Comet Hyakutake

C/1996 B2 (Hyakutake)

Comet Hyakutake in 1996
Discovery
Discovered by	Yuji Hyakutake
Discovery date	31 January 1996[1]
Designations
Pronunciation	Japanese pronunciation: [çakɯ̥take]
Alternative designations	Great Comet of 1996
Orbital characteristics[2][3]
Epoch 2450400.5
Aphelion	~1320 AU (inbound)[3][a] ~3500 AU (outbound)
Perihelion	0.2301987 AU
Semi-major axis	1700 AU (outbound)[3][a]
Eccentricity	0.9998946
Orbital period (sidereal)	~17,000 yr (inbound)[3][a] ~72,000 (outbound)
Inclination	124.92246°
Longitude of ascending node	188.05766°
Argument of perihelion	130.17218°
Physical characteristics
Dimensions	4.2 km (2.6 mi)[4]
Sidereal rotation period	6 hours

Comet Hyakutake (formally designated C/1996 B2 (Hyakutake)) is a comet discovered on 31 January 1996.^[1] It was dubbed the Great Comet of 1996; its passage to within 0.1 AU (15 Gm) of the Earth on 25 March was one of the closest cometary approaches of the previous 200 years. Reaching an apparent visual magnitude of zero and spanning nearly 80°, Hyakutake appeared very bright in the night sky and was widely seen around the world. The comet temporarily upstaged the much anticipated Comet Hale–Bopp, which was approaching the inner Solar System at the time.

Hyakutake is a long-period comet that passed perihelion on 1 May 1996. Before its most recent passage through the Solar System, its orbital period was about 17,000 years,^[3][5] but the gravitational perturbation of the giant planets has increased this period to 70,000 years.^[3][5] This is the first comet to have an X-ray emission detected, which is most likely the result of ionised solar wind particles interacting with neutral atoms in the coma of the comet. The Ulysses spacecraft fortuitously crossed the comet's tail at a distance of more than 500 million km (3.3 AU; 310 million mi) from the nucleus, showing that Hyakutake had the longest tail known for a comet.