The Venus Morning Apparition

of 2015 to 2016

by Martin J. Powell

The path of Venus through the zodiac constellations during the planet's morning apparition in 2015-16 (click on thumbnail for the full-size image, 46 KB). A version with constellation labels can be seen here (60 KB). Constellation names are shown in their three-letter abbreviated format - the full names are listed here. Zodiac constellations are labelled in green and non-zodiac constellations in grey. The numbers along the sides of the chart (Right Ascension and Declination) are co-ordinates of celestial longitude and latitude which are used to locate the position of a celestial body in the night sky. A print-friendly version is available here (21 KB).

Venus passed through inferior conjunction (when it was positioned between the Earth and the Sun) on August 15th 2015. At this time the planet was positioned 7º.8 South of the Sun's centre (i.e. its ecliptic latitude = -7º.8). Observers situated South of about 36º South were able to glimpse Venus from inferior conjunction day itself, after a period of just a few days out of view in the solar glare. Here the planet was positioned sufficiently far from the Sun - and sufficiently far above the horizon - for it to be viewed briefly in the bright dawn twilight, low down over the Eastern horizon. Elsewhere, Venus was seen to swiftly enter the dawn sky as a 'Morning Star' from mid- to late August, visible in the Eastern sky around 30-60 minutes before sunrise (the exact period depending upon the observer's latitude).

The planet was moving retrograde (East to West) among the stars of South-western Leo, the constellation of the Lion, at this time. Venus was positioned at a relatively close 0.31 Astronomical Units (AU) from the Earth (46.3 million kms or 28.8 million statute miles), a distance which would continually increase over the next 8½ months, through to the end of the apparition.

Venus entered Cancer, the Crab, on August 18th, reaching a solar elongation (angular distance from the Sun) of 10° West on the following day and 15° West on the 24th. The planet shone at an apparent magnitude of -4.1 and its apparent diameter (its angular width as seen from the Earth) was a sizeable 55" (i.e. 55 arcseconds, where 1 arcsecond = 1/3600th of a degree). In late August Venus rose about 1½ hours before sunrise, barely gaining any significant altitude (or elevation, i.e. the angle above the horizon) before disappearing from view into the twilight.

Venus, the 'Morning Star' pictured high in the dawn sky during a particularly cold winter in the British Isles in December 2010 (click on the thumbnail for the full-size picture, 144 KB).

As it pulled away from the Sun, telescopes pointed towards Venus showed a large, slender, Eastward-facing crescent, rippling in the Earth's turbulent atmosphere. The planet's phase (i.e. the percentage of the disk which was illuminated) was only around 5% (phase = 0.05). At this early stage of the apparition, dedicated telescopic observers of Venus now began their search for the elusive Ashen Light, which is a faint glowing of the night side of Venus through its thick clouds. The phenomenon is believed to be caused either by the planet's surface glowing red hot (due to its extremely high surface temperature) or due to electrical activity in its dense atmosphere. Observers searching for the Light will normally use ultraviolet and/or infrared filters in order to help reveal it, an occulting bar often being used to block the bright, visually-intrusive crescent from view. Observers in Equatorial latitudes were best placed to view the Light at this stage of the apparition due to the planet's higher altitude before sunrise.

On August 29th the planet Mars passed 9°.5 North of Venus in the first of five planetary conjunctions which took place during the 2015-16 morning apparition. A planetary conjunction takes place whenever two planets attain the same celestial longitude in the night sky (i.e. they appear to 'line up' when seen from the Earth). This first of two conjunctions with the Red Planet during the period was a poor one, the planets being widely separated and difficult to see in the dawn twilight. Details of this and the other four planetary conjunctions involving Venus are given in the 'planetary conjunctions' section below.

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By the beginning of September Venus' apparent diameter had shrunk slightly to around 50" (50 arcseconds). The planet's apparent diameter would continue to shrink throughout the apparition, as it slowly receded from the Earth in space (click here to see how Venus typically appears through a small telescope at various phases).

Venus passed 2°.3 South of the star Acubens ( Cnc or Alpha Cancri, mag. +4.2), at the South-eastern corner of the Crab constellation's lambda-shaped () pattern, on September 3rd. Since entering Cancer the planet had been describing a slow, counter-clockwise loop against its background stars, initially moving in a West-North-westerly direction but now moving North-North-westerly. On September 5th the planet's Westerly motion ceased as it reached a stationary point some 2° South of Acubens. Venus briefly travelled Northwards before curving around towards the North-North-east, when it again passed Acubens - this time passing 1°.9 South of it - on September 6th.

