Travelers In The Night

Humans know of approximately half million main belt asteroids orbiting the Sun between Mars and Jupiter. We have also found approximately 11,000 Earth approaching asteroids. Members of these two groups can be recognized by briefly observing their motion since their paths about the Sun are very different. Jupiter Trojans, on the other hand, occupy a point either 60 degrees in front or behind Jupiter as it moves about the Sun. Their orbit around the Sun takes about 5 and a half years so short pieces of one of their orbits can mimic the path of an Earth approaching object. When Jupiter Trojans are opposite to the Sun, their little full moon faces are pointing towards Earth. When they are in this position in the sky we have to sort through a number of them so we can separate them from real near Earth objects.