View source for Comet Hyakutake

{{Short description|Great Comet of 1996}}
{{Use dmy dates|date=February 2023}}
{{Infobox comet
| name            = C/1996 B2 (Hyakutake)<br/>(Great Comet of 1996)
| image           = File:Hyakutake Color.jpg
| caption         = Comet Hyakutake pictured during its closest approach to Earth on 25 March 1996
| discovery_ref   = {{r|IAUC_6299}}
| discoverer      = [[Yuji Hyakutake]]
| discovery_site  = [[Kagoshima, Japan]]
| discovery_date  = 31 January 1996
| mpc_name        = 
| pronounce       = {{IPA|ja|çakɯ̥take}}
| designations    = 
| orbit_ref       = {{r|barycenter|ESO_2009|jpldata}}
| epoch           = 15 March 1996 ([[Julian day|JD]] 2450157.5)
| observation_arc =
| obs             =
| aphelion        = ~1,320 AU (inbound){{ref_label|A|a|none}}<br/>~3,500 AU (outbound)
| perihelion     = 0.230 AU
| semimajor      = 1,700 AU (outbound){{ref_label|A|a|none}}
| eccentricity   = 0.99989
| period         = ~17,000 years (inbound){{ref_label|A|a|none}}<br/>~72,000 years (outbound)
| inclination    = 124.922°
| asc_node       = 188.045°
| arg_peri       = 130.175°
| long_peri      =
| tjup           = –0.338
| Earth_moid     = 0.101 AU
| Jupiter_moid   = 1.991 AU
| physical_ref   = {{r|jpldata}}
| dimensions     = {{cvt|4.2|km|mi}}
| mass           = 1.9{{x10^|12}} kg{{r|Sosa_2011}}
| sidereal_day   = {{val|6.273|0.007}} hours{{r|Knight_2023}}
| M1             = 7.4
| M2             = 11.1
| magnitude      = 0.0<br/><small>(1996 apparition)</small>
| last_p         = 1 May 1996
| next_p         = 
}}

'''Comet Hyakutake''' ([[Astronomical naming conventions#Comets|formally designated]] '''C/1996 B2''') is a [[comet]] discovered on 31 January 1996.{{r|IAUC_6299}} It was dubbed the '''Great Comet of 1996'''; its passage to within {{cvt|0.1|AU|Gm|lk=in}} 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 [[Comet#Orbital characteristics|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&nbsp;years,{{r|barycenter|James_1998}} but the [[gravitational]] [[Perturbation (astronomy)|perturbation]] of the [[giant planet]]s has increased this period to 70,000&nbsp;years.{{r|barycenter|James_1998}} 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 [[atom]]s in the [[coma (cometary)|coma]] of the comet. The [[Ulysses probe|''Ulysses'' spacecraft]] fortuitously crossed the comet's tail at a distance of more than {{convert|500|e6km|AU e6mi|abbr=unit}} from the [[comet nucleus|nucleus]], showing that Hyakutake had the longest tail known for a comet.

== Discovery ==
The comet was discovered on 30 January 1996,{{r|IAUC_6299}} by [[Yuji Hyakutake]], an [[amateur]] [[astronomer]] from southern Japan.{{r|Baalke_1996}} He had been searching for comets for years and had moved to [[Kagoshima Prefecture]] partly for the dark skies in nearby rural areas. He was using a powerful set of [[binoculars]] with {{cvt|150|mm|0}} [[objective lens]]es to scan the skies on the night of the discovery.{{r|Aguirre_1996}}

This comet was actually the second Comet Hyakutake; Hyakutake had discovered comet [[C/1995 Y1]] several weeks earlier.{{r|Tenmon_1996}} While re-observing his first comet (which never became visible to the [[naked eye]]) and the surrounding patch of sky, Hyakutake was surprised to find another comet in almost the same position as the first had been. Hardly believing a second discovery so soon after the first, Hyakutake reported his observation to the [[National Astronomical Observatory of Japan]] the following morning.{{r|Hyakutake_1996}} Later that day, the discovery was confirmed by independent observations.{{r|IAUC_6303}}

At the time of its discovery, the comet was shining at [[apparent magnitude|magnitude]] 11.0 and had a coma approximately 2.5&nbsp;[[arcminute]]s across. It was approximately 2&nbsp;[[astronomical unit]]s (AU) from the [[Sun]].{{r|harvard1}} Later, a [[precovery]] image of the comet was found on a photograph taken on January 1, when the comet was about 2.4&nbsp;AU from the Sun and had a magnitude of 13.3.{{r|James_1998}}

== Orbit ==
[[File:Comet Hyakutake inner solar system 1996.png|thumb|320px|left|Comet Hyakutake's trajectory through the inner solar system, with a high inclination, passed closest to the Earth in late March 1996, passing over Earth's north pole. It was at perihelion on May 1.]]

When the first calculations of the comet's [[orbit]] were made, scientists realized that it was going to pass just 0.1&nbsp;AU from Earth on 25 March.{{r|Minter_1996}} Only four comets in the previous century had passed closer.{{r|ESO_1996}} [[Comet Hale–Bopp]] was already being discussed as a possible "[[great comet]]"; the astronomical community eventually realised that Hyakutake might also become spectacular because of its close approach.{{r|NOVA_1997}}

Moreover, Comet Hyakutake's orbit meant that it had last been to the inner [[Solar System]] approximately 17,000&nbsp;years earlier.{{r|barycenter}} Because it had probably passed close to the Sun several times before,{{r|James_1998}} the approach in 1996 would not be a maiden arrival from the [[Oort cloud]], a place from where comets with orbital periods of millions of years come. Comets entering the inner Solar System for the first time may brighten rapidly before fading as they near the Sun, because a layer of highly volatile material evaporates. This was the case with [[Comet Kohoutek]] in 1973; it was initially touted as potentially spectacular, but only appeared moderately bright. Older comets show a more consistent brightening pattern.{{r|Whipple_1978}} Thus, all indications suggested Comet Hyakutake would be bright.{{r|NOVA_1997}}

