At approximately 1:00 AM Eastern Daylight Time this morning, the NASA Dawn space craft entered orbit around the size-M planetoid. For the next year, it will continue to orbit Vesta and reveal its secrets to us. Why did it never advance from protoplanet to a larger body? How has it been affected by the collision that removed a huge chunk at its southern pole?
Then Dawn will venture to another asteroid, the largest of them all, size-L Ceres - which has officially been named an official dwarf planet by the IAU.
Considering that the asteroids are likely future mining colonies for the human race, this is exciting. Although it is buried behind the story of the last Space Shuttle mission, this is the most important thing NASA is doing right now, and history will look back on this day as monumental.
Photo courtesy of NASA.
UPDATE: Here is the first photo from orbit of the 530 km (330 mile) diameter protoplanet:
UPDATE: Here are two more wonderful photos and a video from NASA. The first photo shows a close-up of the asteroid's southern polar region. The second is a great, full-frame detail shot. If you look to the left of the second photo, you'll see the three-crater formation that has been nicknamed the "snowman."