View source for Comet Encke

{{short description|Periodic comet}}
{{Use dmy dates|date=October 2025}}
{{Infobox comet
| name            = 2P/Encke
| image           = Comet Encke.jpg
| caption         = Comet Encke photographed from the [[Kitt Peak Observatory]] on 5 January 1994.
| discoverer      = {{unbulleted|[[Pierre Méchain]]|[[Johann Franz Encke]]|{{small|(recognition of periodicity)}}}}
| discovery_date  = 17 January 1786
| mpc_name        = {{unbulleted|P/1786 B1, P/1795 V1|P/1805 U1, P/1818 W1|P/1822 L1}}
| designations    = {{unbulleted|1786 I, 1795, 1805|1819 I, 1822 II, 1825 III|1829, 1832 I, 1835 II|1838, 1842 I, 1845 IV}}
| orbit_ref       = {{r|jpldata|MPC}}
| epoch           = 5 May 2025 ([[Julian day|JD]] 2460800.5)
| observation_arc = 239.45 years
| obs             = 6,016
| perihelion      = 0.339 AU
| aphelion        = 4.097 AU
| semimajor       = 2.218 AU
| eccentricity    = 0.84711
| period          = 3.304 years
| max_speed       = {{cvt|69.5|km/s|km/h}}{{r|Horizons2023}}
| inclination     = 11.344°
| asc_node        = 334.01°
| arg_peri        = 187.28°
| mean            = 167.19°
| tjup            = 3.022
| Earth_moid      = 0.168 AU
| Jupiter_moid    = 0.907 AU
| physical_ref    = 
| mean_diameter   = {{cvt|4.86|km|mi}}{{r|Boehnhardt_2008|Knight_2023}}
| spectral_type   = (V–R) {{=}} {{val|0.44|0.06}}{{r|Lowry_2007}}
| albedo          = 0.046
| rotation        = {{val|11.083|0.003}} hours{{r|Lowry_2007}}
| M1              = 15.6
| M2              = 
| last_p          = 22 October 2023{{r|Yoshida}}
| next_p          = 10 February 2027{{r|Yoshida|Horizons2027}}
}}

'''Comet Encke''' {{IPAc-en|'|E|N|k|i}}, or '''Encke's Comet''' (official designation: '''2P/Encke'''), is a [[periodic comet]] that completes an orbit of the [[Sun]] once every 3.3 years. (This is the shortest period of a reasonably bright comet; the faint [[main-belt comet]] [[311P/PanSTARRS]] has a period of 3.2 years.) Encke was first recorded by [[Pierre Méchain]] on 17 January 1786,{{r|Marsden_1974}} but it was not recognized as a periodic comet until 1819 when its orbit was computed by [[Johann Franz Encke]]. Like [[Halley's Comet]], it is unusual in its being named after the calculator of its orbit rather than its discoverer. Like most comets, it has a very low [[albedo]], reflecting only 4.6% of the light its [[comet nucleus|nucleus]] receives, although comets generate a large [[coma (cometary)|coma]] and tail that can make them much more visible during their [[perihelion]] (closest approach to the Sun). The diameter of the nucleus of Encke's Comet is {{cvt|4.86|km|mi}}.{{r|Boehnhardt_2008}}

== Discovery ==
As its official designation implies, Encke's Comet was the first periodic comet discovered after [[Halley's Comet]] (designated 1P/Halley). It was independently observed by several astronomers, the first two being [[Pierre Méchain]] and [[Charles Messier]] in 1786.{{r|Marsden_1974}} It was next observed by [[Caroline Herschel]] in 1795{{r|Herschel_1876}} and was "discovered" for a third time by [[Jean-Louis Pons]] in 1818.<ref name=book/> Its orbit was calculated by [[Johann Franz Encke]], who through laborious calculations was able to link observations of comets in 1786 (designated 2P/1786 B1), 1795 (2P/1795 V1), 1805 (2P/1805 U1) and 1818 (2P/1818 W1) to the same object. In 1819 he published his conclusions in the journal ''Correspondance astronomique'', and predicted correctly its return in 1822 (2P/1822 L1). It was recovered by [[Carl Ludwig Christian Rümker]] at [[Parramatta Observatory]] on 2 June 1822.<ref name=Kronk2/>

