The largest object in the Main Asteroid Belt between Mars and Jupiter is Ceres, an odd, water-rich proto-planet roughly the size of Texas (590 miles in diameter). Scientists have long puzzled about the origin of the bright white spot near the equator, which we recently learned is two bright spots. We'll soon know a lot more about it as NASA's Dawn spacecraft has nearly reached Ceres. It's already captured shots of the planet (above) and will soon go into a polar orbit at 13,500 km (8,300 miles) before descending to a survey altitude of 4,430 km (2,800 miles). Eventually, it'll drop as low as 1,480km (950 miles) to capture high resolution mapping data and 3D images of Ceres. Once the mission is over it'll remain the asteroid's orbiting buddy forever.