A US-Israel astronomy team has discovered a very small heavenly body – less than half a mile across – in the Kuiper belt at the far reaches of our solar system.
The researchers, who included five Israelis from the Hebrew University of Jerusalem, Tel Aviv University and the Weizmann Institute of Science, found the object beyond Neptune’s orbit, according to an article published in the December 17 issue of the journal Nature.
Previously, only a single object has been found in the Kuiper belt, located around 30 to 60 astronomical units (au) from the Sun (each au is equivalent to about 93 million miles). The belt contains ice-and-rock bodies that are remnants of the primordial solar system.
The researchers, headed by Hilke Schlichting of the California Institute of Technology, suggest that because there are few such bodies in the belt, they apparently “are being lost to collisional erosion.”
Kuiper belt objects cannot be seen with a telescope, but they can be detected when they pass in front of a distant star, a phenomenon called occultation. The team searched for occultations in four-and-a-half years of data from the Hubble Space Telescope’s fine guidance sensors, which control the telescope’s movement by observing guide stars.