SOLID AS A ROCK A planet about half the size of Neptune might be made of pure rock, making it larger than other known rocky planets (one illustrated).
TILTING AT WINDMILLS The planets of the Mu Arae system, illustrated, are now named for Cervantes characters, beating out those of science fiction writer Robert Heinlein.
European Southern Observatory
PRIME REAL ESTATE Hundreds of thousands of stars fill the Hercules Cluster, seen in this Hubble image. Such a cluster could be an ideal cradle for long-lived advanced civilizations, a new study suggests.