Figure 15-12: Asteroid Collisions (a) This X-shaped profile of debris is suspected to result from the collision of two asteroids. The debris tails are made of dust and gravel, and this object (named P/2010 A2) is seen orbiting within the asteroid belt. (b) The asteroid Scheila unexpectedly doubled in brightness, which prompted a closer look at UV wavelengths. While UV images reveal dust plumes kicked up by a collision, they also indicate Scheila is not a comet (due to a lack of any water vapor emission lines in the plumes). Weeks after the collision’s plume was imaged, it faded from view. Within the white circle, images are combined at UV and visible wavelengths, and other than Scheila, the bright spots are stars.

(a: NASA/ESA/D. Jewitt [UCLA]; b: NASA)