Venus attained its greatest brilliancy for this apparition (at mag. -4.5) on September 21st. This was the position in the planet's orbit when its phase, its apparent size and its apparent magnitude combined to best visual effect, as seen from the Earth. At greatest brilliancy in the 2015-16 morning apparition, Venus was positioned 40° West of the Sun with a 27% illuminated crescent (phase = 0.27) and an apparent diameter of 37".8.

On September 23rd the planet re-entered Leo, this time moving prograde or direct (West to East) which is the prevailing direction of travel of the planets in the night sky (during this particular apparition, Venus would spend some 93% of the time moving direct).

October commenced with Venus positioned 0°.6 North of the star Subra ( Leo or Omicron Leonis, mag. +3.5), at the tip of the Lion's foreleg.

In the second week of October Venus, Mars and Jupiter formed an eye-catching grouping in South-western Leo, with the waning crescent Moon joining the group between October 8th and 10th. Both Mars (mag. +1.7) and Jupiter (-1.6) were in the early stages of their respective apparitions, having emerged from behind the Sun around late July (Mars) and mid-September (Jupiter).

On October 8th most of the world saw the Moon pass very close to Venus. However, from Eastern Australia the Moon was seen to pass in front of the planet, obscuring it from view, in an event called a lunar occultation. Venus disappeared behind the Moon's bright limb and, up to 80 minutes later, re-appeared from behind its dark limb. Further details of this event can be found by following the link in the 'Moon near Venus Dates' section below.

On October 9th Venus passed 2°.5 South of Leo's brightest star Regulus ( Leo or Alpha Leonis, mag. +1.4). Also on the same day, the planet Mercury (mag. +0.9) joined the grouping, emerging into the dawn sky at the start of its third and final morning apparition of 2015. The elusive planet came closest to the other three planets around October 11th, forming a four-planet alignment measuring some 29° across. Mercury reached its greatest elongation from the Sun (18°.1 West) on October 16th.

Around mid-October, observers at high and mid-Northern latitudes saw Venus attain its highest altitude in the sky before sunrise for the 2015-16 apparition. At latitude 60° North, the planet rose nearly five hours ahead of the Sun, attaining an altitude of 29° above the South-eastern horizon at 30 minutes before sunrise. For mid-Northern observers, the planet rose four hours before the Sun, reaching a decent 34° above the South-eastern horizon at 30 minutes before sunrise. For naked-eye observers in the Northern hemisphere, the 2015-16 apparition was the best of Venus' five morning apparitions over the planet's 8-year cycle (for more details, see the accompanying article describing The Venus 8-year Cycle). From Northern latitudes Venus would attain higher-than-average altitudes above the horizon at dawn than any of the other four morning apparitions. Conversely it was the worst morning apparition for Southern hemisphere observers, the planet typically attaining lesser altitudes above the horizon at dawn than in the other morning apparitions.

Over the next fortnight Venus, Mars and Jupiter formed a variety of geometric shapes in the night sky, clustered in Southern Leo. On October 17th Mars and Jupiter experienced their own planetary conjunction, coming to within 0°.4 of each other, with Venus positioned some 6°.7 to the West of the pair. The three appeared as a long isosceles triangle pointing Westwards, with Venus at the apex. On October 20th the three planets formed an East-West line some 5°.7 long, just South of the Lion's body. On October 23rd the three formed a low, flat isosceles triangle measuring 4°.6 wide at the base with sides 2°.3 long. The trio were positioned a short distance to the West of the star Leo (Sigma Leonis, mag. +4.0), at the foot of the Lion's hind leg. On October 25th Venus and Jupiter formed a right-angled triangle with Mars at around 2140 UT. Venus and Jupiter were 1° apart, with Mars positioned 3°.4 to the East.

