The Last Return

Abstract

Halley’s Comet is neither the brightest of comets nor the most frequently seen, but it is the only bright comet that returns within a relatively short period of time. Most comets have retained their original orbital periods lasting many thousands of years; thus each of the bright ones has graced the inner solar system with its spectacular tail no more than once in recorded history. The orbits of a few, however, have been affected by one or another of the four giant planets. Jupiter, Saturn, Uranus, and Neptune each have sufficient gravitational pull to perturb the orbit of a comet into a period of only a few years or decades. This brings about more frequent periodic visits to the region of the inner solar system near the Sun and the Earth. Most comets of either orbital group are faint—too faint to be visible to the naked eye, much less spectacular, at any time. Of all comets, Halley’s alone has been seen and recorded as a spectacular object more than once.