View source for Comet Hale–Bopp

{{short description|Great Comet of 1997}}
{{Redirect|Hale Bopp|the composition by Graham Waterhouse|Celtic Voices and Hale Bopp}}
{{featured article}}
{{Use British English|date=March 2018}}
{{Use mdy dates|date=May 2020}}
{{Infobox Comet
| name            = C/1995 O1 (Hale–Bopp)<br>(Great Comet of 1997)
| image           = Comet Hale-Bopp 1995O1.jpg
| caption         = Comet Hale–Bopp, shortly after passing [[perihelion]] on April 4, 1997
| discovery_ref   = {{r|IAUC_6187}}
| discoverer      = {{ubl|[[Alan Hale (astronomer)|Alan Hale]]|[[Thomas Bopp]]}}
| discovery_site  = [[United States]]
| discovery_date  = July 23, 1995
| pronounced      = {{IPAc-en|,|h|ei|l|_|'|b|Q|p}}
| designations    = CJ95O010{{r|MPEC_1995-P01}}
| orbit_ref       = {{r|jpl1}}
| observation_arc = 29.2 years
| obs             = 66
| epoch           = 15 September 2022 ([[Julian day|JD]] 2459837.5)
| semimajor       = 177.43 AU
| perihelion      = 0.914 AU{{r|jpl1996}}
| aphelion        = 353.98 AU
| eccentricity    = 0.99498
| period          = ([[Barycentric coordinates (astronomy)|Barycentric]] 2,399 yr){{r|barycenter}}<br />{{nowrap|2,364–2,520 [[Julian year (astronomy)|yr]]{{r|NK1553}}}}
| inclination     = 89.288°
| asc_node        = 282.73°
| arg_peri        = 130.41°
| tjup            = 0.044
| Earth_moid      = 0.088 AU
| Jupiter_moid    = 0.079 AU
| physical_ref    = {{r|jpl1}}
| dimensions      = {{cvt|40–80|km|mi}}
| mean_diameter   = {{cvt|60|km|mi}}
| mean_radius     = {{cvt|30|km|mi}}
| rotation        = {{val|11.35|0.04}} hours{{r|Knight_2023}}
| albedo          = 0.01–0.07
| mass            = 1.9{{x10^|14}} kg{{r|Sosa_2011}}
| M1              = –1.3{{r|Kidger_1997}}
| M2              = 
| magnitude       = –1.8<br>{{small|(1997 apparition)}}
| last_p          = {{ubl|April 1, 1997{{r|jpl1996|MPEC_1995-P01}}|2215 BC{{r|Marsden_1997}}}}
| next_p          = ~4383–4387 AD{{r|Hale-Bopp4385}}
}}

'''Comet Hale–Bopp''' (formally designated '''C/1995&nbsp;O1''') is a long-period [[comet]] that was one of the most widely observed of the 20th century and one of the brightest seen for many decades.{{r|ICQ2|ICQ3|jpl2}}

[[Alan Hale (astronomer)|Alan Hale]] and [[Thomas Bopp]] discovered Comet Hale–Bopp separately on July 23, 1995, before it became visible to the [[naked eye]]. It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp exceeded most predictions when it passed [[perihelion]] on April 1, 1997, reaching about [[Magnitude (astronomy)#Examples|magnitude]] &minus;1.8. Its massive nucleus size made it visible to the naked eye for a record 18&nbsp;months.  This is twice as long as the [[Great Comet of 1811]], the previous record holder. 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 (astronomer)|Alan Hale]] and [[Thomas Bopp]], both in the United States.{{r|Shanklin_2000}}

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. The comet had an [[apparent magnitude]] of 10.5 and lay near the globular cluster [[Messier 70|M70]] in the constellation of [[Sagittarius (constellation)|Sagittarius]].{{r|IAUC_6187|Mobberley_2013}} Hale first established that there was no other [[deep-sky object]] near M70, and then consulted a directory of known comets, finding that none were known to be in this area of the sky. Once he had established that the object was moving relative to the background stars, he emailed the [[Central Bureau for Astronomical Telegrams]], the clearing house for astronomical discoveries at around 6:50 UT, shortly after his observations.{{r|Time-19970317}}<ref name=":0">{{Cite web |last=information@eso.org |title=New Distant Comet Headed for Bright Encounter - How Impressive Will Comet Hale-Bopp Become in 1997? |url=https://www.eso.org/public/news/eso9520/ |access-date=2025-11-13 |website=www.eso.org |language=pl}}</ref>