At around 03 hours UT on the following day (October 26th) Venus, Mars and Jupiter formed another isosceles triangle, this one lying on its side with a base measuring 1° wide and with sides of 3°.5. The triangle pointed East, towards the constellation of Virgo. Venus crossed the ecliptic (the path of the Sun, which the Moon and planets follow very closely) in a Northward direction at about 7 hours UT on the same day. About an hour later Venus passed 1°.1 South of Jupiter in a planetary conjunction which favoured Northern hemisphere observers. Around 10 hours UT on the same day, Venus reached its greatest Western elongation (46°.4 West of the Sun), positioned 3°.3 West of Leo and 16° ESE of Regulus. Venus' apparent magnitude had faded slightly to -4.2 and its apparent diameter had reduced to 24".1. Although the planet's greatest elongation from the Sun took place on October 26th, Venus was in fact positioned at precisely 46°.4 elongation for a nine-day period from October 22nd through to 31st.

Telescopes now showed Venus' disk half-illuminated (phase = 0.50). Theoretically, greatest elongation is the time at which the planet's terminator (the line separating the light and dark sides of the planet) appears perfectly straight through telescopes, essentially dividing Venus into two perfect halves; this is known as the dichotomy. However, telescopic observers often report the straight terminator several days earlier or later than the greatest elongation date. Interestingly, the date of dichotomy is usually reported early in evening apparitions and late in morning apparitions. The precise reason for this phenomenon - which is referred to as Schröter's Effect - is not known, however it may simply be due to the fact that the precise moment of dichotomy cannot be determined by an observer to within an accuracy any better than a few days.

On October 28th the three planets formed another isosceles triangle, straddling the Lion's rear paw. This time the triangle was just 0°.9 high, with a base measuring 4°.6 wide and sides 2°.5 long.

In late October, observers situated at Northern tropical latitudes saw the planet attain its highest altitude before sunrise for the 2015-16 morning apparition. At 30° North, Venus rose 3½ hours ahead of the Sun, reaching 38° above the ESE horizon at half-an-hour before sunrise. Elsewhere the planet rose five hours before sunrise at 60° North, 4¼ hours before sunrise at 50° North and three hours before the Sun at Equatorial latitudes. Mid-Southern latitudes saw the planet rise two hours ahead of the Sun. In fact, when assessed in terms of horizon altitude and visibility duration before sunrise, the 2015-16 morning apparition of Venus was best seen overall from Northern Tropical latitudes.

Venus entered Virgo, the Virgin, on November 2nd. Around 1 hour UT on November 3rd the three planets formed a long, 6°.9-high isosceles triangle, 0°.7 wide at the base, the apex pointing WNW towards Regulus. At around 16 hours UT on the same day Venus, moving at an apparent daily rate of 0°.9 against the background stars, passed 0°.7 to the South of slower-moving Mars in the third planetary conjunction of the 2015-16 apparition. The two planets were positioned 46° West of the Sun, Venus having hardly changed its solar elongation since attaining greatest elongation eight days previously.

For Equatorial observers, early November saw the planet attain its highest altitude above the horizon before sunrise for the current apparition. Here Venus rose 2¾ hours before the Sun, reaching 34° above the Eastern horizon some 30 minutes ahead of sunrise.

By the end of the first week of November, Venus and Mars had pulled sufficiently Eastwards from Jupiter so that no more geometric formations took place between the three. However, Venus, Mars and the star Zavijah ( Vir or Beta Virginis, mag. +3.6) formed an interesting straight line at around 17 hours UT on November 5th. The line, 1°.8 in length, was small enough to be contained within a telescopic wide-field (low magnification) eyepiece view and easily within a binocular field-of-view. Venus passed just 16' (16 arcminutes, where 1 arcminute = 1/60th of a degree) North of Zavijah itself on November 6th.

At around 1040 UT on November 7th Venus, Mars and the waning crescent Moon appeared in a tight 2°-wide grouping, the trio forming a right-angled triangle centred around Zavijah. With the inclusion of Jupiter to the North-west, the four produced an interesting line-up in the Eastern sky measuring some 11° across.

Venus crossed the celestial equator (where the declination of a celestial body is 0°) heading Southwards on November 11th, the planet now rising due East across the inhabited world. On November 13th Venus passed just 4' (4 arcminutes, or 0°.06) North of the star Zaniah ( Vir or Eta Virginis, mag. +3.8) then five days later (18th) 1°.1 South of the double star Porrima or Arich ( Vir or Gamma Virginis, mag. +3.5).

Greatest elongation day long having passed, telescopes showed a 60% illuminated (i.e. slightly gibbous) phase in mid-November; the phase would remain gibbous through the rest of the apparition. The apparent diameter had now reduced to around 20" and the planet shone at an apparent visual magnitude of -4.2.

