Spectacular and sparkling, but what is it?

Globular clusters are among the most spectacular of objects in the entire night sky. Compact balls of hundreds of thousands of stars, well over a hundred orbit our galaxy at various distances. When viewed by Hubble, the result is nothing less than jaw-dropping:

[Click to embiggen, and please do; I had to crop the image to get it to fit and the full-size version is even more spectacular!]

This view of Terzan 5, as it’s called, is gorgeous! The thing is… Terzan 5 may not really be a globular cluster. Sure, it’s a cluster, and it’s globular, but it may not be what we usually think of as a globular cluster.

When I read the press release for the picture, the name Terzan 5 looked familiar. So I searched my blog, and found I’ve written about this object before. That post was about a ground-based Very Large Telescope picture of the cluster, seen here. The picture looks odd because Terzan 5 lies in a very crowded region of the Milky Way, lousy with dust. That interstellar junk tends to scatter away blue light, ...

Full story at http://blogs.discovermagazine.com/badastronomy/2011/05/23/spectacular-and-sparkling-but-what-is-it/