Bopp did not own a [[telescope]]. He was out with friends at Vekol Ranch, about 90 miles south of [[Phoenix, Arizona|Phoenix]] (near [[Stanfield, Arizona|Stanfield]]) , observing star clusters and [[galaxy|galaxies]] when he chanced across the comet while at the eyepiece of a homemade 17.5 inch [[Dobsonian telescope|Dobsonian]] telescope owned by his friend Jim Stevens.<ref>{{Cite web |date=2017-07-23 |title=Remembering Comet Hale-Bopp's Unlikely Discovery |url=https://www.mentalfloss.com/article/502889/remembering-comet-hale-bopps-unlikely-discovery |access-date=2025-11-13 |website=Mental Floss |language=en-US}}</ref> He realized he might have spotted something new when, like Hale, he checked his star maps to determine if any other deep-sky objects were known to be near M70, and found none. He alerted the Central Bureau for Astronomical Telegrams about two hours after Hale<ref name=":0" /> through a [[Western Union]] telegram. [[Brian G. Marsden]], who had run the bureau since 1968, laughed, "Nobody sends telegrams anymore. I mean, by the time that telegram got here, Alan Hale had already e-mailed us three times with updated coordinates."{{r|Newcott_1997}}

The following morning, it was confirmed that this was a new comet, and it was given the designation C/1995&nbsp;O1. The discovery was announced in [[International Astronomical Union]] circular 6187.{{r|IAUC_6187|Bopp_1997}}

== Early observation ==

Hale–Bopp's orbital position was calculated as 7.2&nbsp;[[astronomical units]] (au) from the Sun, placing it between [[Jupiter]] and [[Saturn]] and by far the greatest distance from Earth at which a comet had been discovered by amateurs.{{r|MPEC_1995-P01|Kidger_1996}} Most comets at this distance are extremely faint, and show no discernible activity, but Hale–Bopp already had an observable [[coma (cometary)|coma]].{{r|IAUC_6187}} A [[precovery]] image taken at the [[UK Schmidt Telescope]] in 1993 was found to show the then-unnoticed comet some 13&nbsp;AU (1.94 billion km or 1.21 billion miles)  from the Sun,{{r|IAUC_6198}} a distance at which most comets are essentially unobservable. ([[Comet Halley|Halley's Comet]] was more than 100 times fainter at the same distance from the Sun.){{r|Biver_1996}} Analysis indicated later that its [[comet nucleus]] was {{Convert|60 ± 20|km|mi|0|sp=us}} in diameter, approximately six times the size of [[Halley's Comet]].{{r|jpl1|Fernandez_2002}}

Its great distance and surprising activity indicated that comet Hale–Bopp might become very bright when it reached [[perihelion]] in 1997. However, comet scientists were wary – comets can be extremely unpredictable, and many have large outbursts at great distances only to diminish in brightness later. [[Comet Kohoutek]] in 1973 had been touted as a "comet of the century" and turned out to be unspectacular.{{r|Time-19970317}}

== Perihelion ==
[[File:Comet-Hale-Bopp-29-03-1997 hires adj.jpg|thumb|right|upright|The comet became a spectacular sight in early 1997.]]
[[File:Comet Hale-Bopp starmap 1997.png|thumb|Star map of path with 14-day motion marked]]
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,{{r|Kidger_2004}} 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 pollution|light-polluted]] skies.{{r|NYT-19970309}}

[[Internet|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. The Internet played a large role in encouraging the unprecedented public interest in comet Hale–Bopp.{{r|sciam-19970317}}

As the comet approached the Sun, it continued to brighten, shining at 2nd&nbsp;magnitude in February, and showing a growing pair of [[Comet tail|tails]], the blue gas tail pointing straight away from the Sun and the yellowish dust tail curving away along its orbit. On March 9, a [[Solar eclipse of March 9, 1997|solar eclipse]] in China, [[Mongolia]] and eastern [[Siberia]] allowed observers there to see the comet in the daytime.{{r|McGee_1997}} Hale–Bopp had its closest approach to Earth on March 22, 1997, at a distance of 1.315&nbsp;[[astronomical unit|au]] (196.72 million km or 122.24 million miles) .{{r|jpl5}}

As it passed perihelion on April 1, 1997, the comet developed into a spectacular sight. It shone brighter than any star in the sky except [[Sirius]], and its dust tail stretched 40–45 [[degree (angle)|degrees]] across the sky.{{r|West_1997a|Shylaja_1997}} The comet was visible well before the sky got fully dark each night, and while many great comets are very close to the Sun as they pass perihelion, comet Hale–Bopp was visible all night to [[Northern Hemisphere]] observers.{{r|West_1997b}}

