Go west young astronomer to see the Moon hide Jupiter and its moons on 18 February 2013
Jupiter and its four Galilean moons on the evening of 30 January 2013. Europa is on the left, Io is too close to the planet to see, then Ganymede and, finally, on the right Callisto.Picture Nick Lomb
Currently, the bright planet Jupiter is prominent each evening in the northern sky. On the night of Monday 18 February, as seen from Sydney, the first quarter Moon will be gliding past Jupiter around midnight. The sight will be worth staying up for, with the separation between edge of the Moon and the planet only about three minutes of arc – this angular distance is equivalent to only about a tenth of the Moon’s width.
The dark edge of the Moon about to start covering Jupiter and its four Galilean moons at 11:25 pm on 18 February 2013. Diagram Nick Lomb using Stellarium software
However good the sight will be from Sydney, it will be better from places such as Melbourne, Hobart, Adelaide and Perth where onlookers will see the Moon actually cover or occult Jupiter. In those places people with a small telescope will not only see the planet itself disappear, but over a period of about 20 minutes see its four Galilean moons covered one at a time. And a little later, over a period of about ten minutes, Jupiter and its four moons will reappear at the bright edge of the Moon.
The end of the occultation with Jupiter and its four Galilean moons reappearing from behind the Moon as seen from Melbourne at 12:17 am on 19 February 2013. Diagram Nick Lomb using Stellarium software
Times for the disappearance and reappearance of Jupiter from a few state capitals on the evening of Monday 18 February and the morning of Tuesday 19 February 2013:
Adelaide….11:00 pm CDT……..11:37 pm CDT
Hobart…….11:22 pm AEDT……12:13 am AEST
Melbourne..11:33 pm AEST…….12:10 am AEST
Perth………..7:40 pm WST…. …..8:46 pm WST
Times for more places are available from the website of The International Occultation Timing Association.
In the past astronomers used occultations of stars by the Moon to refine the path of the Moon and its shape. Such observations were regularly made at Sydney Observatory with its astronomers on occasion even taking over the main telescope during public viewings for a few minutes – for visitors this was often a highlight of their tour. Some advanced amateur astronomers continue to make such observations.
Whether you observe the Moon narrowly miss Jupiter from Sydney or take the opportunity to go west to see the occultation, you should see a great sight and have the opportunity to take some impressive photos. All that is needed is a clear sky!