Comet Hale-Bopp (C/1995 O1)

Discovered by:         Alan Hale and Thomas Bopp
Discovery date:        July 23, 1995
Also known as:        The Great Comet of 1997
Peak magnitude:      -1.0
Aphelion:                 370.8 AU (55.47 billion kilometres or 34.47 billion miles)
Perihelion:               0.914 AU (136.73 million kilometres or 84.17 million miles)
Semi-major axis:      186 AU (27.83 billion kilometres or 17.51 billion miles)
Eccentricity:            0.995086
Orbital period:          2533 years
Inclination:               89.4 degrees

Last perihelion:        April 1, 1997
Next perihelion:       4385 (estimate)
 

Comet Hale-Bopp photographed on April 4, 1997 (E. Kolmhofer, H. Raab; Johannes-Kepler-Observatory, Linz, Austria)

Comet Hale–Bopp is also known as the Great Comet of 1997.

Discovered on July 23, 1995 by amateur astronomers Alan Hale and Thomas Bopp when located 7.2 AU from the Sun. At this great distance it was between the orbits of Jupiter and Saturn.

Apparent magnitude at discovery was +10.5.

Holds the record for farthest comet from the Sun discovered by amateurs.

Images obtained at discovery showed a coma which is unusual for comets so far from the Sun.

Although comets are notoriously unpredictable, Hale-Bopp attained or even exceeded initial expectations.

It was visible to the naked eye for a record 18 months - twice as long as the previous record holder, the Great Comet of 1811.

The comet was brighter than magnitude 0.0 for eight weeks, which is longer than any other recorded comet.

Closest approach to Earth occurred on March 22, 1997 at a distance of 1.315 AU (196.7 million kilometres or 122.2 million miles). The comet reached perihelion a few days later on April 1, 1997.

After passing perihelion Hale-Bopp was a spectacular sight in the evening sky, especially for Northern Hemisphere observers.

At peak magnitude, it was brighter than all nighttime stars except for Sirius and is probably the most viewed comet in recorded history.

Its dust tail stretched 45 degrees.

The nucleus of Hale Bopp is large. It's estimated to be at least 40 kilometres (25 miles) in diameter, approx. 6 times the size of comet Halley.

As a consequence of orbital perturbations, the comet is predicted to next return around 4385.