Besides approaching close to Earth, the comet would also be visible throughout the night to [[Northern Hemisphere]] observers at its closest approach because of its path, passing very close to the [[pole star]]. This would be an unusual occurrence, because most comets are close to the Sun in the sky when the comets are at their brightest, leading to the comets appearing in a sky not completely dark.{{r|skyguide1}}

== Earth passage ==
Hyakutake became visible to the naked eye in early March 1996. By mid-March, the comet was still fairly unremarkable, shining at 4th [[Apparent magnitude|magnitude]] with a tail about 5&nbsp;[[degree (angle)|degrees]] long. As it neared its closest approach to Earth, it rapidly became brighter, and its tail grew in length. By March 24, the comet was one of the brightest objects in the night sky, and its tail stretched 35&nbsp;degrees. The comet had a notably bluish-green colour.{{r|James_1998}}

[[File:Komet_Hyakutake_von_Franz_Haar_(1).jpg|left|thumb|Comet Hyakutake photographed by Franz Haar in March 1996]]
The closest approach occurred on 25 March at a distance of {{Convert|0.1|AU|e6km LD|abbr=unit}}.{{r|jpldata}} Hyakutake was moving so rapidly across the night sky that its movement could be detected against the stars in just a few minutes; it covered the [[diameter]] of a [[full moon]] (half a degree) every 30&nbsp;minutes. Observers estimated its magnitude as around 0, and tail lengths of up to 80&nbsp;degrees were reported.{{r|James_1998}} Its coma, now close to the [[zenith]] for observers at mid-northern [[latitude]]s, appeared approximately 1.5 to 2&nbsp;degrees across, roughly four times the diameter of the full moon.{{r|James_1998}} The comet's head appeared distinctly blue-green, possibly due to emissions from [[diatomic carbon]] (C<sub>2</sub>) combined with sunlight reflected from dust grains.{{r|Skartlien_1996}}

Because Hyakutake was at its brightest for only a few days, it did not have time to permeate the public imagination in the way that [[Comet Hale–Bopp]] did the following year. Many European observers in particular did not see the comet at its peak because of unfavourable weather conditions.{{r|James_1998}}

== Perihelion and afterwards ==
After its close approach to the Earth, the comet faded to about 2nd magnitude. It reached [[perihelion]] on 1 May 1996, brightening again and exhibiting a dust tail in addition to the gas tail seen as it passed the Earth. By this time, however, it was close to the Sun and was not seen as easily. It was observed passing perihelion by the [[Solar and Heliospheric Observatory|''SOHO'']] Sun-observing [[satellite]], which also recorded a large [[coronal mass ejection]] being formed at the same time. The comet's distance from the Sun at perihelion was 0.23&nbsp;AU, well inside the orbit of [[Mercury (planet)|Mercury]].{{r|ESO_1996}}

After its perihelion passage, Hyakutake faded rapidly and was lost to naked-eye visibility by the end of May. Its orbital path carried it rapidly into the southern skies, but following perihelion it became much less monitored. The last known observation of the comet took place on November 2.{{r|Nakano_2008}}

Hyakutake had passed through the inner Solar System approximately 17,000&nbsp;years ago; gravitational interactions with the [[gas giants]] during its 1996 passage stretched its orbit greatly, and [[Barycentric coordinates (astronomy)|barycentric fits]] to the comet's orbit predict it will not return to the inner [[Solar System]] again for approximately 70,000 years.{{r|barycenter|James_1998}}{{ref_label|A|a|none}}

== Scientific results ==

=== Spacecraft passes through the tail ===
[[File:Animation of Ulysses trajectory.gif|thumb|right|Animation of ''Ulysses''{{'}} trajectory from 6 October 1990 to 29 June 2009<br/>{{legend2|magenta|''Ulysses''}}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2|Gold|[[Jupiter]]}}{{·}}{{legend2|Cyan|[[C/2006 P1]]}}{{·}}{{legend2|Lime|C/1996 B2}}{{·}}{{legend2|OrangeRed|[[C/1999 T1]]}}]]
The [[Ulysses (spacecraft)|''Ulysses'' spacecraft]] made an unexpected pass through the tail of the comet on 1 May 1996.{{r|physicsworld1}} Evidence of the encounter was not noticed until 1998. Astronomers analysing old data found that ''Ulysses''{{'}} instruments had detected a large drop in the number of [[proton]]s passing, as well as a change in the direction and strength of the local [[magnetic field]]. This implied that the spacecraft had crossed the 'wake' of an object, most likely a comet; the object responsible was not immediately identified.{{r|Jones_2002}}

In 2000, two teams independently analyzed the same event. The [[magnetometer]] team realized that the changes in the direction of the magnetic field mentioned above agreed with the "draping" pattern expected in a comet's ion, or plasma tail. The magnetometer team looked for likely suspects. No known comets were located near the satellite, but looking further afield, they found that Hyakutake, {{convert|500|e6km|AU|abbr=unit}} away, had crossed ''Ulysses''{{'}} orbital plane on 23 April 1996. The [[solar wind]] had a velocity at the time of about {{cvt|750|km/s}}, at which speed it would have taken eight days for the tail to be carried out to where the spacecraft was situated at 3.73&nbsp;AU, approximately 45 degrees out of the [[ecliptic]] plane. The orientation of the ion tail inferred from the magnetic field measurements agreed with the source lying in Comet Hyakutake's orbital plane.{{r|Jones_2000}}