Venus passed just 15' (15 arcminutes, or  0º.25) North of another double-star, Theta Virginis ( Vir, mag. +4.4) on November 25th. Three days later the planet passed 4º.5 North of Virgo's brightest star, Spica ( Vir or Alpha Virginis, mag. +1.0), a blue-white star which dominates the South-eastern region of the constellation.

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In early December at 60° North latitude, Venus was rising 4¾ hours before the Sun, attaining an altitude of 19° in the SSE at 30 minutes before sunrise. At 50° North the planet rose four hours before the Sun, reaching an altitude of  25° in the South-east at 30 minutes before sunrise. At 30° North Venus rose 3¼ hours before the Sun, reaching 32° altitude in the South-east at 30 minutes before sunrise. At the Equator the planet rose 2¾ hours ahead of the Sun, climbing to 33° high in the ESE at 30 minutes before sunrise and at mid-Southern latitudes the planet rose two hours before the Sun and reached 19° high in the East at a half-hour before sunrise.

Since inferior conjunction Venus had been receding from the Earth at an average rate of about 933,000 kms (579,000 miles) per day. On December 7th, the planet was positioned at precisely 1.00 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).

At around 16 hours UT on December 7th, observers located in Alaska (USA) and North-western Canada witnessed the 25-day old Moon passing in front of Venus in the second lunar occultation of the planet's morning apparition. South of the North-western American continent, along the Earth's dawn terminator, the crescent Moon was seen to pass up to 1°.5 to the North of the planet.

The last reasonably-bright star which Venus passed before leaving Virgo was Vir (Kappa Virginis, mag. +4.1), located near the constellation's South-eastern border with Libra, the Balance. Venus passed 0º.6 South of the fourth-magnitude star on December 9th.

Venus entered Libra on December 11th, passing 2°.0 North of the double-star Zuben Elgenubi (² Lib or Alpha² Librae, mag. +2.8) on December 17th. On December 26th the planet, now shining at magnitude -4.0, passed 2º.3 South of the star Zuben Elakrab ( Lib or Gamma Librae, mag. +4.0) and then 1º.4 South of the star Theta Librae ( Lib, mag. +4.1) on December 30th. On the final day of the year Venus passed 4º.1 North of the star Dschubba ( Sco or Delta Scorpii, mag. +2.2), in the neighbouring constellation of Scorpius, the Scorpion.

Venus entered Scorpius at around 0740 hours UT on January 1st, passing 0°.9 North of the striking double-star Graffias (¹ Sco or Beta-1 Scorpii, combined mag. +2.6) much later that day.

Over the course of 2¾ hours on January 2nd, Venus passed the two Omegan stars Jabhat al Akrab (¹ Sco or Omega-1 Scorpii, mag. +3.9) and Omega-2 Scorpii (² Sco, mag. +4.3). Together with Dschubba, Graffias and the quadruple star Jabbah ( Sco or Nu Scorpii, mag. +4.0), they form a distinctive asterism in Northern Scorpius. Venus passed 1º.7 North of the blue-white star Jabhat al Akrab (Arabic for 'forehead of the Scorpion') at 0540 UT and then 1º.9 North of the yellow star Omega 2 Scorpii at 0825 UT. The following day (3rd) Venus passed 18' (18 arcminutes or 0º.3) North of the aforementioned fourth-magnitude star Jabbah.

In the early hours (UT) on January 5th Venus passed 6º North of the variable star Alniyat ( Sco or Sigma Scorpii, mag. +2.9v) before entering the non-zodiacal constellation of Ophiuchus, the Serpent-Bearer, around midday UT. On January 6th the planet passed 6º.4 North of the Scorpion's brightest star Antares ( Sco or Alpha Scorpii, mag. +1.0v), which shines with an unmistakable orange-red hue.

Venus experienced its penultimate planetary conjunction of the apparition on January 9th, when it passed just 5' (5 arcminutes or 0º.08) North of Saturn. From the Northern hemisphere, this very close conjunction was also the last visible conjunction of  Venus' morning apparition. Saturn was in the very early stage of its 2015-16 apparition, having emerged into the dawn sky only a few weeks earlier. It was some five months away from opposition (when it would be seen at its best) but its wide-open rings already made it a beautiful - albeit small - telescopic sight.

