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The Position of Jupiter in the Night Sky:
2006 to 2008
by Martin J. Powell
The path of Jupiter against the background stars of Libra, Scorpius, Ophiuchus and Sagittarius from December 2005 to January 2009, with positions marked at the start of each month (click on the thumbnail for the full-size image, 79 KB). Periods when the planet was unobservable (i.e. when it was too close to the Sun, or passed behind it) are indicated by a dashed line. Hence the planet became lost from view (in the evening sky) in early November 2006 and became visible again (in the morning sky) in early December 2006.
The chart shows to good effect how the shape of a planet's apparent looping formation transforms as it moves through the zodiac. In 2006, Jupiter described a conventional North-facing loop. In 2007, the loop became 'hybrid' (half loop, half zig-zag) and became a full zig-zag as it crossed the ecliptic (heading Southwards) in 2008.
The star map applies to observers in the Northern hemisphere (i.e. North is up); for the Southern hemisphere view, click here (83 KB; the Southern hemisphere chart should be used by observers situated south of the Tropic of Capricorn [23½° South]). The Milky Way is shown in dark grey; 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 (38 KB) and Southern hemisphere (40 KB) views.
Throughout 2006, Jupiter was seen in the constellation of Libra, the Scales, where it had been situated since late 2005. The planet entered Scorpius, the Scorpion, in early December 2006 and entered the non-zodiac constellation of Ophiuchus, the Serpent Bearer, at the end of that same month.
Jupiter's entire 'hybrid' loop formation was described within the boundary of Ophiuchus, after which it continued Eastwards (direct motion) through to early December 2007, when the planet entered Sagittarius, the Archer. Jupiter remained in Sagittarius until early January 2009, when it crossed the boundary into Capricornus, the Sea Goat (for details, see the 2009-2011 page).
Jupiter reaches opposition to the Sun (when it is closest to the Earth and brightest in the sky for the year) every 398.88 days on average, i.e. about 33½ days later in each successive year. For the period covered by the above star map, oppositions took place on May 4th 2006, June 5th 2007 and July 9th 2008. Around opposition, the planet is due South at local midnight in the Northern hemisphere (due North at local midnight in the Southern hemisphere).
The apparent diameter of the planet (i.e. its angular width as seen from the Earth, measured in arcseconds) at each successive opposition was 44".6 (on May 4th 2006) increasing to 45".7 (on June 5th 2007) and 47".2 (on July 9th 2008).
The apparent magnitude of the planet varied during the period shown in the star chart from -2.7 (at opposition) to -1.7 (at superior conjunction), making it considerably brighter than any of the stars shown (the brightest star shown is ruddy-coloured Antares, a red supergiant whose apparent magnitude ranges from +0.9 to +1.1 over a 5 year period. In 2007, the presence of brilliant white Jupiter near the orange-red Antares provided a good opportunity to observe their contrasting colours).
In April 2005 Jupiter passed the aphelion point of its orbit (i.e. its furthest point from the Sun; in this case 5.46 Astronomical Units or 816 million kms) and consequently was at its most poorly-placed orbital position when observed from the Earth. The situation has since improved and at opposition in September 2010 - when the planet was located in southern Pisces - it was seen at its brightest and best for its entire 11.8-year orbit. It's apparent equatorial diameter then measured 49".6 and shone at magnitude -2.9. Jupiter's perihelion (i.e. its closest point to the Sun, at 4.95 AU or 740 million kms) was reached six months later, in March 2011.
[Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]
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Observing Circumstances, 2007 to 2008
For observers at mid-Northern latitudes, Jupiter was seen low down in the sky over this period, as the planet traversed the Southernmost constellations of the zodiac. For 2007-8, when at meridian transit (due South), the planet appeared at its lowest angular elevation in the sky for some twelve years. Observing circumstances gradually improved from 2009, as the planet began to ascend the ecliptic once more, moving North-eastwards through Capricornus.
Conversely, during 2007-8, observers in mid-Southern latitudes saw Jupiter high up in the sky when it reached meridian transit (due North) providing optimal viewing conditions for telescopic observers.
A table showing Jupiter's transit altitudes as seen from various latitudes over a period of several years can be found on the current Jupiter page.
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Moon near Jupiter Dates,
September 2007 to December 2008
The Moon is easy to find, and on one or two days in each month, it passes Jupiter in the sky. Use the following table to see on which dates the Moon was in the vicinity of the planet:
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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 Jupiter when seen from some locations than from others. For this reason, the dates shown in the table should be used only for general guidance.
Credits
Copyright Martin J Powell February 2007
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