Comet Hale–Bopp
The Great Comet of 1997, visible to the naked eye for a record 18 months, with a giant nucleus about 60 km wide.
Key facts
- Designation
- C/1995 O1 (Hale–Bopp)
- Type
- Long-period comet
- Orbital period
- about 2,400 years now; about 4,200 years before it passed Jupiter in 1996
- Closest to the Sun
- 0.91 AU (about 137 million km)
- Farthest from the Sun
- about 360 AU
- Tilt of orbit
- about 89°
- Nucleus
- about 60 km across (estimates range from about 40 to 80 km)
- Discovered
- by Alan Hale in New Mexico and Thomas Bopp in Arizona on 23 July 1995
- Returns
- passed perihelion on 1 April 1997
Orbit
Hale–Bopp's orbit is tilted almost at right angles to the planets. On its way in, in April 1996, it passed Jupiter, which shortened its period from about 4,200 to about 2,400 years. It never came especially close to Earth; its brightness came from its sheer size.
Size and nature
The nucleus is one of the largest seen in any comet that has come near the Sun, perhaps 60 km across, and it threw off enormous amounts of gas and dust. It had two clearly separate tails, a curved, yellowish dust tail and a straight blue gas tail, and a third, faint tail of sodium atoms was discovered by astronomers in the Canary Islands.
History
Alan Hale and Thomas Bopp found it on the same night in July 1995, Hale from his driveway and Bopp while observing with friends in the desert. It was then beyond Jupiter's orbit, farther out than any comet found by amateurs before, and as bright as a comet usually is much closer to the Sun, which hinted at its size. It became visible to the naked eye in mid-1996 and stayed visible until late 1997, about 18 months. Millions of people saw it, even from bright cities.
Meteor showers and missions
Hale–Bopp has no known meteor shower: its orbit does not come near Earth's. No spacecraft visited it, but the SOHO solar observatory and ground telescopes studied it closely.
Key dates
| Date | What happened |
|---|---|
| 23 July 1995 | Alan Hale and Thomas Bopp discovered the comet that became the Great Comet of 1997. |
| 1 April 1997 | Comet Hale–Bopp passed closest to the Sun. |
Did you know?
Hale–Bopp was the most widely seen comet of the twentieth century.
Its previous visit, about 4,200 years ago, was in the Bronze Age.
It produced so much dust that, at its peak, it lost hundreds of tonnes every second.