Around mid-January, observers at mid-Southern latitudes saw Venus attain its highest altitude in the sky before sunrise for the 2015-16 apparition. At 35° South, the planet rose 2½ hours before the Sun, reaching an altitude of around 22° high in the ESE at 30 minutes before sunrise. Elsewhere, Venus rose in the SSE two hours before sunrise (at 60° North), in the South-east some 2¼ hours before sunrise (at 50° North and 30° North) and in the ESE some 2½ hours before sunrise (at the Equator). From higher Northern latitudes, the planet was now beginning to rise in twilight; elsewhere the planet rose in darkness.

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Whilst in Ophiuchus, the only reasonably-bright star encountered by Venus was third-magnitude Theta Ophiuchi ( Oph, mag. +3.2), which the planet passed 3º.2 to the North of on January 16th. Having spent a fortnight in Southern Ophiuchus, Venus entered Sagittarius, the Archer, on January 20th.

For a period of 16 hours between January 24th and 25th, Venus passed about 2º North of the sixth-magnitude gaseous nebula commonly called the Lagoon Nebula or M8 (NGC 6523). With an apparent dimension of 90' by 40', the nebula is visible to the naked-eye from dark sites and is a spectacular sight through larger telescopes - particularly those fitted with nebular filters.

From the third week of January, Mercury emerged from the solar glare into its first morning apparition of 2016, the first of six apparitions (three morning and three evening) which took place during the year. Currently moving retrograde, Mercury reached a Westerly stationary point on January 26th, positioned 21º from the Sun, looping around just to the North of the Archer's head. Venus - now magnitude -3.9 - approached Mercury from the West, the pair moving closer to each other over the next fortnight. On January 26th the two inferior planets were positioned some 12º.4 apart.

Over the next ten days or so, Venus passed just to the North of Sagittarius' famous asterism, the Teapot, which comprises eight stars of third-magnitude or brighter. On January 25th Venus passed 8º.0 North of the star variously named Nash, Al Nasl or Alnasr ( Sgr or Gamma Sagittarii, mag. +3.0). On January 27th the planet passed 7º.4 North of the star Kaus Meridionalis ( Sgr or Delta Sagittarii, mag. +2.7) which marks the centre of the Archer's bow.

On January 28th Venus attained its most Southerly declination for this apparition, at -22° 27' (-22°.45 in decimal format). Across the inhabited world the planet now rose at its most Southerly position on the local horizon. This would typically be towards the South-east at latitudes far away from the Equator and towards the ESE at Equatorial latitudes.

On January 29th Venus passed 3º.0 North of the star Kaus Borealis ( Sgr or Lambda Sagittarii, mag. +2.8) which marks the top of the Teapot asterism (and the top of the Archer's bow). On January 30th the planet passed 1º.4 North of the 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 beautifully resolved in telescopes.

With the arrival of February Venus began to pass North of the four stars which form the 'handle' of the Teapot. The planet passed 4°.6 North of Phi Sagittarii ( Sgr, mag. +3.1) on February 1st and 4°.0 North of the constellation's second-brightest star Nunki ( Sgr or Sigma Sagittarii, mag. +2.0) on February 3rd. Later that same day and away from the Teapot, Venus passed 1°.1 South of the star ² Sgr (Xi-2 Sagittarii, mag. +3.5), which marks the forehead of the Archer figure. The planet passed 7°.7 North of Ascella ( Sgr or Zeta Sagittarii, mag. +2.6), at the base of the Teapot's handle, on February 4th. The following day (5th) the planet passed 22' (22 arcminutes or 0°.36) South of the star Sgr (Omicron Sagittarii, mag. +3.7) which marks the eye of the Archer. Finally, later that same day, the planet passed 5°.6 North of Tau Sagittarii ( Sgr, mag. +3.3) which marks the Easternmost point of the Teapot.

From early February, observers situated at high-Northern latitudes were the first to lose sight of Venus, as the planet slipped into the bright dawn twilight. Over the next 3½ months the apparition would slowly end in a Southward direction, from the Northern hemisphere into the Southern.

