South.
Both conjunctions of Mars with the outer planets Uranus and Neptune took place at wide solar elongations (95° and 92° respectively), both events having the same planetary separations (1°.7). The evening conjunction between Mars and Uranus of January 21st 2021 took place in Aries and was visible worldwide; it also had the widest solar elongation of the six conjunctions. It was the only conjunction of the 2019-21 apparition which favoured Northern hemisphere observers. As Uranus came into view in the dusk twilight the two planets were positioned 42° in altitude towards the SSE at latitude 60° North, 64° in the South at latitude 40° North, 83° in the SSW at 20° North and 73° in the NNW at the Equator. In the Southern hemisphere the altitudes and directions were as follows: 46° high in the NNW at 25° South, 35° high in the NNW at 35° South and 22° high in the North-west at 45° South. At the moment of conjunction Uranus was 18 times further away than Mars and through telescopes it appeared less than half the apparent disk size of the Red Planet.
The morning conjunction between Mars and Neptune on June 12th 2020 was ideally placed for Southern hemisphere observers, the two planets being positioned in North-eastern Aquarius. At magnitude +7.9, Neptune was only 0.1 magnitude below its peak brightness for the year. Mars, at magnitude -0.2, shone brighter than at any of the other five planetary conjunctions of the period. By the time Neptune disappeared from view in the dawn twilight, the pair were placed 19° high in the South-east at 50° North, 45° high in the South-east at 30° North and 78° high in the ESE at at the Equator. In the Southern hemisphere they stood 79° high in the NNE when Neptune disappeared from view at 15° South, 60° high in the North at 35° South and 49° high in the NNW at 45° South. Telescopically Mars appeared 4½ times larger than Neptune and shone over 1700 times brighter! However any glare caused by the Red Planet's brightness was alleviated by the aforementioned wide separation between the pair.
The closest conjunction of the apparition was that between Mars and Mercury near the end of the apparition on August 19th 2021, when Mercury passed just 5' (0°.08) to the South of Mars. It was not observable from higher Northern latitudes, where Mars had already been lost from view. The event took place in the evening sky when the two planets were only 16° from the Sun and it was, therefore, a challenging one to observe from latitudes North of the Equator. Even from Southern latitudes the altitude of the pair was no higher than about 14° above the Western horizon as the fainter planet (Mars) came into view at dusk. The event was only seen against a darkened sky from latitudes South of about 10° South.
The following table lists the conjunctions involving Mars during the 2019-21 apparition which took place at solar elongations of 15º or greater. Where other planets were also in the vicinity, details are given. Note that, because some of the conjunctions occurred in twilight, the planets involved may not have appeared as bright as their listed magnitude suggests.
Mars conjunctions with other planets from March 2020 to August 2021 (click on thumbnail for full-size table, 34 KB). The column headed 'UT' is the Universal Time (equivalent to GMT) of the conjunction (in hrs : mins). The separation (column 'Sep') is the angular distance between the two planets, measured relative to Mars, e.g. on 2020 Mar 31, Saturn was positioned 0°.9 North of Mars at the time shown. The 'Fav. Hem' column shows the Hemisphere in which the conjunction was best observed (Northern, Southern and/or Equatorial). The expression 'Not high N/S Lats' indicates that observers at latitudes further North than about 45°N (or further South than about 45°S) will have found the conjunction difficult or impossible to view because of low altitude and/or bright twilight.
In the 'When Visible' column, a distinction is made between Dawn/Morning visibility and Dusk/Evening visibility; the terms Dawn/Dusk refer specifically to the twilight period before sunrise/after sunset, whilst the terms Evening/Morning refer to the period after darkness falls/before twilight begins (some conjunctions take place in darkness, others do not, depending upon latitude). The 'Con' column shows the constellation in which the planets were positioned at the time of the conjunction.
To find the direction in which the conjunctions were seen on any of the dates in the table, note down the constellation in which the planets were located ('Con' column) on the required date and find the constellation's rising direction (for Dawn/Morning apparitions) or setting direction (for Dusk/Evening apparitions) for your particular latitude in the Rise-Set direction table.
A table of planetary conjunctions involving Mars from 2016 to 2020 can be seen here (67 KB).
Although any given conjunction takes place at a particular instant in time, it is worth pointing out that, because of the planets' relatively slow daily motions, such events are interesting to observe for several days both before and after the actual conjunction date.
There are in fact two methods of defining a planetary conjunction date: one is measured in Right Ascension (i.e. perpendicular to the celestial equator) and the other is measured along the ecliptic, which is inclined at 23½° to the Earth's equatorial plane (this is due to the tilt of the Earth's axis in space). An animation showing how conjunction dates are determined by each method can be found on the Jupiter-Uranus 2010-11 triple conjunction page. Although conjunction dates measured along the ecliptic can be significantly closer, the Right Ascension method is the more commonly used, and it is the one which is adopted here.
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Aquarus, Pisces, Aries & Taurus:
Aries & Western Taurus
Pisces & Square of Pegasus
Eastern Aquarius & Western Pisces
Aquarius, Pisces, Aries & Taurus (click on the thumbnails for their full-size versions: 105 KB, 56 KB and 201 KB respectively). Photographs showing the region of the night sky through which Mars passed from May 2020 to March 2021. In the Aquarius photo stars are visible down to an apparent magnitude of about +7.5. In the Pisces photo the limiting magnitude is about +6.5 whilst in the Aries & Western Taurus photo it is about +7.5. Note that the three photographs do not have the same scale because of the differing camera lens settings and image resolutions. Bottom: Diagram showing the areas of the 2020-21 star chart which are covered by the photographs (click on the thumbnail for the full-size version,56 KB).
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Moon near Mars Dates,
October 2019 to August 2021
The Moon is easy to find, and on one or two days in each month, it passes Mars in the sky. The following tables list the dates on which the Moon passed near the planet during its 2019-21 apparition:
Moon near Mars dates for the period from October 2019 to August 2021 (click on thumbnail for full-size table, 64 KB). The Date Range shows the range of dates worldwide (allowing for Time Zone differences across East and West hemispheres). Note that the Date, Time and Separation of conjunction (i.e. when the two bodies are at the same Right Ascension) are measured from the Earth's centre (geocentric) and not from the Earth's surface. All times are Universal Time [UT], which is equivalent to GMT. The Sep. & Dir. column gives the angular distance (separation) and direction of the planet relative to the Moon, e.g. on June 12th 2020 at 23:54 UT, Mars was positioned 2°.7 North of the Moon's centre. The Moon Phase shows whether the Moon was waxing (between New Moon and Full Moon), waning (between Full Moon and New Moon), at crescent phase (less than half of the lunar disk illuminated) or gibbous phase (more than half but less than fully illuminated).
The Moon and Mars in Conjunction Some conjunctions can be really quite wide (click on the thumbnail for the full-size image, 8 KB). In this particular conjunction, photographed by the writer in October 2007, the waning gibbous Moon passed 4°.4 to the North of Mars in the pre-dawn sky.
The Moon moves relatively quickly against the background stars in an Eastward direction, at about its own angular width (0º.5) each hour (about 12º.2 per day). Because it is relatively close to the Earth, an effect called parallax causes it to appear in a slightly different position (against the background stars) when seen from any two locations on the globe at any given instant; the further apart the locations, the greater the Moon's apparent displacement against the background stars. Therefore, for any given date and time listed in the table, the Moon will have appeared closer to Mars when seen from some locations than others. For this reason, the dates shown in the table should be used only for general guidance.
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Copyright Martin J Powell July 2019
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