Sky Notes March 19 turn

y the central super-massive black hole and a family of roughly 15,000 globular clusters –
compared to the 157 globular clusters associated with the Milky Way.
The Virgo Cluster is the closest and best-studied great cluster of galaxies, at a distance of
approximately 50 to 70 million light years. It is the nucleus of the Local Supercluster of
galaxies, in whose outskirts we in the Milky Way and the Local Group are situated – and
gravitationally associated. 15 of the 109 Messier objects are Virgo Cluster galaxies.
In the first week or so of March the full array of Winter constellations are still well placed in
the evening, though not for much longer as we head into Spring. At 9 pm, Sirius is in the South
and above it and a bit to the left is Procyon. Both stars are bright as we see them and, in
astronomical terms, in “our neighbourhood”, Sirius being only 9 light years away and Procyon
11 light years distant. To the right of Procyon the imposing outline of the constellation Orion
has all of its primary stars much further away from us. Notably, Rigel, whilst it appears only
slightly brighter than Procyon, is in fact over 700 light years away, shining with a luminosity
around 80,000 times greater than our Sun. If Rigel were the same distance from us as Procyon,
it would be as bright as a first quarter Moon and casting shadows at night.
James Abbott
Picture: M87 - credit The Hubble Heritage Team