Tonight's Sky: September 2013.
Backyard stargazers get a monthly guide to the northern hemisphere's skywatching events with "Tonight's Sky." Look for dense star cluster M2, home to 150,000 stars.
"Tonight's Sky" is produced by the Space Telescope Science Institute at HubbleSite.org, online home of the Hubble Space Telescope. This is a recurring show, and you can find more episodes -- and other astronomy videos.