A Centenary Survey of Orbits of Co-Orbitals of Jupiter

Abstract

Jupiter’s Trojan asteroids fulfill the prediction of Lagrange that orbits can be stable when a small body orbits in specific locations relative to its ‘parent’ planet and the Sun. The first such Trojan asteroid was discovered slightly over one hundred years ago, in 1906, and subsequently similar asteroids have been discovered associated with Mars and with Neptune. To date no Trojans have been discovered associated with Earth, but several horseshoe asteroids, co-orbital asteroids moving along a large range of the Earth’s orbit, have been found. Other planets also are not known to have Trojan-type asteroids associated with them. Since the number of detected Jupiter Trojans has increased dramatically in the last few years, we have conducted a numerical survey of their orbital motions to see whether any in fact move in horseshoe orbits. We find that none do, but we use the enlarged database of information about Trojans to summarize their properties as now known, and compare these to results of theory.