The other team, working on data from the spacecraft's ion composition spectrometer, discovered a sudden large spike in detected levels of [[ion]]ised particles at the same time. The relative abundances of chemical elements detected indicated that the object responsible was definitely a comet.{{r|Gloeckler_2000}}

Based on the ''Ulysses'' encounter, the comet's tail is known to have been at least 570&nbsp;million&nbsp;km (360&nbsp;million&nbsp;miles; 3.8&nbsp;AU) long. This is almost twice as long as the previous longest-known cometary tail, that of the [[Great Comet of 1843]], which was 2&nbsp;AU long.{{r|Jones_2000}} This  record was broken in 2002 by comet [[153P/Ikeya–Zhang]], which had a tail-length of at least {{val|7.46|u=AU}}.{{r|Jones_2006}}

=== Composition ===
Terrestrial observers found [[ethane]] and [[methane]] in the comet, the first time either of these gases had been detected in a comet. Chemical analysis showed that the abundances of ethane and methane were roughly equal, which may imply that its ices formed in interstellar space, away from the Sun, which would have evaporated these volatile molecules. Hyakutake's ices must have formed at temperatures of 20&nbsp;[[Kelvin|K]] or less, indicating that it probably formed in a denser-than-average interstellar cloud.{{r|Mumma_1996}}

The amount of [[deuterium]] in the comet's water ices was determined through [[astronomical spectroscopy|spectroscopic]] observations. It was found that the ratio of deuterium to [[hydrogen]] (known as the D/H ratio) was about 3{{E|−4}}, which compares to a value in Earth's oceans of about 1.5{{E|−4}}. It has been proposed that cometary collisions with Earth might have supplied a large proportion of the water in the oceans, but the high D–H ratio measured in Hyakutake and other comets such as Hale–Bopp and [[Halley's Comet]] have caused problems for this theory.{{r|Bockelée-Morvan_1998}}

=== X-ray emission ===
[[File:X-rays from Hyakutake.jpg|thumb|right|150px|[[X-ray]] emission from Hyakutake, as seen by the [[ROSAT]] satellite]]

One of the great surprises of Hyakutake's passage through the inner Solar System was the discovery that it was emitting [[X-rays]], with observations made using the ''[[ROSAT]]'' satellite revealing very strong X-ray emission.{{r|Glanz_1996}} This was the first time a comet had been seen to do so, but astronomers soon found that almost every comet they looked at was emitting X-rays. The emission from Hyakutake was brightest in a crescent shape surrounding the nucleus with the ends of the crescent pointing away from the Sun.{{r|Cravens_2002}}

The cause of the X-ray emission is thought to be a combination of two mechanisms. Interactions between energetic solar wind particles and cometary material evaporating from the nucleus is likely to contribute significantly to this effect.{{r|Lisse_1996}} [[Thomas E. Cravens]] was the first to propose an explanation in early 1997.<ref>{{cite journal
| last = Cravens
| first = T. E.
| date = 1997
| title = Comet Hyakutake x-ray source: Charge transfer of solar wind heavy ions
| journal = Geophysical Research Letters
| volume = 24
| issue = 1
| page = 105
| doi = 10.1029/96GL03780
| bibcode = 1997GeoRL..24..105C
}}</ref> Reflection of solar X-rays is seen in other Solar System objects such as the [[Moon]], but a simple calculation assuming even the highest X-ray reflectivity possible per molecule or dust grain is not able to explain the majority of the observed flux from Hyakutake, as the comet's atmosphere is very tenuous and diffuse. Observations of comet [[C/1999 S4 (LINEAR)]] with the [[Chandra X-ray Observatory|''Chandra'' satellite]] in 2000 determined that X-rays observed from that comet were produced predominantly by charge exchange collisions between highly charged [[carbon]], [[oxygen]] and [[nitrogen]] minor ions in the solar wind, and neutral water, oxygen and hydrogen in the comet's coma.{{r|Lisse_2001}}

=== Nucleus size and activity ===
[[File:Comet Hyakutake from Hubble.jpg|thumb|left|Comet Hyakutake captured by the [[Hubble Space Telescope]] on 4 April 1996, with an [[infrared filter]]]]

[[File:Nucleus of Hyakutake.png|thumb|right|250px|The region around the [[comet nucleus|nucleus]] of Comet Hyakutake, as seen by the [[Hubble Space Telescope]]. Some fragments can be seen breaking off.]]

Radar results from the [[Arecibo Observatory]] indicated that the [[comet nucleus]] was about {{cvt|4.8|km|0}} across, and surrounded by a flurry of pebble-sized particles ejected at a few metres per second. This size measurement corresponded well with indirect estimates using [[infrared]] emission and radio observations.{{r|Sarmecanic_1997|Lisse_1999}}

The small size of the nucleus ([[Halley's Comet]] is about {{cvt|15|km}} across, while Comet Hale–Bopp was about {{cvt|60|km}} across) implies that Hyakutake must have been very active to become as bright as it did. Most comets undergo outgassing from a small proportion of their surface, but most or all of Hyakutake's surface seemed to have been active. The dust production rate was estimated to be about 2{{E|3}}&nbsp;kg/s at the beginning of March, rising to 3{{E|4}}&nbsp;kg/s as the comet approached perihelion. During the same period, dust ejection velocities increased from 50&nbsp;m/s to 500&nbsp;m/s.{{r|Fulle_1997|Jewitt_1997}}

Observations of material being ejected from the nucleus allowed astronomers to establish its rotation period. As the comet passed the Earth, a large puff or blob of material was observed being ejected in the sunward direction every 6.23&nbsp;hours. A second smaller ejection with the same period confirmed this as the rotation period of the nucleus.{{r|Schleicher_1998}}

== See also ==
* [[Lists of comets]]