== After perihelion ==
After its perihelion passage, the comet moved into the [[southern celestial hemisphere]]. The comet was much less impressive to [[Southern Hemisphere]] observers than it had been in the Northern Hemisphere, but southerners could 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&nbsp;days, or about {{frac|18|1|2}} months.{{r|Kidger_2004}} The previous record had been set by the [[Great Comet of 1811]], which was visible to the naked eye for about 9 months.{{r|Kidger_2004}}

The comet continued to fade as it receded, but was still tracked by astronomers. In October 2007, 10 years after the perihelion and at a distance of 25.7 [[Astronomical unit|au]] from the Sun, the comet was still active as indicated by the detection of the CO-driven coma.{{r|Szabó_2008}} [[Herschel Space Observatory]] images taken in 2010 suggest comet Hale–Bopp is covered in a fresh frost layer.{{r|Szabó_2012}} Hale–Bopp was again detected in December 2010 when it was 30.7&nbsp;AU away from the Sun,{{r|Szabó_2011}} and in 2012, at 33.2&nbsp;AU from the Sun.{{r|Herald_2012}} The [[James Webb Space Telescope]] observed Hale–Bopp in 2022, when it was 46.2&nbsp;AU from the Sun.{{r|MPEC_2022-S20}}

== Orbital changes ==
[[File:Hale-Bopp orbit.svg|thumb|right|Hale–Bopp at perihelion on April 1, 1997]]
{{multiple image
| align = right
| direction = vertical
| width = 220
| header = Animation of Hale–Bopp orbit
| image1 = Animation of Hale-Bopp orbit.gif
| caption1 = Polar view
| image2 = Animation of Hale–Bopp orbit - equatorial view.gif
| caption2 = Equatorial view
| footer = {{legend2|magenta|  Hale–Bopp }}{{·}}{{legend2|Cyan|[[Mercury (planet)|Mercury]]}}{{·}}{{legend2| OrangeRed |[[Venus]] }}{{·}}{{legend2|Royalblue|Earth}} {{·}}{{legend2|Gold|[[Mars]] }}{{·}}{{legend2|Lime|[[Jupiter]] }} }}

The comet likely made its previous [[perihelion]] approximately 4,200 years ago,{{r|Yeomans_1997}} roughly the year 2215&nbsp;BC.{{r|Marsden_1997}} The estimated closest approach to Earth was 1.4&nbsp;au, and it may have been observed in [[ancient Egypt]] during the [[6th dynasty]] reign of the Pharaoh [[Pepi II]] (Reign: 2247 – c. 2216 BC). Pepi's [[pyramid]] at [[Saqqara]] contains a text referring to an "nhh-star" as a companion of the pharaoh in the heavens, where "{{lang|egy|nhh}}" is the [[hieroglyph]] for long hair.{{r|Weeks_1998}}

Hale–Bopp may have had a near collision with Jupiter in 2215&nbsp;BC, which probably caused a dramatic change in its orbit, and 2215&nbsp;BC may have been its first passage through the inner Solar System from the [[Oort cloud]].{{r|Marsden_1997}} The comet's current orbit is almost [[perpendicular]] to the plane of the [[ecliptic]], so further close approaches to planets will be rare. However, in April 1996 the comet passed within {{convert|0.77|AU|e6km|abbr=unit}} of [[Jupiter]], close enough for its orbit to be measurably affected by the planet's [[gravity]].{{r|Yeomans_1997}} The comet's orbit was shortened considerably to a period of roughly 2,399&nbsp;years,{{r|barycenter}} and its next return to the inner [[Solar System]] will be [[List of future astronomical events#4th to 8th millennia|around the year 4385]].{{r|Hale-Bopp4385}} Its greatest distance from the Sun ([[aphelion]]) will be about 354&nbsp;AU,{{r|jpl1}} reduced from about 525&nbsp;AU.{{r|epoch1600|Marsden_1997|Williams_2005}}

The estimated probability of Hale–Bopp's striking Earth in future passages through the inner Solar System is remote, about 2.5×10<sup>−9</sup> per orbit.{{r|Weissman_2007}} However, given that the comet nucleus is around {{cvt|60|km|mi}} in diameter,{{r|jpl1}} the consequences of such an impact would be apocalyptic. Weissman conservatively estimates the diameter at {{cvt|35|km|mi}}; an estimated density of 0.6 g/cm<sup>3</sup> then gives a cometary mass of 1.3×10<sup>19</sup> g. At a probable impact velocity of 52.5&nbsp;km/s, impact energy can be calculated as 1.9×10<sup>32</sup> [[erg]]s, or 4.4×10<sup>9</sup> [[TNT equivalent|megatons]], about 44 times the estimated energy of the [[Alvarez hypothesis|K–T impact event]].{{r|Weissman_2007}}

