Large and exceptionally active comet, which in March, 1997, made its closest approach to Earth since 2000 B.C., coming within 190 million kilometers or 118 million miles.

It has a diameter of approximately 40 kilometers or 25 miles and an extensive gas coma. Hale-Bopp has three tails: one consisting of dust particles, one of charged particles, and a third of sodium particles.

Comet Hale-Bopp was discovered in July, 1995, by two amateur U.S. astronomers, Alan Hale and Thomas Bopp.