Imagine that once the Sun sets, rather than a dark sky sprinkled with a few thousand dim stars, we had a sky blazing with ten thousand or so stars blazing brighter than Venus. How different would astronomy, mythology, everyday life be?
Planets orbiting stars in the NGC 3603 Young Cluster would experience just such a sky. Just three light years across, this compact cluster squeezes in ten thousand stars. In contrast, a similar volume in our neighbourhood centred on our Sun would contain only one star. Most stars in this cluster are of similar size to the Sun, but there are giants too, including some blue-white supergiants which are among the biggest stars ever discovered. These will soon detonate as spectacular supernovae.
The nebula NGC 3603 is some 20 000 light years from us in the Carina Spiral Arm and is an unusually compact yet massive stellar nursery. The stars in the central cluster were born together in one furious burst of creation about a million years ago. Atypically most of the nebula’s material has gone into making stars. Usually only about ten percent of of a star-forming region’s matter goes into the stars it makes, the rest being dispersed by the nascent stars’ radiation and stellar winds. Afterwards the new stars drift apart as there is nothing to keep them together (the Hyades in Taurus would be an example of this happening). However in the NGC 3603 Young Cluster the stars contain so much of the original matter that their gravity may keep them together throughout their lives.
Sadly these stars’ youth and short projected lifetimes mean that there are no eyes on their planets to gaze up in wonder at their beauty. Here on our little world, circling our solitary star we will have to use our imaginations to appreciate this magnificent spectacle.