Posted: Sun, Oct 5, 2008, 7:19 PM ET (2319 GMT)
The Kuiper Belt of icy objects in the outer reaches of the solar system contained fewer medium-sized objects than first thought, according to a new survey. The Taiwanese-American Occultation Survey looked for occultations of distant stars by Kuiper Belt objects (KBOs), but in 200 hours of observations over a two-year period failed to detect a single occultation by a KBO. The lack of detections sets an upper limit on the number density of KBOs with sizes between 3 and 28 kilometers that is lower than what some theories suggest. Astronomers think that either objects of this size agglomerated into larger objects or were ground down by collisions into smaller objects.

Related Links:

•  New Scientist article
•  Harvard-Smithsonian CfA press release