== Notes ==
{{Refbegin}}
<ol type="a">

<li>{{Note_label|A|a|none}} Solution using the Solar System [[Center of mass#Barycenter in astrophysics and astronomy|Barycenter]]. For objects at such high eccentricity, the Sun's [[Barycentric coordinates (astronomy)|barycentric coordinates]] are more stable than heliocentric coordinates.</li>

</ol>
{{Refend}}

== References ==
{{Reflist|refs=

<ref name="Aguirre_1996">{{cite web
| author1= E. L. Aguirre
| title= How Yuji Hyakutake Found His Comet
| url= http://www.skyandtelescope.com/observing/objects/comets/3304291.html?page=1&c=y
| website= [[Sky & Telescope]]
| access-date= 21 April 2008
| archive-date= 3 February 2009
| archive-url= https://web.archive.org/web/20090203005926/http://www.skyandtelescope.com/observing/objects/comets/3304291.html?page=1&c=y
| url-status= dead }}
</ref>

<ref name="Baalke_1996">{{cite web
| author1= R. Baalke
| title= Comet C/1996 B2 Hyakutake
| url= http://www2.jpl.nasa.gov/comet/hyakutake/index.html
| publisher= [[NASA]] / [[Jet Propulsion Laboratory|JPL]]
| date= 24 March 1996
| access-date= 9 January 2007
| archive-date= 6 January 2011
| archive-url= https://web.archive.org/web/20110106160112/http://www2.jpl.nasa.gov/comet/hyakutake/index.html
| url-status= dead }}
</ref>

<ref name="barycenter">{{cite web  
| author1= Horizons output 
| author1-link= JPL Horizons On-Line Ephemeris System 
| url= http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=C/1996+B2 
| title= Barycentric Osculating Orbital Elements for Comet Hyakutake (C/1996 B2)
| date= 30 January 2011
| access-date= 31 January 2011
| archive-url= https://web.archive.org/web/20190605225109/https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=C%2F1996+B2 
 | archive-date= 5 June 2019 }}
</ref>

<ref name="Bockelée-Morvan_1998">{{cite journal
| author1= D. Bockelée-Morvan
| author2= D. Gautier
| author3= D. C. Lis
| author4= K. Young
| author5= J. Keene
| author6= T. Phillips
| author7= T. Owen
| author8= J. Crovisier
| author9= P. F. Goldsmith
| author10= E. A. Bergin
| author11= D. Despois
| author12= A. Wootten
| display-authors= 5
| title= Deuterated Water in Comet C/1996 B2 (Hyakutake) and Its Implications for the Origin of Comets
| url= https://ntrs.nasa.gov/api/citations/19980035143/downloads/19980035143.pdf
| journal= [[Icarus (journal)|Icarus]] 
| year= 1998
| volume= 133
| issue= 1
| pages= 147–162
| bibcode= 1998Icar..133..147B
| s2cid= 121830932
| doi= 10.1006/icar.1998.5916
| hdl= 2060/19980035143
| hdl-access= free }}
</ref>

<ref name="Cravens_2002">{{cite journal
| author1= T. E. Cravens
| title= X-ray Emission from Comets
| journal= [[Science (journal)|Science]]
| volume= 296
| issue= 5570
| pages=1042–1046
| year= 2002
| bibcode= 2002Sci...296.1042C
| s2cid= 26407069
| pmid=12004110
| doi= 10.1126/science.1070001 }}
</ref>

<ref name="ESO_1996">{{cite web
| title= Comet Hyakutake to Approach the Earth in Late March 1996
| url= https://www.eso.org/public/news/eso9613/
| publisher= [[European Southern Observatory]]
| date= 16 February 1996
| access-date= 8 February 2023 }}
</ref>

<ref name="ESO_2009">{{cite web
| title= Comet Hyakutake: Orbital elements and 10-day ephemeris 
| url= http://www.eso.org/public/events/astro-evt/hyakutake/eph/comet-hyakutake-eph-may23-bm.txt
| publisher= [[European Southern Observatory]]
| archive-url= https://web.archive.org/web/20090203101107/http://www.eso.org/public/events/astro-evt/hyakutake/eph/comet-hyakutake-eph-may23-bm.txt
| archive-date= 3 February 2009
| url-status= dead }}
</ref>

<ref name="Fulle_1997">{{cite journal
| author1= M. Fulle
| author2= H. Mikuz
| author3= S. Bosio
| title= Dust environment of Comet Hyakutake 1996 B2
| url= https://ui.adsabs.harvard.edu/link_gateway/1997A%26A...324.1197F/ADS_PDF
| journal= Astronomy and Astrophysics
| year= 1997
| volume= 324
| pages= 1197–1205
| bibcode= 1997A&A...324.1197F }}
</ref>

<ref name="Glanz_1996">{{cite journal
| author1= J. Glanz
| title= Comet Hyakutake Blazes in X-rays
| journal= [[Science (journal)|Science]]
| year= 1996
| volume= 272
| issue= 5259
| pages= 194
| bibcode= 1996Sci...272..194G
| s2cid= 120173459
| doi= 10.1126/science.272.5259.194 }}
</ref>

<ref name="Gloeckler_2000">{{cite journal
| author1= G. Gloeckler
| author2= J. Geiss
| author3= N. A. Schwadron
| author4= L. A. Fisk
| author5= T. H. Zurbuchen
| author6= F. M. Ipavich
| author7= R. von Steiger
| author8= H. Balsiger
| author9= B. Wilken
| display-authors= 5
| title= Interception of comet Hyakutake's ion tail at a distance of 500 million kilometres
| url= https://deepblue.lib.umich.edu/bitstream/2027.42/62756/1/404576a0.pdf
| journal= [[Nature (journal)|Nature]]
| year= 2000
| volume= 404
| issue= 6778
| pages= 576–578 
| bibcode= 2000Natur.404..576G
| s2cid= 4420901
| pmid= 10766234
| doi= 10.1038/35007015
| hdl= 2027.42/62756 
| hdl-access= free }}
</ref>