In the early hours (UT) of February 6th Venus passed 1°.0 South of the star Albaldah ( Sgr or Pi Sagittarii, mag. +2.9), positioned at the top of the Archer's head. At around 0830 UT Venus (mag. -3.9), Mercury (+0.0) and the waning crescent Moon formed an equilateral triangle with sides 4°.8 long, visible from Southern Tropical latitudes (the best view was had from Central South America, where the triangle rose in darkness). Elsewhere the triangle was not quite equal-sided but more isoscelene, the Moon being positioned near the star ¹ Sgr (Rho-1 Sagittarii, mag. +3.9). The following day (7th) Mercury reached its greatest Western elongation from the Sun, at 25°.5, whilst Venus' solar elongation fell below 30°. Venus was now moving at its fastest apparent rate of motion against the background stars for the current apparition, at about 1°.2 per day.

By the time Venus passed 3°.5 to the North of the star 52 Sagittarii (mag. +4.6) on February 11th, the planet was positioned just 4° away from Mercury. For the next five days the two planets travelled Eastwards together, more-or-less equidistant from each other, as if in some kind of celestial procession. On February 13th Mercury crossed the Sagittarian boundary into Capricornus, the Sea-Goat. Venus crossed the ecliptic heading Southwards on February 14th, then entered Capricornus on the 17th, some 55 hours after Mercury.

From around February 16th Mercury began to pull away Eastwards from Venus, heading back in towards the Sun and widening the gap between the two. By the time Mercury's apparition ended around March 6th, the angular distance between the two had extended to 9°.

Venus passed 4º.9 South of the variable and multiple star Dabih ( Cap or Beta Capricorni, mag. +3.0v) on February 19th, then, at around 1307 UT on February 28th, passed just 1'.6 (1.6 arcminutes or 0º.02) South of the star Theta Capricorni ( Cap, mag. +4.0). This was so close together that the naked-eye could not split the two; they effectively appeared as one 'star'. Through binoculars the two appeared as a striking double-star with white components of wildly differing magnitudes (-3.9 and +4.0).

By late February Venus' elongation had reduced to 25° and it appeared only slightly gibbous through telescopes, showing a 90% illuminated phase and a disk-diameter of around 13", i.e. only half the size it had been in mid-October and a third of the size it had been in mid-September. With such a small disk size and a narrow solar elongation, little could now be discerned in the way of the planet's characteristic cloud markings.

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On March 3rd, Venus passed 0º.6 North of the star Iota Capricorni ( Cap, mag. +4.3) and on March 6th, 1º.8 North of Nashira ( Cap or Gamma Capricorni, mag. +3.7). The planet passed 1º.8 North of the constellation's brightest star, a variable star named Deneb Algiedi ( Cap or Delta Capricorni, mag. +2.9v), on March 7th.

In early March, observers at mid-Northern latitudes lost sight of Venus as it slipped into the bright ESE horizon, bringing the apparition to an end from these locations. For much of the remainder of the Northern hemisphere the 'observing window' had reduced to less than an hour. At Equatorial and Northern Tropical latitudes the planet rose between 1¼ and 1½ hours before the Sun, reaching around 8°-15° high in the ESE at 30 minutes before sunrise. Mid-Southern hemisphere observers now had a rapidly shortening window in which to observe the planet, despite its still rising in darkness. At 35° South, Venus rose two hours ahead of the Sun, attaining about 17° in altitude in the Eastern sky at 30 minutes before sunrise.

Venus entered Aquarius, the Water-Carrier, on March 10th, passing 1º.1 North of the star Iota Aquarii ( Aqr, mag. +4.2) on March 11th. Three days later (14th) Venus passed 4º.1 South of the star Ancha ( Aqr or Theta Aquarii, mag. +4.1). Between March 15th and 17th the planet was positioned about 10º South of Aquarius' best-known identifier, the so-called 'Steering Wheel' asterism.

Venus' final planetary conjunction was a close but difficult one, only visible from the Southern hemisphere and Equatorial latitudes. On March 20th Venus - now magnitude -3.8 - passed 0º.5 North of eighth-magnitude Neptune. The closeness of the two planets - easily contained within the field-of-view of telescopes at high magnifications - made it an ideal opportunity for those who had never seen our most distant Solar System planet to locate it with relative ease, using Venus as a bright, naked-eye locator-beacon.

Now just 20° West of the Sun, Venus passed 1º.0 South of the star Lambda Aquarii ( Aqr, mag. +3.9) on March 21st, a star which the planet occulted during its 2014 morning apparition. The planet passed just 22' (22 arcminutes or 0°.36) South of the star Phi Aquarii ( Aqr, mag. +4.2) on March 26th. Positioned at the top of the Water Bearer's amphora, this star will also be occulted by Venus during the course of its 2028 evening apparition.

