Gaspra's very irregular shape suggests the asteroid came from a larger body by what was nearly a catastrophic collision. The large concavity on the lower right limb is about 6 kilometers (3.7 miles) across. The prominent crater on the terminator (center left) is about 1.5 kilometers (1 mile) across. A striking feature of Gaspra's surface is the abundance of small craters. More than 600 craters 100-500 meters (330-1650 feet) in diameter are visible in this image.