<ref name="harvard1">{{cite press release
| title= Press Information Sheet: Comet C/1996 B2 (Hyakutake)
| url= http://www.cfa.harvard.edu/iau/pressinfo/info1996B2.html
| publisher= Harvard-Smithsonian Center for Astrophysics
| date= 20 November 1996
| access-date= 16 October 2007
| archive-date= 21 November 2007
| archive-url= https://web.archive.org/web/20071121004046/http://www.cfa.harvard.edu/iau/pressinfo/info1996B2.html
| url-status= dead}}
</ref>

<ref name="Hyakutake_1996">{{cite press release
| author1= Y. Hyakutake
| title= Press Statement by Mr. Yuji Hyakutake Discoverer of Comet Hyakutake
| url= http://www2.jpl.nasa.gov/comet/hyakutake/disc2.html
| date= 29 March 1996
| access-date= 13 February 2007
| archive-date= 21 February 2012
| archive-url= https://web.archive.org/web/20120221223141/http://www2.jpl.nasa.gov/comet/hyakutake/disc2.html
| url-status= dead }}
</ref>

<ref name="IAUC_6299">{{cite journal
| author1= D. W. Green
| title= Comet 1996 B2
| url= http://www.cbat.eps.harvard.edu/iauc/06200/06299.html
| journal= Central Bureau for Astronomical Telegrams
| volume= 6299
| date= 31 January 1996 }}
</ref>

<ref name="IAUC_6303">{{cite journal  
| author1= B. G. Marsden
| title= Comet C/1996 B2 (Hyakutake)
| url= http://www.cbat.eps.harvard.edu/iauc/06300/06303.html
| journal= Central Bureau for Astronomical Telegrams
| volume= 6303
| date= 3 February 1996
| page= 1
| bibcode= 1996IAUC.6303....1G }}
</ref>

<ref name="James_1998">{{cite journal
| author1= N. D. James
| title= Comet C/1996 B2 (Hyakutake): The Great Comet of 1996
| url= https://ui.adsabs.harvard.edu/link_gateway/1998JBAA..108..157J/ADS_PDF
| journal= Journal of the British Astronomical Association
| year= 1998
| volume= 108
| pages= 157–171
| bibcode= 1998JBAA..108..157J }}
</ref>

<ref name="Jewitt_1997">{{cite journal 
| author1= D. C. Jewitt
| author2= H. E. Matthews
| title= Submillimeter Continuum Observations of Comet Hyakutake (1996 B2)
| url= https://ui.adsabs.harvard.edu/link_gateway/1997AJ....113.1145J/ADS_PDF
| journal= Astronomical Journal 
| year= 1997
| volume= 113
| pages= 1145 
| bibcode= 1997AJ....113.1145J 
| doi= 10.1086/118333
| doi-access= free }}
</ref>

<ref name="Jones_2000">{{cite journal
| author1= G. H. Jones
| author2= A. Balogh
| author3= T. S. Horbury
| title= Identification of comet Hyakutake's extremely long ion tail from magnetic field signatures
| journal= [[Nature (journal)|Nature]]
| year= 2000
| volume= 404
| issue= 6778
| pages= 574–576
| bibcode= 2000Natur.404..574J
| s2cid= 4418311
| pmid= 10766233
| doi= 10.1038/35007011 }}
</ref>

<ref name="Jones_2002">{{cite conference
| author1= G. H. Jones
| editor1= B. Warmbein
| title= Ulysses's encounters with comet Hyakutake
| url= https://ui.adsabs.harvard.edu/link_gateway/2002ESASP.500..563J/ADS_PDF
| conference= Proceedings of Asteroids, Comets, Meteors - ACM 2002. International Conference
| publisher= ESA Publications Division
| location= Berlin, Germany
| date= 29 July – 2 August 2002
| pages= 563–566 
| isbn= 92-9092-810-7
| bibcode= 2002ESASP.500..563J }}
</ref>

<ref name="Jones_2006">{{cite arXiv
| author1= G. H. Jones
| author2= H. A. Elliott
| author3= D. J. McComas
| author4= M. E. Hill
| author5= J. Vandegriff
| author6= E. J. Smith
| author7= F. J. Crary
| author8= J. H. Waite
| display-authors= 4
| title= Cometary ions detected by the Cassini spacecraft 6.5 au downstream of Comet 153P/Ikeya-Zhang
| eprint= 2006.00500
| year= 2020
| class= astro-ph.EP }}
</ref>

<ref name="jpldata">{{cite web
| title= C/1996 B2 (Hyakutake) – JPL Small-Body Database Lookup 
| url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1996B2
| website= ssd.jpl.nasa.gov
| publisher= [[Jet Propulsion Laboratory]]
| access-date= 24 December 2024 }}
</ref>

<ref name="Knight_2023">{{cite arXiv
| author1= M. M. Knight
| author2= R. Kokotanekova
| author3= N. H. Samarasinha
| title= Physical and Surface Properties of Comet Nuclei from Remote Observations
| year= 2023
| eprint= 2304.09309
| class= astro-ph.EP }}
</ref>

<ref name="Lisse_1996">{{cite journal
| author1= C. M. Lisse
| author2= K. Dennerl
| author3= J. Englhauser
| author4= M. Harden
| author5= F. E. Marshall
| author6= M. J. Mumma
| author7= R. Petre
| author8= J. P. Pye 
| author9= M. J. Ricketts
| author10= J. Schmitt
| author11= J. Trümper
| author12= R. G. West
| display-authors= 5
| title= Discovery of X-ray and Extreme Ultraviolet Emission from Comet C/Hyakutake 1996 B2
| url= https://zenodo.org/records/1231082/files/article.pdf
| journal= Science
| year= 1996
| volume= 274
| issue= 5285
| pages= 205–209
| bibcode= 1996Sci...274..205L
| s2cid= 122700701
| doi= 10.1126/science.274.5285.205 }}
</ref>

