Sunday, January 07, 2007
Transit of Iapetus, 7-8 January
Eastern and Central Australia will be priveliged to see a rare transit of Iapetus across the rings of Saturn. Transits of Iapetus only occur every 7 years, with only four or five events during these favorable times. The down side is that Iapetus will be very faint (magnitude 11) and the rings rather bright, and you will need a serious telescope to see Iapetus at all, even then you may only see it when it crosses the Cassini division due to the rings brightness. Still, if you don't look you will never know.
Saturn rises at around 10:30 pm daylight saving time on Sunday 7 January in all Australian states. In Eastern states, Iapetus will enter the B ring at approximately 10:45 pm on Sunday, however, as Saturn is very close to the horizon, this will be impossible to see. At around 1:00 am daylight saving time in the eastern states, Iapetus will pass through the Cassini divison, between the A and B rings, and by about 2:20 am it will exit the A ring.
In Central states Iapetus is well into the B ring when Staurn rises, enters the Cassini division at around 12:30 am on the 8th and exits the A ring around 1:45 am on the 8th.
In Western Australia Iapetus is in the Cassini division around 11:00 pm on the 7th, being just above the horizon this will be hard to see. Iapetus exits the A ring a little after midnight.