Over many orbits, the cumulative effect of gravitational perturbations on comets with high orbital [[inclination]]s and small perihelion distances is generally to reduce the perihelion distance to very small values. Hale–Bopp has about a 15%&nbsp;chance of eventually becoming a [[sungrazing comet]] through this process.{{r|Bailey_1996}} If such is the case, it could undergo huge mass loss, or break up into smaller pieces like the [[Kreutz sungrazer]]s.  It would also be extremely bright, due to a combination of closeness to the Sun and nuclei size, potentially exceeding [[Halley's Comet]] in 837 AD.

== Scientific results ==
Due to the massive size of its nucleus, Comet Hale–Bopp was observed intensively by [[astronomer]]s during its perihelion passage, and several important advances in cometary science resulted from these observations. The dust production rate of the comet was very high (up to 2.0{{e|6}} kg/s),{{r|Jewitt_1999}} which may have made the inner coma [[Optical thickness|optically thick]].{{r|Fernandez_1999}} Based on the properties of the dust grains{{snd}}high temperature, high [[albedo]] and strong 10&nbsp;μm silicate emission feature{{snd}}the astronomers concluded the dust grains are smaller than observed in any other comet.{{r|Mason_2001}}

Hale–Bopp showed the highest ever linear polarization detected for any comet. Such polarization is the result of solar radiation getting scattered by the dust particles in the coma of the comet and depends on the nature of the grains. It further confirms that the dust grains in the coma of comet Hale–Bopp were smaller than inferred in any other comet.{{r|Ganesh_1998}}

=== Sodium tail ===
[[File:Hale-Bopp sodium tail.gif|thumb|right|Comet Hale–Bopp's neutral sodium tail (the straight tail extending up to the left from the nucleus){{r|Cremonese_1997a}}]]
One of the most remarkable discoveries was that the comet had a third type of tail. In addition to the well-known gas and dust tails, Hale–Bopp also exhibited a faint [[sodium]] tail, only visible with powerful instruments with dedicated filters. Sodium emission had been previously observed in other comets, but had not been shown to come from a tail. Hale–Bopp's sodium tail consisted of [[electric charge|neutral atoms]] (not [[ion]]s), and extended to some {{convert|0.33|au|e6km e6mi|abbr=unit}} in length.{{r|Cremonese_1997a}}

The source of the sodium appeared to be the inner [[coma (cometary)|coma]], although not necessarily the [[comet nucleus|nucleus]]. There are several possible mechanisms for generating a source of sodium atoms, including collisions between dust grains surrounding the nucleus, and "sputtering" of sodium from dust grains by [[ultraviolet]] light. It is not yet established which mechanism is primarily responsible for creating Hale–Bopp's sodium tail, and the narrow{{r|Cremonese_1997a}} and diffuse{{r|Wilson_1998}} components of the tail may have different origins.{{r|Cremonese_1997b}}

While the comet's dust tail roughly followed the path of the comet's orbit and the gas tail pointed almost directly away from the Sun, the sodium tail appeared to lie between the two. This implies that the sodium atoms are driven away from the comet's head by [[radiation pressure]].{{r|Cremonese_1997a}}

=== Deuterium abundance ===
The abundance of [[deuterium]] in comet Hale–Bopp in the form of [[heavy water]] was found to be about twice that of Earth's oceans. If Hale–Bopp's deuterium abundance is typical of all comets, this implies that although cometary impacts are thought to be the source of a significant amount of the [[Origin of water on Earth|water on Earth]], they cannot be the only source.{{r|Meier_1999}}

Deuterium was also detected in many other [[hydrogen]] compounds in the comet. The ratio of deuterium to normal hydrogen was found to vary from compound to compound, which astronomers believe suggests that cometary ices were formed in [[interstellar cloud]]s, rather than in the [[solar nebula]]. Theoretical modelling of ice formation in interstellar clouds suggests that comet Hale–Bopp formed at temperatures of around 25–45&nbsp;[[kelvin]].{{r|Meier_1999}} ( –414 to –387 Fahrenheit / –248 to –233 Celsius).

