Jupiter in 2002 to 2003


16 Apr 2003

Jupiter and its family of four "Galilean" moons...

Jupiter and family

Jupiter, with (left to right) Callisto, Io, Europa & Ganymede. 16 Apr 2003, 21:53BST (20:53UT)

The 4 moons orbit Jupiter in a single plane about the planet's equator, in increasing order of distance: Io, Europa, Ganymede and Callisto. In this picture Europa appears nearer to Jupiter than Io, but this is a line of sight effect. Europa has in fact just passed in front of Jupiter and its shadow still lies on the planet, as shown on the close up below.

To show the moons clearly a longish exposure is needed, which unfortunately means that Jupiter itself is over-exposed. In order to correct this I have manufactured a composite picture below, superimposing a decently exposed Jupiter amongst the satellites to give the sort of view that an approaching astronaut might see.

Minolta Dimage 7, 7mm @ f/3.5, afocal projection using 25mm eyepiece on 8.75inch f/7.3 Newtonian. 1/16s @ f/2.0, ISO400

Jupiter lies in the constellation of Cancer, near to the Beehive star cluster "Praesepe". Click here for a wide-angle view similar to what you would have seen in binoculars. In this 1 second exposure Europa is completely lost in the glare of the very over-exposed planet, but is necessary to show the much fainter star cluster.

Close-up of Jupiter, with the shadow of Europa lying on the face of Jupiter...

Jupiter, with Io and Europa plus its shadow; 16 Apr 2003, 21:16BST

Europa has just left transit (at 21:09BST), while its shadow lies towards the right of Jupiter, having arrived on the planet at 20:47. The sun shines from the left in this view and over the next two hours Europa moves further to the left (west) and its shadow crosses the face of Jupiter, as revealed in this time-lapse sequence. The moons themselves are rather faint compared to Jupiter itself so do not show up too well in this picture..

The two equatorial cloud belts are very prominent, with Jupiter's famous Great Red Spot adjacent to the upper (southern) belt. This is a great storm, bigger than the entire Earth, that has persisted on Jupiter for at least 300 years. It is Jupiter's largest storm, though is not always as red as the name suggests, and sometimes disappears completely leaving just a hollow in the adjacent cloud belt. Jupiter rotates in a little under 10 hours (giving rise to its noticeably elliptical shape) so within an hour the Spot has almost disappeared round the left hand side of the planet.

49.1mm @ f/3.5, afocal projection using 25mm eyepiece on 8.75inch f/7.3 Newtonian. 1/16s @ f/14, ISO400. Scale of 0.2 arc second (= approx. 800km) per pixel. 11 pictures stacked with Astrostack v2.1


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