From TaareWiki

Site: Jupiter Opposition and mutual events of Jovian satellites

Here is a celestial event that happens every year : the Opposition of Jupiter, which however carries with it some extra excitement this year.

But, first, what exactly is an opposition? An opposition of a solar system body happens when we see it in the sky positioned 180 degrees away from the Sun. The Sun sets and the celestial body rises, to set with sunrise. A position analogous to the full Moon.

Once in about a year, Jupiter (as do all outer planets) goes through an opposition – rising with sunset. Opposition is also the time when these outer planets become closest to the Earth for that cycle. Jupiter is certainly going to be the brightest object after the Moon, in the evening skies, around this opposition which is happening on the 14th of August this year.

The icing on the cake comes from the fact that this year also happens to be the time when it is equinox time on Jupiter. Unlike the Earth, equinox comes to Jupiter once in about 6 years. Coincidentally, equinox has also come to Saturn this year – a phenomenon that happens once in about 15 years. While equinox on Saturn has been dimming its rings, equinox on Jupiter brings the movements of its four Galilean satellites in a plane that is edge on as seen from the Earth.

This leads to many interesting mutual events related to the Galilean satellites of Jupiter – a merry dance where one satellite could move in front of another or the shadow of one satellite could fall on another, mysteriously blinking out that satellite for a moment. All such events related to the moons of Jupiter take place at the same time, as seen from anywhere on Earth. The year 2009 contains many such interesting mutual events of satellites of Jupiter, which can be seen through small telescopes. There is a special program of the International Year of Astronomy, which asks for worldwide observations – images and videos of these interesting events and Indian amateur astronomers should take full advantage of these events and capture them with equipment available to them and submit to this global project.

Useful Websites for Jovian satellite mutual events

http://www.astronomy2009.org/news/updates/293/

http://idialstars.com/ja14.htm

http://www.mikesalway.com.au/2009/08/06/jupiter-at-opposition-and-mutual-events-in-august-2009

http://www.imcce.fr/fr/presentation/equipes/GAP/travaux/phemu09/arlot-phenomena-sat-v3.pdf

http://www.bdl.fr/fr/observateur/campagnes_obs/phemu03/houjuillet2002.php

Retrieved from http://www.nehruplanetarium.org/taarewiki/pmwiki.php?n=Site.JupiterOppositionAndMutualEventsOfJovianSatellites
Page last modified on August 12, 2009, at 06:57 AM EST