Images of the asteroid Vesta taken by NASA's Hubble Space Telescope in May will help astronomers plan for the 2011 visit by the spacecraft Dawn, which is scheduled to launch on 7 July Astronomers used the newly released images to map out the southern hemisphere of the 530-kilometer diameter asteroid, which is dominated by a 456-kilometer diameter impact crater that formed billions of years ago. The images also reveal characteristics that could indicate volcanic activity, such as differences in brightness in the east and west that may reflect changes in composition. The images, taken by the telescope's Wide Field Planetary Camera 2, resolve features as small as 60-kilometers across. These new images as well as images taken in 2003 and 2004 of the dwarf planet Ceres, which Dawn will visit in 2015, are available at Hubble last imaged Vesta in 1994 and 1996.