Looking for New Light

In many ways, astronomers are in the dark about asteroids. In the dark depths of the Kuiper Asteroid Belt beyond Neptune's orbit, and even in the nearby Main Belt between Jupiter and Mars, most asteroids are too small to reflect back enough sunlight to be seen by our telescopes. But as cosmic rays travel through our solar system, they may strike a glancing blow off the surface of an asteroid, producing gamma rays (short wavelength light waves). Researchers now report that they can use this gamma ray radiation to infer the number of small asteroids in different groups of small solar system bodies. However, they will have to wait to test their ideas until the new Gamma-ray Large Area Space Telescope (GLAST), launched last week by NASA, returns data.