== Orbit ==
Comets are in unstable orbits that evolve over time due to [[Perturbation (astronomy)|perturbations]] and [[outgassing]]. Given Encke's low [[orbital inclination]] near the [[Ecliptic#Ecliptic and planets|ecliptic]] and brief [[orbital period]] of 3 years, the orbit of Encke is frequently perturbed by the inner planets.{{r|jpldata}} Encke is currently close to a 7:2 [[mean motion resonance]] with [[Jupiter]], and it is possible that some of the larger fragments shed by the comet, or released by a larger progenitor of the comet, are trapped in this resonance.{{r|Clark_2019}}

Encke's orbit gets as close as {{convert|0.173|AU|e6km e6mi|abbr=unit}} to Earth ([[minimum orbit intersection distance]]).{{r|jpldata}} On 4 July 1997, Encke passed {{convert|0.19|AU|e6km e6mi|abbr=unit}} from Earth, and on 29 June 2172, it will make a close approach of roughly {{convert|0.1735|AU|e6km e6mi|abbr=unit}}.{{r|jpldata}} On 18 November 2013, it passed {{convert|0.02496|AU|e6km e6mi|abbr=unit}} from Mercury.{{r|jpldata}} Close approaches to Earth usually occur every 33 years.

Comet Encke has a [[perihelion]] (closest approach to the Sun) of {{convert|0.34|AU|e6km e6mi|abbr=unit}}, and at perihelion Comet Encke [[Orbital speed#Planets|passes the Sun]] at {{cvt|69.5|km/s|km/h}}.<ref name="Horizons2023"/> Between 1769 and 2103, Comet Encke's perihelion distance only varies from 0.330 AU (in 2050) and 0.347 AU (in 1782).<ref name="kinoshita"/> Of the [[List of numbered comets|numbered comets]] less than 321P, only [[96P/Machholz]] gets closer to the Sun.

== Observations ==
The comet has been observed at every perihelion since 1818 except 1944.{{r|Marsden_1974|Space.com1}}

An attempt to photograph the comet close to aphelion was made on 2 July 1913 using the [[Mount Wilson Observatory#60-inch telescope|Mount Wilson 60-inch telescope]] but the resulting photographic plate was lost in the mail.{{r|Barnard_1914}} A second attempt using the same telescope was made on 1 September 1913 and this showed an object in about the right position (1.5 [[arcminutes]] from its then predicted position) but orbital uncertainties made it impossible to be sure of its identity.{{r|Barnard_1914|Marsden_1974}} A recalculation of Encke's orbit in the 1970s resulted in a calculated position only a few arcseconds (2.0 in ascension and 4.6 in declination) from the imaged object meaning the object probably was Encke.{{r|Marsden_1974}}

In March 1918 the [[Greenwich 28 inch refractor|Greenwich 28-inch]] aperture telescope took observations of Encke (1917c).<ref name=":5"/>

An observer of Encke's in March 1918 had this to say of the comet on March 12, comparing to the early March 9 observation, "The comet much shaper, brighter, smaller; its diameter was 1 1/2', magnitude 7<sup>.</sup>7 (B.D. scale). Its magnitude in the 6-inch Corbett was almost stellar, but in the 28 inch no definitive nucleus could be seen."<ref name=":5"/>

A number of attempts were made to image the comet around the aphelion of 3 September 1972.{{r|Bouška_1972}}<ref name=Kronk/> [[Elizabeth Roemer]] and G. McCorkle photographed the comet on 15 August.{{r|Bouška_1972}} R.E. McCrosky and C.-Y. Shao photographed it on 5 September and Elizabeth Roemer this time with M.R. Gonzales photographed the comet on 13 September.{{r|Bouška_1972}}

In 1980, Encke became the first comet to be detected by radar, which was conducted from the [[Arecibo Observatory]] to measure the size of its nucleus.{{r|Kamoun_1982|Harmon_2005}}

In April 1984 the [[Pioneer Venus Orbiter]] observed the comet in ultra-violet and made measurements of its rate of water loss.{{r|Ulivi_2007}}

