Among the many spectacular objects in the southern skies are two magnificent naked-eye globular clusters, omega Centauri and 47 Tucanae. Both these common names imply that they are stars, yet both are clearly non stellar, even to the casual naked-eye observer. In binoculars or a small telescope they resolve into vast numbers of tiny stars.
These clusters are ancient cities of stars and are captives of the Milky Way. They were formed long before our Galaxy assumed its present shape, indeed these clusters have some of the oldest known stars.

This image is almost half a degree wide, the apparent diameter of the moon, yet the clusters stars spread far outside the frame. 47 Tuc is big and is about 15,000 light years distant, containing several million stars, as many as some minor galaxies. The crowded central region leads to occasional stellar encounters and it is in 47 Tuc that numerous, rapidly-spinning (milli-second) pulsars have been discovered by radio astronomers. Though the light of globular clusters is dominated by so-called 'red' giant stars, their colour is no redder than a domestic tungsten lamp, and the true colour of 47 Tuc appears in some of the related Images on this page.