Above: The dark rippled dunes of Mars’ Proctor Crater likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago. The photo was taken by a HiRISE camera on board the Mars Reconnaissance Orbiter, currently in orbit around Mars. Photo: Nasa/ JPL/Caltech University of Arizona. Right: A new study led by a Yale University astronomer looked at a cluster of diverse galaxies, such as the bright one in the top middle of this 2006 Hubble Space Telescope photograph, and finds they have far more stars than initially thought. That means the universe may have three times more stars than astronomers previously figured. The bright part of the Hubble photo shows a cluster of galaxies 450 million light years away with the giant elliptical galaxy ESO 325-G004 looming large at the cluster’s centre.