<ref name="Lisse_1999">{{cite journal
| author1= C. M. Lisse
| author2= Y. R. Fernández
| author3= A. Kundu
| author4= M. F. A'Hearn
| author5= A. Dayal
| author6= L. K. Deutsch
| author7= G. G. Fazio
| author8= J. L. Hora
| author9= W. F. Hoffmann
| display-authors= 5
| title= The Nucleus of Comet Hyakutake (C/1996 B2)
| journal= [[Icarus (journal)|Icarus]]
| year= 1999
| volume= 140
| issue= 1
| pages= 189–204 
| bibcode= 1999Icar..140..189L 
| doi= 10.1006/icar.1999.6131 }}
</ref>

<ref name="Lisse_2001">{{cite journal
| author1= C. M. Lisse
| author2= D. J. Christian
| author3= K. Dennerl
| author4= K. J. Meech
| author5= R. Petre
| author6= H. A. Weaver
| author7= S. J. Wolk
| display-authors= 4
| title= Charge Exchange-Induced X-Ray Emission from Comet C/1999 S4 (LINEAR)
| journal= [[Science (journal)|Science]]
| year= 2001
| volume= 292
| issue= 5520
| pages= 1343–1348
| bibcode= 2001Sci...292.1343L
| pmid= 11359004
| doi= 10.1126/science.292.5520.1343 }}
</ref>

<ref name="Minter_1996">{{cite journal
| author1= A. H. Minter
| author2= G. Langston
| title= 8.35 and 14.35 GHz continuum observations of comet Hyakutake C/1996 B2
| journal= Astrophysical Journal Letters
| year= 1996
| volume= 467
| issue= 1
| pages=L37–L40
| bibcode = 1996ApJ...467L..37M
| doi= 10.1086/310192
| doi-access= free }}
</ref>

<ref name="Mumma_1996">{{cite journal
| author1= M. J. Mumma
| author2= M. A. Disanti
| author3= N. dello Russo
| author4= M. Fomenkova
| author5= K. Magee-Sauer
| author6= C. D. Kaminski
| author7= D. X. Xie
| display-authors= 4
| title= Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin
| journal= [[Science (journal)|Science]]
| year= 1996
| volume= 272
| issue= 5266
| pages= 1310–1314
| bibcode= 1996Sci...272.1310M
| s2cid= 27362518
| pmid= 8650540
| doi= 10.1126/science.272.5266.1310 }}
</ref>

<ref name="Nakano_2008">{{Cite web
| title= Nakano Note 838 
| url= http://www.oaa.gr.jp/~oaacs/nk/nk838.htm
| access-date= 12 May 2008
| archive-date= 24 July 2011
| archive-url= https://web.archive.org/web/20110724160810/http://www.oaa.gr.jp/~oaacs/nk/nk838.htm
| url-status= live }}
</ref>

<ref name="NOVA_1997">{{cite web
| title= Hale-Bopp and Hyakutake
| url= https://www.pbs.org/wgbh/nova/spacewatch/comets.html
| website= NOVA Online
| year= 1997
| access-date= 8 February 2023 }}
</ref>

<ref name="physicsworld1">{{cite news
| title= Comet Hyakutake makes a mark on ''Ulysses''
| url= https://physicsworld.com/a/comet-hyakutake-makes-a-mark-on-ulysses/
| website= PhysicsWorld
| date= 6 April 2000
| access-date= 10 November 2020
| archive-date= 9 November 2020
| archive-url= https://web.archive.org/web/20201109190833/https://physicsworld.com/a/comet-hyakutake-makes-a-mark-on-ulysses/
| url-status= live }}
</ref>

<ref name="Sarmecanic_1997">{{cite journal
| author1= J. Sarmecanic
| author2= M. Fomenkova
| author3= B. Jones
| author4= T. Lavezzi
| title= Constraints on the Nucleus and Dust Properties from Mid-Infrared Imaging of Comet Hyakutake
| journal= Astrophysical Journal Letters
| year= 1997
| volume= 483
| issue= 1
| pages= L69–L72 
| bibcode= 1997ApJ...483L..69S 
| pmid= 11541247
| s2cid= 24944390
| doi= 10.1086/310726
| doi-access= free }}
</ref>

<ref name="Schleicher_1998">{{cite journal
| author1= D. G. Schleicher
| author2= R. L. Millis
| author3= D. J. Osip
| author4= S. M. Lederer 
| title= Activity and the Rotation Period of Comet Hyakutake (1996 B2)
| journal= [[Icarus (journal)|Icarus]]
| year= 1998
| volume= 131
| issue= 2
| pages= 233–244 
| bibcode= 1998Icar..131..233S 
| doi= 10.1006/icar.1997.5881 }}
</ref>

<ref name="Skartlien_1996">{{cite web
| author1= R. Skartlien
| title= Skartlien Images of Comet 1996 B2 Hyakutake
| url= https://www2.jpl.nasa.gov/comet/hyakutake/skar3.html
| publisher= [[NASA]] / [[Jet Propulsion Laboratory|JPL]]
| date= 27 March 1996
| access-date= 8 February 2023
| archive-date= 28 April 1999
| archive-url= https://web.archive.org/web/19990428103313/https://www2.jpl.nasa.gov/comet/hyakutake/skar3.html
| url-status= dead }}
</ref>