[[File:Encke tail rip off.ogg|thumb|left|Encke's Comet loses its tail]]
On 20 April 2007, [[STEREO-A]] observed the tail of Comet Encke to be temporarily torn off by magnetic field disturbances caused by a [[coronal mass ejection]] (a blast of solar particles from the Sun).<ref name="CME2007"/> The tail grew back due to the continuous shedding of dust and gas by the comet.<ref name=APOD/>

== Exploration ==
[[File:Contour comet.jpg|thumb|right|Artist's impression of the ''[[CONTOUR]]'' spacecraft making a flyby of a comet.]]
NASA’s failed ''[[CONTOUR|Comet Nucleus Tour]]'' (CONTOUR) mission was planned to perform a flyby of Encke in November 2003, however it was destroyed shortly after sending itself into an interplanetary trajectory in August 2002.{{r|Portree_2013}}

=== Proposed missions ===
In the 1970s, the [[Goddard Space Flight Centre]] and [[Jet Propulsion Laboratory]] proposed to NASA probes that would fly past the comet in 1980.{{r|Portree_2013}} The Goddard Space Flight Centre's proposal was for a pair of probes launched directly towards the comet while the Jet Propulsion Laboratory plan was to use solar electric propulsion,{{r|Bender_1973}} or a [[Pioneer Venus Orbiter|''Pioneer'']]-class spacecraft.{{r|Jaffe_1974}} NASA did not attempt either mission.{{r|Portree_2013}}

Across the globe, the German [[German Aerospace Center|DLR]] also proposed a mission towards Encke using a spacecraft derived from the [[Helios (spacecraft)|''Helios'']] probes.{{r|Calder_1992}} However, like the NASA proposals, this mission was also not attempted.

== Meteor showers ==
[[File:Ssc2005-04a.jpg|left|thumb|A [[Spitzer Space Telescope|Spitzer]] image of Encke and its debris trail in [[infrared]] light]]
Comet Encke is believed to be the originator of several related [[meteor shower]]s known as the [[Taurids]] (which are encountered as the Northern and Southern Taurids across November, and the [[Beta Taurids]] in late June and early July).<ref>[[Fred Whipple|Whipple]], 1940; Klačka, 1999).</ref> A shower has similarly been reported affecting Mercury.{{r|Killen_2014}}

The near-Earth asteroid {{mpl|(828534) 2004 TG|10}} is likely an inactive fragment of Encke that broke off the comet about 4,000–4,500 years ago.{{r|Porubčan_2006}}

=== Mercury ===
Measurements on board the NASA satellite ''[[MESSENGER]]'' have revealed Encke may contribute to seasonal meteor showers on Mercury. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument discovered seasonal surges of calcium since the probe began orbiting the planet in March 2011. The spikes in calcium levels are thought to originate from small dust particles hitting the planet and knocking calcium-bearing molecules into the atmosphere in a process called impact vaporization. However, the general background of interplanetary dust in the inner Solar System cannot, by itself, account for the periodic spikes in calcium. This suggests a periodic source of additional dust, for example, a cometary debris field.{{r|scinews1}}

== Effects on Earth ==
More than one theory has associated Encke's Comet with impacts of cometary material on Earth, and with cultural significance.

The [[Tunguska event]] of 1908 may have been caused by the impact of a cometary body and has also been postulated by Slovak astronomer [[Ľubor Kresák]] as possibly caused by a fragment of Comet Encke.{{r|Kresak_1978}}

[[File:Hansilk2.png|thumb|350px|right|A Han Dynasty silk comet atlas, featuring drawings of comets believed by Victor Clube and Bill Napier to be related to the breakup of Encke's Comet in the past]]
A theory holds that the ancient symbol of the [[swastika]] appeared in a variety of cultures across the world at a similar time, and could have been inspired by the appearance of a comet from head on, as the curved jets would be reminiscent of the swastika shape (see [[Swastika#Comet|Comets and the swastika motif]]). Comet Encke has sometimes been identified as the comet in question. In their 1982 book ''Cosmic Serpent'' (page 155) [[Victor Clube]] and [[Bill Napier]] reproduce an ancient Chinese catalogue of cometary shapes from the [[Mawangdui Silk Texts]], which includes a swastika-shaped comet, and suggest that some comet drawings were related to the breakup of the progenitor of Encke and the [[Taurid]] meteoroid stream. [[Fred Whipple]] in his ''The Mystery of Comets'' (1985, page 163) points out that Comet Encke's polar axis is only 5 degrees from its orbital plane: such an orientation is ideal to have presented a pinwheel like aspect to our ancestors when Encke was more active.

