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Tuesday, May 21, 2013


Occultation (and close approach) of Spica Wednesday May 22, 2013

The evening sky facing north-east in Darwin on May 22 at 19:00 pm ACST showing the waxing Moon just about to cover Spica (alpha Virginis). (similar views will be seen from other locations north of Bundaberg at a similar local time eg 20:05 AEST Cairns). The inset shows a telescopic view of the Moon at 19:00 ACST, with Spica about to go behind the Moon.

The waxing Moon passes in front of the bright star Spica in the constellation of Virgo on the evening of May 22. Spica is a bright white star visible to the unaided eye (magnitude 1).

The occultation will only be seen from north-eastern Australia, anywhere north of a line running just below Darwin to Bundaderg.

Every where else will see Spica dramatically close to the Moon, it is well worth watching even if you don't have an occultation. In Adelaide and Alice Springs the Moon is less than half a lunar diameter from Spica, and in Brisbane it floats just above the surface, almost grazing. Nambour sees a graze starting at 20:01 AEST.

From Darwin the star disappears behind the dark limb of the Moon at 19:17 ACST, and reapppears at 19:43 ACST. From Rockhampton the star disappears behind the dark limb of the Moon at 20:35 AEST, and reapppears at 21:11 AEST. From Cairns and Townsville the star disappears behind the dark limb of the Moon at 20:05 AEST, and reapppears at 21:07 AEST.

With the Moon nearly Full, this event is really best seen with binoculars or a small telescope (especially for the reappearance of the star on the bright limb of the Moon). If you have a tripod or other stand for your binoculars, it will be much easier to observe. Otherwise try and stabilise your binoculars on the back of a chair, or a car roof or something similarly solid. Set up about half an hour before the occultation to watch the star dissapear (so you are not mucking around with equiment at the last moment).

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