<ref name="skyguide1">{{cite book
| author1= Astronomical Society of Southern Africa
| title= Sky Guide Africa South – 2020
| url= https://books.google.com/books?id=PXW7DwAAQBAJ&pg=PT156
| publisher=Penguin Random House South Africa
| year= 2019
| isbn= 978-1-775-84667-3 }}
</ref>

<ref name="Sosa_2011">{{cite journal
| author1= A. Sosa
| author2= J. A. Fernández
| title= Masses of long-period comets derived from non-gravitational effects
| url= https://academic.oup.com/mnras/article-pdf/416/1/767/4051800/mnras0416-0767.pdf
| journal= Monthly Notices of the Royal Astronomical Society
| year= 2011
| volume= 416
| issue= 1
| pages= 767–782
| doi= 10.1111/j.1365-2966.2011.19111.x
| doi-access= free }}
</ref>

<ref name="Tenmon_1996">{{cite web
| author1= G. Tenmon
| author2= Y. Hyakutake
| translator1= M. Okamoto
| title= How Comet Hyakutake B2 Was Discovered
| url= http://www2.jpl.nasa.gov/comet/hyakutake/disc1.html
| publisher= [[NASA]]
| date= April 1996
| access-date= 9 January 2007
| archive-date= 12 June 2011
| archive-url= https://web.archive.org/web/20110612043748/http://www2.jpl.nasa.gov/comet/hyakutake/disc1.html
| url-status= dead
| language= ja }}
</ref>

<ref name="Whipple_1978">{{cite journal
| author1= F. L. Whipple
| title= Cometary Brightness Variation and Nucleus Structure (Paper dedicated to Professor Hannes Alfvén on the occasion of his 70th birthday, 30 May 1978.)
| url= https://link.springer.com/content/pdf/10.1007/BF00896489.pdf
| journal= The Moon and the Planets
| year= 1978
| volume= 18
| issue= 3
| pages= 343–359 
| bibcode= 1978M&P....18..343W
| s2cid= 122368212
| doi= 10.1007/BF00896489
| doi-access= free }}
</ref>

