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 Saturns 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, Titan in 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.
June 2008, Jovian Satellite events visible from New Zealand.
July 2008, Jovian Satellite events visible from New Zealand.
August 2008, Jovian Satellite events visible from New Zealand.
September 2008, Jovian Satellite events visible from New Zealand.
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. During 2008 when north or south of Saturn, Titan is much closer and by the end of the year will transit across the face of the planet when furthest north, and pass behind the planet, so being occulted, when furthest south.
Eclipses of Titan will not occur until February 2009. During 2008 the inclination of the satellite's orbit ensures it passes to the south of the shadow of the planet when it is behind Saturn, even when the satellite is occulted.
| Eastern Elongation | North of Saturn | Western Elongation | South of Saturn |
|---|---|---|---|
| 2007 | |||
| 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 |
| 2008 | |||
| Jan 3 | Jan 7 | Jan 11 | Jan 15 |
| Jan 19 | Jan 22 | Jan 26 | Jan 30 |
| Feb 3 | Feb 7 | Feb 11 | Feb 15 |
| Feb 19 | Feb 23 | Feb 27 | Mar 2 |
| Mar 6 | Mar 10 | Mar 14 | Mar 18 |
| Mar 22 | Mar 26 | Mar 30 | Apr 3 |
| Apr 7 | Apr 11 | Apr 15 | Apr 19 |
| Apr 23 | Apr 27 | May 1 | May 5 |
| May 9 | May 13 | May 17 | May 21 |
| May 25 | May 29 | Jun 2 | Jun 6 |
| Jun 10 | Jun 14 | Jun 18 | Jun 22 |
| Jun 26 | Jun 30 | Jul 4 | Jul 8 |
| Jul 12 | Jul 16 | Jul 20 | Jul 24 |
| Jul 28 | Aug 1 | Aug 5 | Aug 9 |
| Saturn is at conjunction with the Sun on September 4, so too close to it for observation. | |||
| Oct 16 | Oct 20 | Oct 24 | Oct 28 |
| 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 |
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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