=== Organics ===
Spectroscopic observations of Hale–Bopp revealed the presence of many [[organic chemistry|organic chemicals]], several of which had never been detected in comets before. These complex molecules may exist within the cometary nucleus, or might be synthesised by reactions in the comet.{{r|Rodgers_2001}}

=== Detection of argon ===
Hale–Bopp was the first comet where the [[noble gas]] [[argon]] was detected.{{r|Stern_2000}} Noble gases are chemically inert and vary from low to high [[Volatility (chemistry)|volatility]]. Since different noble elements have different [[Sublimation (phase transition)|sublimation]] temperatures, and don't interact with other elements, they can be used for probing the temperature histories of the cometary ices. [[Krypton]] has a sublimation temperature of 16–20&nbsp;K (−430 to −423 Fahrenheit/ −257 to −253 Celsius) and was found to be depleted more than 25 times relative to the solar abundance,{{r|Krasnopolsky_1997}} while argon with its higher sublimation temperature was enriched relative to the solar abundance.{{r|Stern_2000}} Together these observations indicate that the interior of Hale–Bopp has always been colder than 35–40&nbsp;K (−396 to −387 Fahrenheit / −238 to −233 Celsius), but has at some point been warmer than 20&nbsp;K (−423 Fahrenheit / −253 Celsius). Unless the solar nebula was much colder and richer in argon than generally believed, this suggests that the comet formed beyond Neptune in the [[Kuiper belt]] region and then migrated outward to the [[Oort cloud]].{{r|Stern_2000}}

=== Rotation ===
Comet Hale–Bopp's activity and outgassing were not spread uniformly over its nucleus, but instead came from several specific jets. Observations of the material streaming away from these jets allowed astronomers to measure the rotation period of the comet,{{r|jpl4}} which was found to be about 11 hours 46 minutes.{{r|Warell_1999}}

=== Binary nucleus question ===
In 1997 a paper was published that hypothesised the existence of a binary [[comet nucleus|nucleus]] to fully explain the observed pattern of comet Hale–Bopp's dust emission observed in October 1995. The paper was based on theoretical analysis, and did not claim an observational detection of the proposed satellite nucleus, but estimated that it would have a diameter of about {{cvt|30|km|mi}}, with the main nucleus being about {{cvt|70|km|mi}} across, and would orbit in about three days at a distance of about {{cvt|180|km|mi}}.{{r|Sekanina_1997a}} This analysis was confirmed by observations in 1996 using Wide-Field Planetary Camera 2 of the [[Hubble Space Telescope]] which had taken images of the comet that revealed the satellite.{{r|Sekanina_1997a}}

Although observations using [[adaptive optics]] in late 1997 and early 1998 showed a double peak in the brightness of the nucleus,{{r|Marchis_1999}} controversy still exists over whether such observations can only be explained by a binary nucleus.{{r|Fernandez_2002}} The discovery of the satellite was not confirmed by other observations.{{r|McCarthy_2007|Weaver_1999}} Also, while comets have been observed to break up before,{{r|Sekanina_1997b}} no case had been found of a stable binary nucleus until the subsequent discovery of [[P/2006 VW139|{{mp|P/2006 VW|139}}]].

== UFO claims ==
{{main|Heaven's Gate (religious group)}}
In November 1996, amateur astronomer Chuck Shramek of [[Houston]], Texas, took a [[charge-coupled device|CCD]] image of the comet which showed a fuzzy, slightly elongated object nearby. His computer sky-viewing program did not identify the star, so Shramek called the [[Art Bell]] radio program ''[[Coast to Coast AM]]'' to announce that he had discovered a "Saturn-like object" following Hale–Bopp. UFO enthusiasts, such as [[remote viewing]] proponent and [[Emory University]] political science professor [[Courtney Brown (researcher)|Courtney Brown]], soon concluded that there was an alien spacecraft following the comet.{{r|Time-19970414}}

Several astronomers, including Alan Hale, stated that the object was simply the 8.5-magnitude star SAO141894.{{r|Hale_1997}} They noted that the star did not appear on Shramek's computer program because the user preferences were set incorrectly.{{r|Burnham_2000}} Art Bell claimed to have obtained an image of the object from an anonymous astrophysicist who was about to confirm its discovery. However, astronomers [[Olivier R. Hainaut|Olivier Hainaut]] and [[David J. Tholen|David Tholen]] of the [[University of Hawaii]] stated that the alleged photo was an altered copy of one of their own comet images.{{r|Tholen_1997}}

Thirty-nine members of the [[Heaven's Gate (religious group)|Heaven's Gate]] cult died in a [[mass suicide]], in March 1997 with the intention of teleporting to a spaceship which they believed was flying behind the comet.{{r|Robinson_2006}}