Astronomers planned a 2019 search campaign for fragments of comet Encke which would have been visible from Earth as the Taurid swarm passed between July 5–11, and July 21 – August 10.<ref name="Plait"/> There were no reports of discoveries of any such objects.

== Importance in the scientific history of luminiferous aether ==
Comet Encke (and [[Biela's Comet]]) had a role in [[History of science|scientific history]] in the generally discredited concept of ''[[luminiferous aether]]''. As its orbit was perturbed and shortened, the shortening could only be ascribed to the [[Drag (physics)|drag]] of an "ether" through which it orbited in [[outer space]]. A 1860 school manual for example reads:

:Astronomy furnishes evidence of the presence in space of a medium resisting the motion of the heavenly bodies. Encke's comet is found to lose about two days in each successive period of 1,200 days. Biela's comet, with twice that length of period, loses about one day. That is, the successive returns of these bodies is found to be accelerated by this amount. No other cause for this irregularity has been found but the agency of the supposed ether.<ref>{{Cite web|url=https://archive.org/stream/firstprinciples06sillgoog/firstprinciples06sillgoog_djvu.txt|title=First principles of chemistry, for the use of colleges and schools|year=1860|publisher=Philadelphia, H. C. Peck & T. Bliss}}</ref>

Encke's pole tumbles in an 81-year period, therefore it will accelerate for half that time, and decelerate for the other half of the time (since the orientation of the comets rotation to solar heating determines how its orbit changes due to outgassing forward or aft of the comet's course). The authors of this 1860 textbook of course could not know that the pole of the comet would tumble as it does over such a long period of time, or that outgassing would induce a thrust to change its course.

The supposed shortening of the orbit of Encke's Comet demonstrating the existence of ether was mentioned in Edgar Alen Poe's story, "The Unparalleled Adventures Of One Hans Pfaall".

== Gallery ==
<gallery>
File:Comet Encke from MESSENGER.png|A ''[[MESSENGER]]'' image of Comet Encke at its closest approach to [[Mercury (planet)|Mercury]], 17/11/2013<ref>{{cite web |url=http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?image_id=1303 |title=MESSENGER: MErcury Surface, Space ENvironment, GEochemistry, and Ranging |access-date=2014-03-28 |url-status=dead |archive-url=https://web.archive.org/web/20131205110226/http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?image_id=1303 |archive-date=2013-12-05 }}</ref> (NASA/JHUAPL/Carnegie Institution of Washington)
</gallery>

== References ==
=== Citations ===
{{Reflist|refs=

<ref name="Barnard_1914">{{cite journal
| author1= E. E. Barnard
| title= Encke's Comet. On the Possibility of Photographing the Comet at all Points in its Orbit
| journal= Popular Astronomy
| year= 1914
| volume= 22
| issue= 10
| pages= 607–610
| bibcode= 1914PA.....22..607B }}
</ref>

<ref name="Bender_1973">{{cite report
| author1= D. F. Bender
| author2= K. L. Atkins
| author3= C. C. Sauer Jr.
| title= Mission design for a 1980 Encke slow flyby using solar electric propulsion
| url= https://ntrs.nasa.gov/citations/19740034833
| publisher= [[NASA]] / [[JPL]]
| year= 1973
| id= AAS PAPER 73-204 }}
</ref>

<ref name="Boehnhardt_2008">{{cite journal
| author1= H. Boehnhardt
| author2= G. P. Tozzi
| author3= S. Bagnulo
| author4= K. Muinonen
| author5= A. Nathues
| author6= L. Kolokolova
| display-authors= 3
| title= Photometry and polarimetry of the nucleus of comet 2P/Encke
| url= https://www.aanda.org/articles/aa/pdf/2008/39/aa09922-08.pdf
| journal= Astronomy & Astrophysics
| year= 2008
| volume= 489
| issue= 3
| pages= 1337–1343
| bibcode= 2008A&A...489.1337B
| arxiv= 0809.1959
| doi= 10.1051/0004-6361:200809922
| doi-access= free }}
</ref>

