47 Tucanae (47 Tuc or NGC 104) is the second
brightest globular cluster in the sky, with an angular size
roughly the same as that of the Sun or Moon, with an age
of 13 gigayears and a low metallicity.
It shows hints of more than one sub-population.
At least ten thousand individual stars can be discerned,
and it is presumed to total more than a million.
Its radius is about 60 ly and it has a very dense core.
It is an obvious candidate for the study of globular clusters and
is the subject of searches for a central black hole and for extra-solar planets.