Globular clusters are so cool. They are really old… globular clusters contain the oldest of stars, and date back to the beginning of our Milky Way, and may be a good place to look for alien civilizations! And they are dense- hosting a million stars in a volume only 100 light years across. It is this fact that interests astronomers using pulsars as a way to probe the inner structure and origin of these ancient relics.
Globular cluster Terzan 5 is home to 37 known pulsars! Many of these are rapidly spinning pulsars known as millisecond pulsars. Astronomers have bean measuring Terzan 5’s uneven tug of gravity on these pulsars to determine the internal structure of the cluster.