<ref name="Bouška_1972">{{cite journal
| author1= J. Bouška
| author2= V. Vanýsek
| title= A Note on the Cometary Nucleus
| url= https://dml.cz/bitstream/handle/10338.dmlcz/142282/ActaCarolinae_013-1972-2_8.pdf
| journal= Acta Universitatis Carolinae. Mathematica et Physica 
| year= 1972
| volume= 13
| issue= 2
| pages= 73–84
| bibcode= 1972AcMPh..13...73B }}
</ref>

<ref name="Calder_1992">{{cite book
| author1= N. Calder
| title= Giotto to the Comets
| publisher= Presswork
| location= London
| year= 1992
| page= 21
| isbn= 0-9520115-0-6 }}
</ref>

<ref name="Clark_2019">{{cite journal
| author1= D. Clark
| author2= P. Wiegert
| author3= P. G. Brown
| title= The 2019 Taurid resonant swarm: prospects for ground detection of small NEOs
| journal= Monthly Notices of the Royal Astronomical Society
| year= 2019
| volume= 487
| issue= 1
| pages= 35–39
| bibcode= 2019MNRAS.487L..35C
| arxiv= 1905.01260
| doi= 10.1093/mnrasl/slz076
| doi-access= free }}
</ref>

<ref name="Harmon_2005">{{cite journal
| author1= J. K. Harmon
| author2= M. C. Nolan
| title= Radar observations of Comet 2P/Encke during the 2003 apparition
| journal= Icarus
| year= 2005
| volume= 176
| issue= 1
| pages= 175–183 
| bibcode= 2005Icar..176..175H
| doi= 10.1016/j.icarus.2005.01.012 }}
</ref>

<ref name="Herschel_1876">{{cite book
| author1= C. L. Herschel
| editor1= J. Herschel
| title= Memoir and Correspondence of Caroline Herschel
| url= https://archive.org/details/memoircorrespond00hersiala
| publisher= John Murray, Albemarle Street
| location= London
| year= 1876 }}
</ref>

<ref name="Jaffe_1974">{{cite report
| author1= L. D. Jaffe
| author2= C. Elachi
| author3= C. E. Giffin
| author4= W. Huntress
| author5= R. L. Newburn
| author6= R. H. Parker
| author7= F. W. Taylor
| author8= T. E. Thorpe
| display-authors= 4
| title= Science aspects of a 1980 flyby of Comet Encke with a ''Pioneer'' spacecraft
| url= https://ntrs.nasa.gov/api/citations/19760015139/downloads/19760015139.pdf
| publisher= [[NASA]] / [[JPL]]
| year= 1974
| bibcode= 1974jpl..rept.....J }}
</ref>

<ref name="jpldata">{{cite web
| title= 2P/Encke – JPL Small-Body Database Lookup
| url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2P
| website= ssd.jpl.nasa.gov
| publisher= [[Jet Propulsion Laboratory]]
| access-date= 2023-08-08 }}
</ref>

<ref name="Kamoun_1982">{{cite journal
| author1= P. G. Kamoun
| author2= D. B. Campbell
| author3= S. J. Ostro
| author4= G. H. Pettengill
| author5= I. I. Shapiro
| title= Comet Encke: Radar Detection of Nucleus
| journal= Science
| year= 1982
| volume= 216
| issue= 4543
| pages= 293-295
| bibcode= 1982Sci...216..293K
| doi= 10.1126/science.216.4543.293 }}
</ref>

<ref name="Killen_2014">{{cite journal
| author1= R. M. Killen
| author2= J. M. Hahn
| title= Impact Vaporization as a Possible Source of Mercury's Calcium Exosphere
| journal= Icarus
| volume= 250
| pages= 230–237
| year= 2014
| bibcode= 2015Icar..250..230K
| doi= 10.1016/j.icarus.2014.11.035 }}
</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="Kresak_1978">{{cite journal
| author1= L. Kresak
| title= The Tunguska object: A fragment of Comet Encke
| journal= Astronomical Institutes of Czechoslovakia
| year= 1978
| volume= 29
| pages= 129
| bibcode= 1978BAICz..29..129K }}
</ref>

