This Weekends Night Sky (13-14 Sept) Look out for Mercury this weekend, joining Mars and Saturn in our western evening sky. Mercury is the closest planet to the Sun, orbiting in just 88 day, so it always appears close to the Sun in our sky. This means we only ever see it low in the west just after the Sun sets, or low in the east just before the Sun rises. At the moment, Mercury is beginning its best evening appearance of the year and can be spotted low on the western horizon in the evening twilight. Towards the start of the evening, the Southern Cross (Crux/te Punga) lies on its side in the south west, with the two pointers, Alpha and Beta Centauri above. The cross appears to tip on its head and skim along the southern horizon as we move through the night. To the right of the pointers is Omega Centauri, a globular cluster containing around 10 million ancient stars. At around 150 light years across, it is the largest in our Milky Way galaxy. This is one of the few globular clusters visible to the naked eye, with an apparent magnitude of 3.9. With binoculars or even a modest telescope the cluster is a spectacular sight, covering nearly a full degree of the sky (twice the width of the full Moon). Slightly larger telescopes will easily pick out individual stars, particularly towards the edge of the cluster.
Posted on: Fri, 12 Sep 2014 08:55:11 +0000
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