Star Atlas
[1] The globular cluster Omega Centauri
seen in all its splendour in this image
by Pete Lawrence.
[2] Pete Lawrence captures the
hundreds of thousands of stars moving
about in the globular cluster M13 in the
constellation Hercules.
[3] The constellation Sagittarius
showing some of the brighter stars in
the shape of a teapot in the lower part
of the image, with the rich star clouds
above. ESA, NASA, Akira Fujii.
Spica high up. Virgo is a large constellation in the area between here and Leo,
and is very rich in galaxies. Arcturus is prominent in the northern part of the
sky, and one can appreciate how brilliant it really is. It is one of only three stars
above zero magnitude – the other two are Sirius and Canopus.The Great Globular Clusters
Also on view are Ophiuchus and Hercules. Find the globular cluster in
Hercules and compare it with Omega Centauri – it is obvious that Omega
Centauri is much the more populous of the two and is believed to have
a black hole at its centre. In fact, it is so massive that there have been
suspicions it was once an independent galaxy which was swept up by the
stars of Centaurus and this may well be so.
Two more constellations – Triangulum Australe, the Southern Triangle,
is one of the few constellations that looks like the object it is supposed
to represent. Its brightest star, Alpha, is of the second magnitude and
somewhat reddish.magnitude but are so distinctive they are impossible to overlook. Another
constellation, Libra, the Scales, lies between the constellations of Virgo
and Scorpius.
Zubeneschamali
One star in Libra, Beta Librae, with the extraordinary name of
Zubeneschamali, is said to be the only single naked eye star that is green
in colour! PM looked very hard at Beta Librae with the naked eye, binoculars
and telescopes, and once or twice has suspected a greenish tinge, but this
is possibly due to wishful thinking! The only obviously green stars are the
companions to red giants such as Antares and Alpha Herculis (Rasalgethi),
and here the greenness is almost certainly due to nothing more than
colour contrast.
Leo, the Lion
Turn now to the northern aspect. Leo is sitting in the west, with Arcturus and
3