From March 26th through to April 2nd, Venus was positioned about 8º South of the Circlet of Pisces, at the Western end of Pisces, the Fishes. The Circlet comprises six stars of fourth and fifth magnitude; under twilit or light-polluted conditions it is likely that some or all of them will not be seen with the naked-eye.

Venus entered Pisces on April 1st. At around 0830 UT on April 6th the planet was occulted by the Moon for a third and final time for this apparition, the event being seen in darkness from North-western Africa.

Telescopes now showed a tiny Venusian disk around 10" across and a phase of around 98% - so slightly gibbous that the planet almost appeared 'full'. Venus crossed the celestial equator and entered the Northern celestial hemisphere on April 8th, positioned to the ESE of the Circlet. Like in the previous November, the planet was again seen rising due East, but this time only from Equatorial and Southern hemisphere latitudes. On April 11th the planet briefly exited Pisces and headed into the constellation of Cetus, the Whale, clipping its North-western corner. Venus spent just three days in Cetus before re-entering Pisces on April 14th.

By mid-April Venus' solar elongation had reduced below 15° and the planet was rising in twilight across the inhabited world. Mid-Southern hemisphere observers were still able to see the planet rising in twilight an hour before the Sun, although it attained just 5° in altitude at 30 minutes before sunrise.

Venus (mag. -3.9) passed 0°.9 South of the planet Uranus (+5.9) on April 22nd, however with the planets positioned at just 12° from the Sun, only Venus was bright enough to cut through the twilight. Observers at Northern Tropical latitudes lost sight of Venus around this time, the planet disappearing into the bright Eastern horizon. Now, only Equatorial and Southern hemisphere latitudes were still able to observe the 'Morning Star', very low down in the Eastern sky at dawn. The planet entered Aries, the Ram, at the close of the month on April 30th, at which time the planet's solar elongation fell below 10° and it was fast heading out of view from all except the Southernmost latitudes.

Venus passed 0°.4 North of Mercury on May 13th in an unobservable conjunction just 6° away from the Sun. By the middle of May, the planet became lost from view from the remaining latitudes, bringing the planet's 2015-16 morning apparition to a formal close. The planet slipped unseen into Taurus, the Bull on May 19th.

Venus reached superior conjunction (passing behind the Sun as seen from the Earth) in Northern-central Taurus on June 6th 2016, positioned at a very distant 1.735 AU from the Earth (259.5 million kms or 161.2 million statute miles).

Having passed from the morning to the evening sky, Venus remained out of view - lost in the solar glare - for about two months, as it made its slow passage on the far side of its orbit from the Earth. The planet became visible once again from around early July 2016, when it was seen shortly after sunset from Equatorial latitudes as an 'Evening Star' in the WNW, heralding a new evening apparition (2016-17) which lasted through to March 2017.

 [Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]

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Venus Conjunctions with other Planets,

2015-2016

The October 26th 2015 conjunction between Venus and Jupiter took place on the same day as Venus' greatest Western elongation - in other words, about as far from the Sun as these two planets can appear at conjunction. For Northern hemisphere observers, the fact that the 2015-16 morning apparition was the best of the five morning apparitions in Venus' 8-year cycle meant that this conjunction was also the most ideally-placed for them.

A significant factor in determining whether a morning conjunction is 'easy' or 'difficult' is the altitude that the fainter planet (in this case Jupiter) attains before it disappears from view in the brightening dawn twilight. In the October 2015 conjunction, observers at latitude 60° North saw the two planets attain a significant altitude of about 30° over the South-eastern horizon when Jupiter disappears from view in the twilight. The altitudes and directions at other latitudes were as follows: 35° high in the South-east at 50° North, 41° high in the ESE at 30° North and 38° high in the East at the Equator. In the Southern hemisphere the altitudes were lower at this time of year due to the shallow angle of the ecliptic to the Eastern horizon at dawn. Mid-Southern latitudes saw the planets attain an altitude of just 19° above the ENE horizon when Jupiter disappeared from view. The altitude worsened as one moved further South, the conjunction not being visible at all from high-Southern latitudes.

