C/1995 O1 (Hale-Bopp)
Comet· orbits the Sun
C/1995 O1 (Hale-Bopp) was the 'Great Comet of 1997', bright enough to see with the naked eye for a record ~18 months. It has an unusually large nucleus and is on a long-period orbit that will not bring it back to the inner Solar System for roughly 2,400 years.
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Key facts
Perihelion
0.926 AU
Aphelion
361 AU
Orbital period
~2,400 years
Eccentricity
0.9949
Science
Physical
- Nucleus
- ≈ 40–80 km across (estimated) — exceptionally large for a comet
- Composition
- A dusty nucleus of water, carbon-monoxide and carbon-dioxide ices with silicate dust and organics; the comet was notably productive in gas and dust. No spacecraft has visited — figures are estimated from ground-based and Hubble Space Telescope observations.
Orbital
- Semi-major axis
- 181 AU
- From catalogued orbital elements (MPC)
- Eccentricity
- 0.9949
- From catalogued orbital elements (MPC)
- Inclination
- 89.73 °
- From catalogued orbital elements (MPC)
- Orbital period
- ~2,400 years · approximate — long-period orbit, shifts each passage
- From catalogued orbital elements (MPC)
- Perihelion
- 0.926 AU
- Computed from the orbital elements
- Aphelion
- 361 AU
- Computed from the orbital elements
- Mean orbital velocity
- 2.21 km/s
- Computed from the orbital elements
Activity
- Status
- Currently inactive (q = 0.926 AU, last perihelion April 1997)
- Becomes active within
- 5 AU of the Sun
Radiation & temperature
- Insolation
- 0.0000305 S⊕ · 1/32,813 of the sunlight Earth receives
- Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
Discovery & history
- Discovered
- July 23, 1995
- By
- Alan Hale and Thomas Bopp (independently)
- Method
- Visual discovery (telescopic)
- Name
- Named after its two independent discoverers.
Hale-Bopp was discovered on 23 July 1995, independently and within minutes, by Alan Hale in New Mexico and Thomas Bopp in Arizona. Unusually bright while still beyond Jupiter, it signalled a very large nucleus, and it went on to become the 'Great Comet of 1997' — visible to the naked eye for a record ~18 months.
Images
Images from open archives · credit shown per image