Nancy Lieder, who claims to receive messages from aliens through an implant in her brain, stated that Hale–Bopp was a fiction designed to distract the population from the coming arrival of [[Nibiru cataclysm|"Nibiru"]] or "Planet X", a giant planet whose close passage would disrupt the Earth's rotation, causing global cataclysm.{{r|NYT-19970328}} Her original date for the apocalypse was May 2003, which passed without incident, but various conspiracy websites continued to predict the coming of Nibiru, most of whom tied it to the [[2012 phenomenon]].{{r|Morrison_2008}} Lieder and others' claims of the planet Nibiru have been repeatedly debunked by scientists.{{r|Space.com1}}

== Legacy ==
[[File:ESO-Comet Hale-Bopp-Phot-07a-01-hires.jpg|thumb|right| Comet Hale–Bopp in 2001, at a distance of nearly two billion kilometres from the Sun. Credit: [[ESO]]]]
Its lengthy period of visibility and extensive coverage in the media meant that Hale–Bopp was probably the most-observed comet in history, making a far greater impact on the general public than the return of [[Comet Halley|Halley's Comet]] in 1986, and certainly seen by a greater number of people than witnessed any of Halley's previous appearances. For instance, 69% of Americans had seen Hale–Bopp by April 9, 1997.{{r|Aguirre_1997}}

Hale–Bopp was a record-breaking comet{{snd}}the farthest comet from the Sun discovered by amateurs,{{r|jpl5}} with the largest well-measured cometary nucleus known after [[95P/Chiron]],{{r|Fernandez_2002}} and it was visible to the naked eye for twice as long as the previous record-holder.{{r|Kidger_2004}} It was also brighter than magnitude&nbsp;0 for eight&nbsp;weeks, longer than any other recorded comet.{{r|jpl5}}

[[Carolyn S. Shoemaker|Carolyn Shoemaker]] and her husband [[Eugene Merle Shoemaker|Gene]], co-discoverers of [[comet Shoemaker–Levy 9]], were involved in a car crash after photographing the comet. Gene died in the crash and his ashes were sent to the Moon aboard NASA's ''[[Lunar Prospector]]'' mission along with an image of Hale–Bopp, "the last comet that the Shoemakers observed together".{{r|jpl3}}

Composer Dmitry Kayukin created the music album ''Comet 97'' based on his memories of observing Comet Hale–Bopp.{{r|Kayukin_2023}}

== See also ==
* [[Comet Hyakutake]]
* [[Hale Bopp (Waterhouse)|''Hale Bopp'' (Waterhouse)]], a 1997 string orchestra composition 
* [[Lists of comets]]
{{clear}}

== References ==
{{Reflist|refs=

<ref name="Aguirre_1997">{{cite magazine
| author1= E. L. Aguirre
| title= The Great Comet of 1997
| url= https://pqasb.pqarchiver.com/skyandtelescope/access/886291661.html?dids=886291661:886291661&FMT=CITE&FMTS=CITE:PAGE&date=Jul+1997&author=Edwin+L+Aguirre&desc=The+Great+Comet+of+1997
| magazine= Sky & Telescope
| date= July 1997
| access-date= 5 July 2017
| archive-date= 16 January 2009
| archive-url= https://web.archive.org/web/20090116131943/http://pqasb.pqarchiver.com/skyandtelescope/access/886291661.html?dids=886291661:886291661&FMT=CITE&FMTS=CITE:PAGE&date=Jul+1997&author=Edwin+L+Aguirre&desc=The+Great+Comet+of+1997
| url-status= dead }}
</ref>

<ref name="Bailey_1996">{{cite journal
| author1= M. E. Bailey
| author2= V. V. Emelʹyanenko
| author3= G. Hahn
| author4= N. W. Harris
| author5= K. A. Hughes
| author6= K. Muinonen
| author7= J. V. Scotti
| display-authors= 4
| title= Orbit Determination and Evolution of Comet C/1995 O1 (Hale–Bopp)
| journal= [[Monthly Notices of the Royal Astronomical Society]]
| year= 1996
| volume= 281
| issue= 1
| pages= 916–924
| citeseerx=10.1.1.29.6010
| bibcode=1996MNRAS.281..916B
| doi= 10.1093/mnras/281.3.916
| doi-access= free }}
</ref>

<ref name="barycenter">{{cite web 
| author= [[JPL Horizons On-Line Ephemeris System|Horizons]] output
| title= Barycentric Osculating Orbital Elements for Comet C/1995 O1 (Hale–Bopp)
| url= https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27Hale-Bopp%27&TABLE_TYPE=%27ELEMENTS%27&START_TIME=%272022-Sep-15%27&STOP_TIME=%272022-Sep-16%27&STEP_SIZE=%27100%20years%27&CENTER=%27@0%27&OUT_UNITS=%27AU-D%27 
| access-date= 18 September 2022 }} (Solution using the Solar System [[barycenter]]. "PR = 8.763E+05 / 365.25 days" = 2399 years)
</ref>

