It was visible to the naked eye for a record 18 months, twice as long as the Great Comet of 1811, the previous record holder.
The previous record had been set by the Great Comet of 1811, which was visible to the naked eye for about 9 months. The comet continued to fade as it receded, but is still being tracked by astronomers.
Marsden, who had run the bureau since 1968, laughed, "Nobody sends telegrams anymore.
Comet Kohoutek in 1973 had been touted as a 'comet of the century' and turned out to be unspectacular. == Perihelion == Hale–Bopp became visible to the naked eye in May 1996, and although its rate of brightening slowed considerably during the latter half of that year, scientists were still cautiously optimistic that it would become very bright.
A precovery image taken at the Anglo-Australian Telescope in 1993 was found to show the then-unnoticed comet some 13 AU from the Sun, a distance at which most comets are essentially unobservable.
Comet Hale–Bopp (formally designated C/1995 O1) is a comet that was perhaps the most widely observed of the 20th century and one of the brightest seen for many decades. Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately on July 23, 1995, before it became visible to the naked eye.
Accordingly, Hale–Bopp was dubbed the great comet of 1997. == Discovery == The comet was discovered independently on July 23, 1995, by two observers, Alan Hale and Thomas Bopp, both in the United States. Hale had spent many hundreds of hours searching for comets without success, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale–Bopp just after midnight.
Comet Kohoutek in 1973 had been touted as a 'comet of the century' and turned out to be unspectacular. == Perihelion == Hale–Bopp became visible to the naked eye in May 1996, and although its rate of brightening slowed considerably during the latter half of that year, scientists were still cautiously optimistic that it would become very bright.
It was too closely aligned with the Sun to be observable during December 1996, but when it reappeared in January 1997 it was already bright enough to be seen by anyone who looked for it, even from large cities with light-polluted skies. The Internet was a growing phenomenon at the time, and numerous websites that tracked the comet's progress and provided daily images from around the world became extremely popular.
However, in April 1996 the comet passed within 0.77 AU of Jupiter, close enough for its orbit to be measurably affected by the planet's gravity.
It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp met and exceeded most predictions when it passed perihelion on April 1, 1997, reaching about magnitude –1.8.
Accordingly, Hale–Bopp was dubbed the great comet of 1997. == Discovery == The comet was discovered independently on July 23, 1995, by two observers, Alan Hale and Thomas Bopp, both in the United States. Hale had spent many hundreds of hours searching for comets without success, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale–Bopp just after midnight.
(Halley's Comet was more than 100 times fainter at the same distance from the Sun.) Analysis indicated later that its comet nucleus was 60±20 kilometres in diameter, approximately six times the size of Halley. Its great distance and surprising activity indicated that comet Hale–Bopp might become very bright when it reached perihelion in 1997.
It was too closely aligned with the Sun to be observable during December 1996, but when it reappeared in January 1997 it was already bright enough to be seen by anyone who looked for it, even from large cities with light-polluted skies. The Internet was a growing phenomenon at the time, and numerous websites that tracked the comet's progress and provided daily images from around the world became extremely popular.
Hale–Bopp had its closest approach to Earth on March 22, 1997, at a distance of 1.315 AU. As it passed perihelion on April 1, 1997, the comet developed into a spectacular sight.
The comet was much less impressive to southern hemisphere observers than it had been in the northern hemisphere, but southerners were able to see the comet gradually fade from view during the second half of 1997.
The last naked-eye observations were reported in December 1997, which meant that the comet had remained visible without aid for 569 days, or about 18 and a half months.
In October 2007, 10 years after the perihelion and at distance of 25.7 AU from Sun, the comet was still active as indicated by the detection of the CO-driven coma.
Herschel Space Observatory images taken in 2010 suggest comet Hale–Bopp is covered in a fresh frost layer.
Hale–Bopp was again detected in December 2010 when it was 30.7 AU away from the Sun, and on August 7, 2012, at a 33.2 AU distance from the Sun.
Hale–Bopp was again detected in December 2010 when it was 30.7 AU away from the Sun, and on August 7, 2012, at a 33.2 AU distance from the Sun.
Astronomers expect that the comet will remain observable with large telescopes until perhaps 2020, by which time it will be nearing 30th magnitude.
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