Small Worlds Ceres and Vesta . ... Credit Copyright: NASA , ESA , L.McFadden, J.Y.Li ( UMCP ), M.Mutchler, Z.Levay ( STScI ), P.Thomas ( Cornell ), . J.Parker, E.Young ( SwRI ), C.Russell, B.Schmidt ( UCLA ) Explanation: Ceres and Vesta are, respectively, only around 950 kilometers and 530 kilometers in diameter - about the size of Texas and Arizona. ... These remarkably detailed Hubble Space Telescope images show brightness and color variations across the surface of the two small worlds. ...