<ref name="Biver_1996">{{cite journal
| author1= N. Biver
| author2= H. Rauer
| author3= D. Despois
| author4= R. Moreno
| author5= G. Paubert
| author6= D. Bockelée-Morvan
| author7= P. Colom
| author8= J. Crovisier
| author9= E. Gérard
| author10= L. Jorda
| display-authors= 5
| title= Substantial outgassing of CO from Comet Hale–Bopp at large heliocentric distance
| journal= Nature
| year= 1996
| volume= 380
| issue= 6570
| pages= 137–139
| bibcode= 1996Natur.380..137B
| s2cid= 4342525
| pmid= 8600385
| doi= 10.1038/380137a0 }}
</ref>

<ref name="Bopp_1997">{{cite journal
| author1= T. Bopp
| title= Amateur Contributions in the study of Comet Hale–Bopp
| journal= Earth, Moon, and Planets
| year= 1997
| volume= 79
| issue= 1–3
| pages= 307–308
| bibcode= 1997EM&P...79..307B
| s2cid= 117124838
| doi= 10.1023/A:1006262006364 }}
</ref>

<ref name="Burnham_2000">{{cite book
| author1= R. Burnham
| author2= D. H. Levy
| title= Great Comets
| url= https://archive.org/details/greatcomets00burn/page/191
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| url= http://www.time.com/time/magazine/article/0,9171,986055,00.html
| archive-date = November 30, 2008
| magazine= Time
| date= 17 March 1997 
| access-date= 30 October 2008
| archive-url= https://web.archive.org/web/20081130085357/http://www.time.com/time/magazine/article/0,9171,986055,00.html
| url-status = dead }}
</ref>

<ref name="Time-19970414">{{cite magazine
| author1= L. Jaroff
| author2= J. Willwerth
| title= The Man who Spread the Myth
| url = http://www.time.com/time/magazine/article/0,9171,986171,00.html
| magazine= Time
| date= 14 April 1997
| access-date= 30 October 2008
| archive-date= 21 November 2005
| archive-url= https://web.archive.org/web/20051121060305/http://www.time.com/time/magazine/article/0,9171,986171,00.html
| url-status= dead }}
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<ref name="Warell_1999">{{cite journal
| author1= J. Warell
| author2= C. I. Lagerkvist
| author3= J. S. V. Lagerros
| title= Dust continuum imaging of C/1995 O1 (Hale–Bopp): Rotation period and dust outflow velocity 
| journal= Astronomy and Astrophysics Supplement Series
| year= 1999
| volume= 136
| issue= 2
| pages= 245–256
| bibcode= 1999A&AS..136..245W
| doi= 10.1051/aas:1999213
| doi-access= free }}
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<ref name="Weaver_1999">{{cite journal 
| author1= H. A. Weaver
| author2= P. D. Feldman
| author3= M. F. a'Hearn
| author4= C. Arpigny
| author5= J. C. Brandt
| author6= S. A. Stern
| display-authors= 3
| title= Post-Perihelion HST Observations of Comet Hale–Bopp (C/1995 O1)
| year= 1999
| journal= Icarus
| volume= 141
| issue= 1
| pages= 1–12
| bibcode= 1999Icar..141....1W
| doi= 10.1006/icar.1999.6159
| doi-access= free }}
</ref>

<ref name="Weeks_1998">{{cite book
| author1= K. R. Weeks
| title= The Lost Tomb: The Greatest Discovery at the Valley of the Kings Since Tutankhamun
| url= https://books.google.com/books?id=LWxYHQAACAAJ
| publisher= Phoenix
| year= 1998
| page= 198
| isbn= 978-0-753-80681-4 }}
</ref>

<ref name="Weissman_2007">{{Cite journal
| author1= P. R. Weissman
| title= The cometary impactor flux at the Earth
| journal= Proceedings of the International Astronomical Union
| publisher= [[Cambridge University Press]]
| year= 2007
| volume= 2
| issue= S236
| pages= 441–450
| bibcode= 2007IAUS..236..441W
| isbn= 978-0-521-86345-2
| doi= 10.1017/S1743921307003559
| doi-access= free }}
</ref>