}}

==Further reading==
{{Div col|small=yes}}
*{{cite journal
 | title=Prompt Emission by OH in Comet Hyakutake
 | last1=A'Hearn | first1=Michael F. | last2=Krishna Swamy | first2=K. S.
 | last3=Wellnitz | first3=Dennis D. | last4=Meier | first4=Roland
 | journal=The Astronomical Journal
 | volume=150 | issue=1 | id=5 | date=July 2015
 | page=5 | doi=10.1088/0004-6256/150/1/5 | bibcode=2015AJ....150....5A | s2cid=124705048 }}
*{{cite conference
 | title=λ4430 Emission by Comet Hyakutake
 | last1=A'Hearn | first1=M. F. | last2=Wellnitz | first2=D. D.
 | last3=Meier | first3=R.
 | conference=The Diffuse Interstellar Bands, Proceedings of the International Astronomical Union, IAU Symposium
 | volume=297 | pages=216–218
 | date=February 2014
 | doi=10.1017/S1743921313015883 | bibcode=2014IAUS..297..216A | doi-access=free }}
*{{cite journal
 | title=Aggregate dust model to study the polarization properties of comet C/1996 B2 Hyakutake
 | last1=Das | first1=Himadri Sekhar | last2=Suklabaidya | first2=Abinash
 | last3=Majumder | first3=Saonli Datta | last4=Sen | first4=Asoke Kumar
 | journal=Research in Astronomy and Astrophysics
 | volume=10 | issue=4 | pages=355–362
 | date=April 2010 | doi=10.1088/1674-4527/10/4/006 
 | arxiv=1001.0633 | bibcode=2010RAA....10..355D | s2cid=250693899 }}
*{{cite journal
 | title=Large Aperture O I 6300 Å Observations of Comet Hyakutake: Implications for the Photochemistry of OH and O I Production in Comet Hale-Bopp
 | last1=Morgenthaler | first1=Jeffrey P. | last2=Harris | first2=Walter M.
 | last3=Combi | first3=Michael R.
 | journal=The Astrophysical Journal
 | volume=657 | issue=2 | pages=1162–1171 | date=March 2007
 | doi=10.1086/511062 | bibcode=2007ApJ...657.1162M | s2cid=54720494 | doi-access=free }}
*{{cite journal
 | title=Temporal deconvolution of the hydrogen coma. II. Pre- and post-perihelion activity of Comet Hyakutake (1996 B2)
 | last1=Combi | first1=M. R. | last2=Mäkinen | first2=J. T. T.
 | last3=Bertaux | first3=J. -L. | last4=Quemérais | first4=E.
 | journal=Icarus | volume=177 | issue=1 | pages=228–245 | date=September 2005
 | doi=10.1016/j.icarus.2005.03.007 | bibcode=2005Icar..177..228C }}
*{{cite journal
 | title=Comet Hyakutake (C/1996 B2): Spectacular disconnection event and the latitudinal structure of the solar wind
 | last1=Snow | first1=M. | last2=Brandt | first2=J. C.
 | last3=Yi | first3=Y. | last4=Petersen | first4=C. C.
 | last5=Mikuz | first5=H.
 | journal=Planetary and Space Science
 | volume=52 | issue=4 | pages=313–323 | date=March 2004
 | doi=10.1016/j.pss.2003.10.001 | bibcode=2004P&SS...52..313S }}
*{{cite journal
 | title=The rotational structure of the B-X system of sulfur dimers in the spectra of Comet Hyakutake (C/1996 B2)
 | last1=Kim | first1=Sang J. | last2=A'Hearn | first2=M. F.
 | last3=Wellnitz | first3=D. D. | last4=Meier | first4=R.
 | last5=Lee | first5=Y. S. | date=November 2003
 | journal=Icarus | volume=166 | issue=1 | pages=157–166
 | doi=10.1016/j.icarus.2003.07.003 | bibcode=2003Icar..166..157K }}
*{{cite journal
 | title=Analyses of dust coma morphology of Comet Hyakutake (1996 B2) near perigee: outburst behavior, jet motion, source region locations, and nucleus pole orientation
 | last1=Schleicher | first1=David G. | last2=Woodney | first2=Laura M.
 | journal=Icarus | volume=162 | issue=1 | pages=190–213 | date=March 2003
 | doi=10.1016/S0019-1035(02)00054-4 | bibcode=2003Icar..162..190S }}
*{{cite journal
 | title=Hydrogen cyanide in comet C/1996 B2 Hyakutake
 | last1=Magee-Sauer | first1=Karen | last2=Mumma | first2=Michael J.
 | last3=DiSanti | first3=Michael A. | last4=Dello Russo | first4=Neil
 | journal=Journal of Geophysical Research: Planets
 | volume=107 | issue=E11 | id=5096 | date=November 2002
 | page=5096 | doi=10.1029/2002JE001863 | bibcode=2002JGRE..107.5096M }}
*{{cite journal
 | title=Production of ethane and water in comet C/1996 B2 Hyakutake
 | last1=Dello Russo | first1=Neil | last2=Mumma | first2=Michael J.
 | last3=DiSanti | first3=Michael A. | last4=Magee-Sauer | first4=Karen
 | journal=Journal of Geophysical Research: Planets
 | volume=107 | issue=E11 | id=5095 | date=November 2002
 | page=5095 | doi=10.1029/2001JE001838 | bibcode=2002JGRE..107.5095D }}
*{{cite conference
 | title=Comet Hyakutake: thermal evolution model
 | last1=de Sanctis | first1=M. C. | last2=Capria | first2=M. T.
 | last3=Coradini | first3=A.
 | conference=Proceedings of Asteroids, Comets, Meteors – ACM 2002. International Conference, 29 July – 2 August 2002, Berlin, Germany
 | editor-first=Barbara | editor-last=Warmbein
 | location=Noordwijk, Netherlands
 | publisher=ESA Publications Division
 | isbn=92-9092-810-7 | pages=669–672
 | date=November 2002 | bibcode=2002ESASP.500..669D }}
*{{cite conference
 | title=The evolution of the fragments emitted from comet Hyakutake
 | last1=Capria | first1=M. T. | last2=Tozzi | first2=G. P.
 | last3=Coradini | first3=A. | last4=de Sanctis | first4=M. C.
 | conference=Proceedings of Asteroids, Comets, Meteors – ACM 2002. International Conference, 29 July – 2 August 2002, Berlin, Germany
 | editor-first=Barbara | editor-last=Warmbein
 | location=Noordwijk, Netherlands
 | publisher=ESA Publications Division
 | isbn=92-9092-810-7 | pages=653–656
 | date=November 2002 | bibcode=2002ESASP.500..653C }}
*{{cite conference
 | title=Modelling of non-gravitational motion of comet C/1996 B2 Hyakutake
 | last1=Szutowicz | first1=Slawomira | last2=Królikowska | first2=Malgorzata
 | last3=Sitarski | first3=Grzegorz
 | conference=Proceedings of Asteroids, Comets, Meteors – ACM 2002. International Conference, 29 July – 2 August 2002, Berlin, Germany
 | editor-first=Barbara | editor-last=Warmbein
 | location=Noordwijk, Netherlands
 | publisher=ESA Publications Division
 | isbn=92-9092-810-7 | pages=633–636
 | date=November 2002 | bibcode=2002ESASP.500..633S }}
*{{cite journal
 | title=Long- and Short-Term Photometric Behavior of Comet Hyakutake (1996 B2)
 | last1=Schleicher | first1=David G. | last2=Osip | first2=David J.
 | journal=Icarus | volume=159 | issue=1 | pages=210–233 | date=September 2002 
 | doi=10.1006/icar.2002.6875 | bibcode=2002Icar..159..210S }}
*{{cite journal
 | title=Spectroscopy of Comet Hyakutake at 80–700 Å: First Detection of Solar Wind Charge Transfer Emissions
 | last1=Krasnopolsky | first1=Vladimir A. | last2=Mumma | first2=Michael J.
 | journal=The Astrophysical Journal
 | volume=549 | issue=1 | pages=629–634 | date=March 2001
 | doi=10.1086/319064 | bibcode=2001ApJ...549..629K | s2cid=122972759 | doi-access=free }}
{{Div col end}}

== External links ==
{{Commons category}}
* [http://www.jpl.nasa.gov/comet/hyakutake/ JPL Comet Hyakutake home page] {{Webarchive|url=https://web.archive.org/web/20180922203043/https://www2.jpl.nasa.gov/comet/hyakutake/ |date=22 September 2018 }}
* [https://web.archive.org/web/20080906174837/http://ssd.jpl.nasa.gov/data/ELEMENTS.COMET JPL DASTCOM Cometary Orbital Elements]
* [http://www.cometography.com/lcomets/1996b2.html Cometography.com: Comet Hyakutake]
* {{APOD |date=14 March 1996 |title=Diagram of Comet Hyakutake's orbit}}
* [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=C/1996 B2|id=1000131}}

{{Comets}}
{{Portal bar|Astronomy|Stars|Spaceflight|Outer space|Solar System}}
{{Authority control}}
{{Featured article}}

{{DEFAULTSORT:Hyakutake, 1996 B2}}
[[Category:Non-periodic comets]]
[[Category:Science and technology in Japan]]
[[Category:Astronomical objects discovered in 1996|19960131]]
[[Category:Great comets]]
[[Category:Near-Earth comets]]
[[Category:Discoveries by Yuji Hyakutake]]
[[Category:Discoveries by amateur astronomers]]