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Centaur
2011-Aug-24, 01:37 AM
That brilliant beacon in the late evening eastern sky, giant Jupiter, has been growing brighter and rising about four minutes earlier each night. It will reach opposition to the Sun by celestial longitude in American time zones on 2011 OCT 28. At that time it’ll be rising around sunset, transiting the local meridian near local midnight, and setting about sunrise. Beginning 2011 AUG 30 it will exhibit apparent retrograde motion on star charts.

All dates given here are for the US central time zone. Jupiter reached the perihelion (closest to Sun) of its nearly 12-year orbital cycle this past March and will be only 3.9698 AU from Earth on OCT 28 at an angular diameter of 49.6 arcseconds and magnitude -2.9. That’s just slightly further and virtually the same brilliance as last year’s opposition, which is about as bright as it ever gets. That’s significantly brighter than the brightest fixed star Sirius, but noticeably less bright than Venus.

Jupiter’s opposition declination has been improving for northern hemisphere observers since the low of 2008. This year it is roughly halfway between the celestial equator and its maximum possible northern declination. So its transit altitudes for observers north of the tropics will be better than in recent years, but not quite as good as the next few years.

As viewed from Earth the tilt of Jupiter’s equatorial plane at opposition will appear to be +3.3 which is near the maximum. The orbital planes of the four Galilean satellites lay close to that plane and mutual events (transits, occultations, eclipses) not involving Jupiter will not occur during the current apparition. In fact for now Callisto will always appear to pass north or south of Jupiter during conjunctions. Of course the events involving Jupiter and the inner three Galilean satellites and their shadows will still happen during every one of their orbital periods.

Jupiter will resume apparent direct motion on DEC 25 and reach eastern quadrature (90 from Sun) on 2012 JAN 22 at which time it will be setting around local midnight. Conjunction behind the Sun will be achieved on MAY 13.

Venus will appear to pass 3.0 north of Jupiter on MAR 13. Except for that event, during this apparition Jupiter will not be in conjunction with any other planets or first magnitude stars.

The Moon will appear to pass a few degrees north of Jupiter on 2011 AUG 20, SEP 16, OCT 13, NOV 09, DEC 06, 2012 JAN 02, JAN 30, FEB 27, MAR 25 & APR 22.

I’ve created several graphics related to Jupiter and its current apparition. That includes long-term graphs for brightness and declination. I also preview shadow transits when appropriate. The graphics can be seen by going to www.curtrenz.com/jupiter

Photos and descriptions of Jupiter and its satellites during the current apparition would be welcome additions to this thread.

Middenrat
2011-Sep-14, 02:24 AM
Revisiting this thread as the lunar conjunction of 16 Sep approaches, what a great write-up, thanks Centaur.