Final answer:
The statement is true; NASA's Dawn mission studied Vesta and then went on to study the dwarf planet Ceres, providing valuable data on these large main belt asteroids.
Step-by-step explanation:
The statement that the Dawn mission finished studying the asteroid Vesta and is now studying the dwarf planet Ceres is true. The Dawn spacecraft launched by NASA was indeed the most ambitious asteroid mission as it visited both Vesta and Ceres. With Vesta measuring approximately 500 kilometers in diameter and Ceres approximately 1000 kilometers, they are considered the two largest main belt asteroids, with Ceres also classified as a dwarf planet.
Vesta is notable for being a differentiated asteroid with a basaltic surface and having bright surface features visible even without a telescope. After Dawn's visit, Ceres became known for its white feature in the Occator crater among other composition differences highlighted in color-enhanced images. The Dawn mission has provided valuable insights into these celestial bodies, indicating they both have ancient, heavily cratered surfaces.