The four Galilean satellites of Jupiter are readily visible through a pair of binoculars or a small telescope. The inclination of Jupiter's equator to its orbit is small, just over 3°. Since the orbits of the Galilean satellites are very close to the plane of the equator they are frequently eclipsed in Jupiter's shadow. The inner three are eclipsed every orbit, the outermost, Callisto, misses the shadow when one of Jupiters poles are tilted towards the Sun.
Artificial Earth satellites can be seen moving silently across the sky almost any clear night. Information on when and where to look is available.
Events of the Galilean Satellites of Jupiter Visible from New Zealand
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.
January 2012 December 2011 November 2011 October 2011
September 2011 August 2011 July 2011 June 2011
May 2011 April 2011 - no events March 2011 February 2011
Complete predictions of all events of the Jovian Satellites are available at the Institut de Mecanique Celeste at de Calcul Ephemerides.
Saturn's rings and larger satellitesDates of elongation of Titan for 2010
The equator and rings of Saturn are inclined, at an angle of about 26° 45' to the plane of its orbit, far more than Jupiter's inclination. Saturn's inclination is just over 3° more than is the Earth's to its orbit.
For about half the time of its 29.5 year orbit of the Sun, the north pole of the planet is tilted towards the Sun. It most recently started to tilt towards the Sun after the ring plane passed through the Sun in August 2009. Also the northern face of the ring system is lit now by the Sun. The next reversal does not take place until May 2025.
As seen from the Earth the north face of the rings has been in view since September 2009, when the Earth passed through the ring plane, and will remain in view until March 2025.
The rings become edge on to the Sun twice during Saturn's 29.5 year orbital period. After being edge on the previously unlit face begins to be sunlit. Near to the time the rings are edge on to the Sun, the Earth also passes through the ring plane 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). Three passes occur when the faster moving earth moves forward, then back and then forward again through the ring plane. The next triple pass will be in 2038 and 2039.
Following on the Earth moving through the ring plane, the rings will gradually become more exposed to view over the next few years, appearing very narrow at first. Over the course of a year the rings will appear to open and then close a little as the Earth swings from side to side in its orbit. The rings will reach their greatest exposure in late 2017.
Eclipses of the inner moons of Saturn only occur near the time the rings are edge on to the Sun. Eclipses of the brightest moon, Titan, occurred during 2009, with the last eclipse of the series taking place on 1 January 2010 with a disappearance at 21:26 UT and reappearance at 23:51 UT. (These are in the middle of the day in New Zealand.)
Eclipses of the next brightest satellite, Rhea which orbits Saturn more closely than Titan, started in mid 2008 and continue until August 2010. While eclipses of satellites still closer to Saturn continue for longer, the events occur so close to Saturn that they are only visible in relatively large telescopes.
Titan, Saturn's largest satelliteTitan, with a magnitude of about 8.5, can be seen through a small telescope. The satellite takes almost 16 days to orbit Saturn. The table shows the dates of its extreme positions with respect to Saturn for 2011. Close to conjunction with the Sun, it is not possible to view planet, data is omitted for a few weeks either side of conjunction on October 13.
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 2011 when north or south of Saturn, Titan will just over 1 diameter of Saturn from the planet at the beginning of the year. By the end of 2011, this distance will have increased to about 2 diameters.
The table below shows the dates at which Titan is at eastern or western elongation and when it is north or south of the planet.
Because they are mostly in relatively low orbits, the visibility and times when artificial satellites are visible depends on your location. A good site for satellite tracking predictions is Heavens-Above at heavens-above.com. Information on artificial Earth satellites visible from your own locality can be obtained. This includes Iridium flares, ISS, HST. The site has information on artificial satellites, comets, asteroids and more.