The four Galilean satellites of Jupiter are readily visible through a pair of binoculars or a small telescope. A small telescope will also show at least Titan, the largest satellite of Saturn: a 20 cm telescope will show up to four other Saturnian satellites.
Eclipses of Saturn's satellites will be occurring during the few years. Through small telescope only those of Rhea and Titan are likely to be observable. Those of Rhea start in 2008 and continue to 2010. Eclipses of Titan occur during most of 2009.
Artificial Earth satellites can be seen moving silently across the sky almost any clear night. Information on when and where to look is available.Binoculars are sufficient to observe the 4 Galilean Satellites of Jupiter although a small telescope makes viewing easier. With a magnitude of about 5 they would be visible to the naked eye from a dark site if it were not for the glare of Jupiter. At regular intervals in its orbit round Jupiter, a satellite will be eclipsed in Jupiter's shadow, or occulted as it passes behind Jupiter or it will transit across the face of Jupiter. When any of these happen the satellite cannot be seen. Hence it is quite likely that at any time not all four will be visible.
October 2008, Jovian Satellite events visible from New Zealand.
November 2008, Jovian Satellite events visible from New Zealand.
December 2008, Jovian Satellite events visible from New Zealand.
January 2009: Jupiter is too close to the Sun for satellite events to be observed.
Eclipses of Saturn's satellite Rhea
are observable in January 2009.
Complete predictions of all events of the Jovian Satellites are available at the Institut de Mecanique Celeste at de Calcul Ephemerides.
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When at eastern or western elongation Titan's distance from the planet is about 5 times the diameter of the planet and its rings. For the past 15 years Titan has moved to be south of Saturn after eastern elongation, then to the west of Saturn and then to the north. In September 2009 the Earth will pass through Saturn's ring plane, after which Titan will pass to the south of Saturn following eastern elongation.
Saturns ring's are actually edge on to the Sun on August 10. For a few months either side of a series of eclipses of Titan will occur as it moves through Saturn's shadow. Normally the inclination of the satellite's orbit ensures it usually passes either to the south or the north of the planet's shadow when it is behind Saturn.
| Eastern Elongation | North of Saturn | Western Elongation | South of Saturn |
|---|---|---|---|
| 2008 | |||
| Nov 1 | Nov 5 | Nov 9 | Nov 13 |
| Nov 17 | Nov 21 | Nov 25 | Nov 29 |
| Dec 3 | Dec 7 | Dec 11 | Dec 15 |
| Dec 19 | Dec 23 | Dec 27 | Dec 31 |
| 2009 | |||
| Jan 4 | Jan 8 | Jan 12 | Jan 16 |
| Jan 20 | Jan 24 | Jan 28 | Feb 1 |
| Feb 5 | Feb 9 | Feb 13 | Feb 17 |
| Feb 21 | Feb 25 | Feb 28/ Mar 1 | Mar 5 |
| Mar 9 | Mar 12 | Feb 28/ Mar 16 | Mar 20 |
| Mar 24/25 | Mar 28 | Apr 1 | Apr 5 |
| Apr 9 | Apr 13 | Apr 17 | Apr 21 |
| Apr 25 | Apr 29 | May 3 | May 7 |
| May 11 | May 15 | May 19 | May 23 |
| May 27 | May 31 | Jun 4 | Jun 8 |
| Jun 12 | Jun 16 | Jun 20 | Jun 24 |
| Jun 28 | Jul 2 | Jul 6 | Jul 10 |
| Jul 14 | Jul 18 | Jul 22 | Jul 26 |
| Jul 30 | Aug 3 | Aug 7 | Aug 11 |
| Aug 15 | Aug 19 | Aug 23 | Aug 27 |
| Saturn is at conjunction with the Sun on September 18 so too close to it for observation. | |||
| Eastern Elongation | South of Saturn | Western Elongation | North of Saturn |
| Oct 18 | Oct 22 | Oct 26 | Oct 30 |
| Nov 3 | Nov 7 | Nov 11 | Nov 15 |
| Nov 19 | Nov 23 | Nov 27 | Dec 1 |
| Dec 5 | Dec 9 | Dec 13 | Dec 17 |
| Dec 21 | Dec 25 | Dec 29 | Jan 2 |
Titan, like most of the inner satellites of Saturn, orbits the planet in a plane close to the equator of Saturn and close to the plane of the rings. The equator and rings of Saturn are inclined at an angle of about 26° 45' to the plane of its orbit. This is just over 3° more than the inclination of the Earth's equator to its orbit.
For about half the time of its 29.5 year orbit of the Sun, the south pole of the planet is tilted towards the Sun, as at present. This is Saturn's equivalent to our summer in our southern hemisphere. At the same time the southern face of the ring system is lit by the Sun.
For the other half of the time the north pole is tilted towards the Sun, as in the southern hemisphere winter. The northern face of the ring system is also then lit. At the time of change over the equatorial rings become edge on to the Sun.
The rings become edge on to the Sun twice during Saturn's 29.5 year orbital period, following which the opposite face of the rings becomes lit. Also the Earth passes through the ring plane near the same time so that as seen from the from the Earth the rings appear edge on and for a short time difficult, if not impossible, to see. The Earth may in fact make either one or three passes through the ring plane over a period of a few months (never just two as in the end the face we can see changes).
Recently Saturn's rings have been closing as seen from the Earth. This will become very noticeable during 2008 so that by the end of the year they will look very narrow. After that they will in fact open slightly again during the first part of 2009 as the Earth swings round in its orbit, but the Earth will finally cross the ring plane on 2009 September 4 at 13:45 UT, (September 5, 1.45 am NZST, after Saturn has set in New Zealand). In 2009 there will be only 1 passage of the Earth through the ring plane.
The rings will be edge on to the Sun a few weeks earlier on August 10. After August 10 the northern face of the rings will be turned towards the Sun, while from Earth we will be seeing the southern, unlit face. This may make it difficult to see the rings during this time. They will in any case be nearly edge on from our point of view.
Eclipses of the inner satellites of Saturn only occur near the time the rings are edge on to the Sun. Of the somewhat brighter satellites, Mimas is closest to Saturn, its eclipses started in April 2006, Enceladus started in December 2006. Mimas and Enceladus need a moderate sized telescope to see at any time, the eclipses take place when the satellites appear close to Saturn making them even more difficult to see.
Tethys commenced eclipses 2007 August 27 and Dione 2007 December 26. Although these satellites are a little brighter and fairly easy to see in a 20 cm telescope, the eclipses also take place close to the disk of Saturn, so making them difficult targets.
Rhea will start being eclipsed mid 2008. Some of these eclipses will be further out from Saturn,also Rhea has a magnitude 9.8 making it a reasonably easy object, so eclipses may be detectable. Titan will be the easiest target, its eclipses start 2009 February 16. Titan has a magnitude 8.4 so is easily visible in a small telescope. Eclipses occur at 16 day's interval, each successive eclipse staring about an hour earlier. The first few again occur close to Saturn's disk, but a few in April and May particularly should be well placed for evening viewing from New Zealand.
Predictions for eclipses of Rhea and Titan will be placed on this site during 2008.
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Look up information on artificial Earth satellites visible from your own locality. Including Iridium flares (while they last), Mir, ISS, HST. A good site for satellite tracking predictions is Heavens-Above at heavens-above.com. Information on artificial satellites, comets, asteroids and more.
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