Frank Marchis - August 16, 2008

Dr. Frank Marchis of UC Berkeley will address the SJAA general meeting on August 16. The topic will be “Binary Asteroids”. Actually, binary is an understatement. Dr. Marchis and his colleagues at the Paris Observatory have been studying asteroids that are large enough to be considered minor planets, using the European Southern Observatory with adaptive optics. They found that the 187-mile-diameter planetoid 87 Sylvia has a satellite asteroid 11 miles across, orbiting about 860 miles away. And it has a 4.4 mile diameter satellite 450 miles out. They think Sylvia may have as many as 10 moonlets! A study of the orbital motions of these bodies suggests that Sylvia is likely a loose rubble pile with about 50% voids. It may be a reaggregation of fragments created in a shattering collision.