Hubble Sees Messier 70: Tight and Bright In this image, the
NASA/ESA Hubble Space Telescope has captured the brilliance of
the compact center of Messier 70, a globular cluster. Quarters
are always tight in globular clusters, where the mutual hold of
gravity binds together hundreds of thousands of stars in a small
region of space. Having this many shining stars piled on top of
one another from our perspective makes globular clusters a
popular target for amateur skywatchers and scientists alike.
Messier 70 offers a special case because it has undergone what
is known as a core collapse. In these clusters, even more stars
squeeze into the object's core than on average, such that the
brightness of the cluster increases steadily towards its center.
The legions of stars in a globular cluster orbit about a shared
center of gravity. Some stars maintain relatively circular
orbits, while others loop out into the cluster's fringes. As the
stars interact with each other over time, lighter stars tend to
pick up speed and m