A Dawn Venus-Jupiter Conjunction (click on the thumbnail for the full-size picture, 129 KB). A planetary conjunction between Venus and Jupiter captured through drifting clouds in the early morning hours of August 18th 2014. The two planets were separated by a distance of just 12 arcminutes (0°.2).

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Measured in terms of apparent magnitude, perhaps the next best planetary conjunction of the apparition was that with Saturn on January 9th 2016, when Venus (mag. -3.9) passed just 5' (5 arcminutes or 0º.08) to the North of Saturn.(+0.6). Although a very close conjunction which was nicely seen through telescopes, the planets' relatively narrow solar elongation (36º W) ensured that neither planet was placed particularly high in the sky by the time Saturn disappeared from view. At 60° North the pair attained an altitude of just 7° above the SSE horizon when the ringed planet disappeared from view, whilst at 50° North they reached just 13° high. Equatorial and Tropical latitudes had the best view; at 30° North they attained 23° high in the South-east whilst at the Equator they reached 29° high in the ESE. Again, the altitudes progressively worsened as one moved Southwards, reaching 22° above the ESE horizon at 35° South and 13° high at 45° South.

There were two conjunctions of Venus with Mars during the apparition, the Red Planet being no brighter than magnitude +1.7 on both occasions. A poor, nine-degree wide conjunction on August 29th 2015 was only visible South of mid-Northern latitudes and North of mid-Southern latitudes. The second, on November 3rd, took place only a week after the Venus-Jupiter conjunction described above. Consequently it was also ideally placed for Northern hemisphere observers, the planets' location in Virgo positioning the ecliptic at a steep angle to the local horizon at dawn. The narrow separation between the two planets (0°.7) allowed them to be fitted within the field-of-view of a telescope eyepiece at low- or medium power. This latter conjunction was less well-seen in the Southern hemisphere, being visible in twilight at around 35° South and not visible at all South of latitude 49° South.

Venus' last conjunction of the period took place on March 20th 2016, when Venus (mag. -3.8) passed only 0º.5 North of Neptune (+7.9). Since Neptune is the faintest of the observable planets in the night sky and Venus is the brightest, it follows that this conjunction was a technically difficult one to observe, regardless of the solar elongation. Telescopes are required to observe such events; binocular users will find the brilliance of Venus prohibits comfortable viewing. Even through telescopes Venus' brilliance means that it must be positioned outside the telescopic field of view to enable Neptune to be comfortably seen. This particular conjunction could only be seen from latitudes South of about 5º North. Although rising in darkness, at the Equator the two planets were placed a mere 4° above the horizon as Neptune disappeared from view in the twilight, whilst even in the favourable Southern hemisphere the pair were at best placed only 6° high at Southern Tropical latitudes. Here the conjunction required sheer dedication on the part of the observer, the two planets only being visible for about 15 minutes!

The five planetary conjunctions with Venus which were viewable during the 2015-16 morning apparition are summarised in the table below.

Venus conjunctions with other planets during the 2015-16 morning apparition (click on the thumbnail for the full-size table, 22 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 Venus, e.g. on 2015 Oct 6, Jupiter was positioned 1°.1 North of Venus 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) would most likely have found the conjunction difficult or impossible to observe because of low altitude and/or bright twilight.

In the 'When Visible' column, a distinction is made between Dawn and Morning visibility; the term Dawn refers specifically to the twilight period before sunrise, whilst the term Morning refers to the period 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 your particular latitude in the Rise-Set direction table.

The table is extracted from two other tables showing Venus conjunctions with other planets from 2010 to 2020 on the Venus Conjunctions page.

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. along 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 are technically more accurate (separations between planets 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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Moon near Venus Dates,

September 2015 to April 2016

The Moon is easy to find, and on one or two days in each month, it passes Venus in the sky. Use the following tables to see on which dates the Moon passed near the planet between September 2015 and April 2016:

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 Venus 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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Credits

• The dates of Venus' constellation boundary crossings and its directions, altitudes and visibility durations were determined from the commercial software RedShift 5 by Maris Technologies Ltd. The planetary conjunction details and the times and separations of the lunar conjunctions with Venus (Moon near Venus dates) were obtained from RedShift 5 using the 'Conjunctions' option of the 'Sky Diary'.

• The information regarding the Venus, Mars and Moon trio of November 7th 2015 was obtained from the website The Sky and Its Phenomena by Italian amateur astronomer Pierpaolo Ricci.

Copyright  Martin J Powell  August 2015