<ref name="West_1997a">{{cite web
| author1= R. M. West
| title= Comet Hale–Bopp
| url= http://www.eso.org/public//events/astro-evt/hale-bopp/comet-hale-bopp-summary-apr13-97-rw.html
| date= 13 April 1997
| publisher= [[European Southern Observatory]]
| access-date= 23 November 2008
| archive-date= 24 May 2011
| archive-url= https://web.archive.org/web/20110524134423/http://www.eso.org/public/events/astro-evt/hale-bopp/comet-hale-bopp-summary-apr13-97-rw.html
| url-status= dead }}
</ref>

<ref name="West_1997b">{{cite web
| author1= R. M. West
| title= Comet Hale–Bopp
| url= http://www.eso.org/public//events/astro-evt/hale-bopp/comet-hale-bopp-summary-mar07-97-rw.html
| publisher= [[European Southern Observatory]]
| date= 7 March 1997
| access-date= 25 November 2008
| archive-date= 24 May 2011
| archive-url= https://web.archive.org/web/20110524135044/http://www.eso.org/public/events/astro-evt/hale-bopp/comet-hale-bopp-summary-mar07-97-rw.html
| url-status= dead }}
</ref>

<ref name="Williams_2005">{{cite web
| author1= D. R. Williams
| title= Comet Fact Sheet
| url= http://nssdc.gsfc.nasa.gov/planetary/factsheet/cometfact.html
| publisher= [[NASA]]
| date= 23 December 2005
| access-date= 5 December 2008
| archive-date= June 2, 2011
| archive-url= https://web.archive.org/web/20110602102215/http://nssdc.gsfc.nasa.gov/planetary/factsheet/cometfact.html
| url-status= dead
}} (pre-[[Perturbation (astronomy)|perturbation]] orbit: semi-major axis 250 AU; period 4000yr)</ref>

<ref name="Wilson_1998">{{cite journal 
| author1= J. K. Wilson
| author2= J. Baumgardner
| author3= M. Mendillo
| title= Three tails of comet Hale–Bopp 
| journal= Geophysical Research Letters
| year= 1998
| volume= 25
| issue= 3
| pages= 225–228
| bibcode= 1998GeoRL..25..225W
| s2cid= 129323918
| doi= 10.1029/97GL03704
| doi-access= free }}
</ref>

<ref name="Yeomans_1997">{{cite web
| author1= D. K. Yeomans
| title= Comet Hale–Bopp Orbit and Ephemeris Information
| url= http://www2.jpl.nasa.gov/comet/ephemjpl8.html
| publisher= [[NASA]] / [[Jet Propulsion Laboratory|JPL]]
| date= 10 April 1997
| access-date= 23 October 2008}}
</ref>

}}

== External links ==
{{Commons category|Comet Hale-Bopp}}
* [http://cometbase.net/en/observation/listObserv/478 CometBase: Comet Hale–Bopp]
* [http://www.cometography.com/lcomets/1995o1.html Cometography.com: Comet Hale–Bopp]
* [http://www.jpl.nasa.gov/comet NASA Hale–Bopp page] {{Webarchive|url=https://web.archive.org/web/20110821073111/http://www2.jpl.nasa.gov/comet/ |date=August 21, 2011 }}
* [https://web.archive.org/web/20110827030726/http://shadowandsubstance.com/Past%20graphics/Comet%20Hale-Bopp%20orbit.htm Shadow and Substance.com: Static orbital diagram]
* [https://web.archive.org/web/20070929083554/http://one.revver.com/watch/90657/flv/affiliate/14715 Comet Nucleus Animation]
* {{cite journal |arxiv=1404.2562|doi=10.1016/j.icarus.2014.03.033|bibcode=2014Icar..236..136K|title=A dynamical analysis of the dust tail of Comet C/1995 O1 (Hale–Bopp) at high heliocentric distances|year=2014|last1=Kramer|first1=Emily A.|last2=Fernandez|first2=Yanga R.|last3=Lisse|first3=Carey M.|last4=Kelley|first4=Michael S.P.|last5=Woodney|first5=Laura M.|s2cid=119201510|journal=Icarus|volume=236|pages=136–145}}
* [https://hdr-astrophotography.com/simulations-of-past-comets/ HDR Astrophotography: Simulations Atlas of Past Comets (1900 to 1999)] by Nicolas Lefaudeux
* {{JPL Small Body|name=Hale–Bopp|id=1000132}}

{{Comets}}
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{{DEFAULTSORT:Hale-Bopp, 1995 O1}}
[[Category:Non-periodic comets]]
[[Category:Great comets]]
[[Category:Near-Earth comets]]
[[Category:Heaven's Gate (religious group)]]
[[Category:1997 in science]]
[[Category:Astronomical objects discovered in 1995|19950723]]
[[Category:Discoveries by amateur astronomers]]