Omega Centauri, from the Spitzer Space Telescope, that is. From the JPL/Caltech press release:
It is the biggest and brightest of the 150 or so similar objects, called globular clusters, that orbit around the outside of our Milky Way galaxy. Stargazers at southern latitudes can spot the stellar gem with the naked eye in the constellation Centaurus.
Globular clusters are some of the oldest objects in our universe. Their stars are over 12 billion years old, and, in most cases, formed all at once when the universe was just a toddler. Omega Centauri is unusual in that its stars are of different ages and possess varying levels of metals, or elements heavier than boron.
This cluster may well be an omega, an ending of sorts. These different ages of component stars might suggest it is a remnant of a dwarf galaxy once devoured by the gravitational forces of the Milky Way.