Comet Hyakutake
The Great Comet of 1996, which swept within 15 million km of Earth with a tail stretching across the sky.
Key facts
- Designation
- C/1996 B2 (Hyakutake)
- Type
- Long-period comet
- Orbital period
- about 70,000 years now; about 17,000 years before this pass
- Closest to the Sun
- 0.23 AU (about 34 million km)
- Farthest from the Sun
- a few thousand AU
- Tilt of orbit
- about 125° (retrograde)
- Nucleus
- about 4 km across
- Discovered
- by Yuji Hyakutake in Japan on 30 January 1996
- Returns
- passed closest to Earth on 25 March 1996 and closest to the Sun on 1 May 1996
Orbit
Hyakutake fell in from the far reaches of the Solar System. On 25 March 1996 it passed about 15 million km from Earth, roughly 40 times the distance of the Moon, and moved visibly against the stars in an hour. The planets' gravity lengthened its orbit, so it will not return for tens of thousands of years.
Size and nature
The nucleus is only about 4 km across, so its brilliance came from its nearness. At its best its gas tail stretched over a quarter of the sky from dark places. It was the first comet found to give off X-rays, produced as the solar wind struck its gas. Years later, scientists realised the Ulysses spacecraft had crossed its tail in May 1996 about 570 million km from the head, making it the longest comet tail known.
History
Yuji Hyakutake, a Japanese amateur astronomer, found it with large binoculars in January 1996, only weeks after finding another comet. It became the Great Comet of 1996, just a year before Hale–Bopp, and the two together made the mid-1990s a remarkable time for comet watching.
Meteor showers and missions
Hyakutake's orbit does not meet Earth's in a way that produces a shower. No spacecraft was sent to it, but telescopes found ethane and methane in a comet for the first time.
Key dates
| Date | What happened |
|---|---|
| 30 January 1996 | Yuji Hyakutake discovered the Great Comet of 1996. |
| 25 March 1996 | Comet Hyakutake passed about 15 million km from Earth. |
Did you know?
Hyakutake's tail was the longest yet measured for any comet.
Its pass was one of the closest of any comet to Earth in 200 years.
Comet X-rays, first found here, are now known to be common.