A guide to what's up in the sky for Southern Australia

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The Pleiades star cluster (31st Dec 2024)

The Pleiades star cluster (The Seven Sisters) Distance: 435 Light Years

The rich blue clouds and delicate tendrils of reflection nebulosity surrounding the brightest members have their origin in an unrelated molecular cloud and do not represent the ancestral cloud which gave rise to the Pleiades.

The proximity of this great cluster allows a close-up view of a young open cluster and the fascinating interplay of a moving star cluster with the interstellar medium.

Although the core of the cluster contains some 100 bright stars, mostly hot A and B types, the total number of stars may be closer to 400 as many lower mass members have been identified recently. The central core radius of the cluster is only about 4.5 light-years, but the remote outer regions of the
cluster may extend out as far as 52 light years from the centre. The brighter members of the cluster are blue stars with surface temperatures of about 20,000 degrees.