4 VESTA

4 Vesta is one of the largest objects in the asteroid belt, with a mean diameter of 525 kilometers (326 mi). Vesta is thought to be the second-largest asteroid, both by mass and by volume, after the dwarf planet Ceres.
NASA's Dawn spacecraft entered orbit around Vesta on 16 July 2011 for a one-year exploration and left the orbit of Vesta on 5 September 2012 en route to its final destination, Ceres. Researchers continue to examine data collected by Dawn for additional insights into the formation and history of Vesta. It takes 3.6 years to orbit Earth.