A Good Question!

A couple of days ago, the folks at the Hubble Space Telescope Science Institute delivered up a lovely image of the globular cluster M13 (in Hercules, which isn’t visible right now, but is a nice late spring evening sight and is even better in the mid-summer months.  (Yes, I know the press release material on the STScI website says it’s a nice winter sight and that would be true in the southern hemisphere (where winter is about to start). For the folks in the northern hemisphere, Hercules is a spring and summer constellation.)

This particular view is of the central 20 light-years of the cluster, and shows just a fraction of the more than 150,000 stars that are packed into M13.

Globulars are interesting beasts. They typically have some of the oldest stars in the universe — some dating back to well before the formation of the Milky Way Galaxy. Their stars are born in great bunches during intense star-formation periods that mark epochs of galaxy formation. Astronomers study them quite intensely because these globs of stars are likely the key to understanding what conditions were like back when the Milky Way was being assembled from smaller dwarf galaxies. The collisions and interactions likely spurred the huge bursts of starbirth that formed globular clusters.