The Asteroid Region is a region of the Solar System located between the orbits of Mars and Jupiter. It is made up of four main asteroids: BELT, CERES, EROS, VESTA, and Ida. BELT is the largest asteroid in the region, measuring about 2.2 AU in diameter. CERES is the second largest asteroid, measuring about 950 km in diameter. EROS is the third largest asteroid, measuring about 33 km in diameter. VESTA is the fourth largest asteroid, measuring about 525 km in diameter. Ida is the smallest asteroid in the region, measuring about 53 km in diameter.