<ref name="Lowry_2007">{{cite journal
| author1= S. C. Lowry
| author2= P. R. Weissman
| title= Rotation and color properties of the nucleus of Comet 2P/Encke
| journal= [[Icarus (journal)|Icarus]]
| year= 2007
| volume= 188
| issue= 1
| pages= 212–223
| bibcode= 2007Icar..188..212L
| arxiv= astro-ph/0612380
| doi= 10.1016/j.icarus.2006.11.014 }}
</ref>

<ref name="Marsden_1974">{{cite journal
| author1= B. G. Marsden
| author2= Z. Sekanina
| title= Comets and nongravitational forces. VI. Periodic Comet Encke 1786-1971
| journal= The Astronomical Journal
| year= 1974
| volume= 9
| issue= 3
| pages= 413–419
| bibcode= 1974AJ.....79..413M
| doi=10.1086/111560
| doi-access= free }}
</ref>

<ref name="MPC">{{cite web
| title= 2P/Encke Orbit
| url= http://www.minorplanetcenter.net/db_search/show_object?object_id=2P
| publisher= [[Minor Planet Center]]
| access-date= 25 July 2025 }}
</ref>

<ref name="Ulivi_2007">{{cite book
| author1= P. Ulivi
| author2= D. M. Harland
| title= Robotic Exploration of the Solar System Part I: The Golden Age 1957–1982
| publisher= Springer
| year= 2007
| pages= 281
| isbn= 978-0-387-49326-8 }}
</ref>

<ref name="Portree_2013">{{cite magazine
| author1= D. S. Portree
| title= Encke in 1980! (1974)
| url= https://www.wired.com/2013/11/encke-in-1980-2/
| magazine= Wired
| publisher= Condé Nast
| date= 12 November 2013
| access-date= 7 January 2024 }}
</ref>

<ref name="Porubčan_2006">{{cite journal
| author1= V. Porubčan
| author2= L. Kornoš
| author3= I. P. Williams
| title= The Taurid complex meteor showers and asteroids
| journal= Contributions of the Astronomical Observatory Skalnaté Pleso
| year= 2006
| volume= 36
| issue=2
| pages= 103–117
| bibcode= 2006CoSka..36..103P
| arxiv= 0905.1639 }}
</ref>

<ref name="scinews1">{{cite web
| author1= R. M. Killen
| author2= J. M. Hahn
| title= Mercury Experiences Seasonal Meteor Showers, Say NASA Scientists
| url= https://www.sci.news/astronomy/science-mercury-seasonal-meteor-showers-02350.html
| website= Sci-News.com
| date= 2014-12-17
| access-date= 2014-12-29 }}
</ref>

<ref name="Space.com1">{{cite web
| author1= J. Rao
| title= 'Old Faithful' Comet Encke Makes Appearance in November Night Sky
| url= https://www.space.com/23561-comet-encke-november-night-sky.html
| website= Space.com
| date= 2013-11-12
| access-date= 2020-07-25 }}
</ref>

<ref name="Yoshida">{{cite web
| author1= S. Yoshida
| title= 2P/Encke
| url= http://www.aerith.net/comet/catalog/0002P/index.html
| website= www.aerith.net
| access-date= 25 July 2025 }}
</ref>











<ref name="kinoshita">[http://jcometobs.web.fc2.com/pcmtn/0002p.htm 2P/Encke past, present and future orbits] by [[Kazuo Kinoshita]]</ref>

<ref name="Horizons2023">{{cite web
  |title=Horizons Batch for 2P/Encke (90000091) on 2023-Oct-22
  |publisher=[[JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |type=Perihelion occurs when rdot flips from negative to positive
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27DES%3D2P%3BCAP%27&START_TIME=%272023-10-15%27&STOP_TIME=%272023-10-31%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719,22%27
  |archive-url=https://web.archive.org/web/20220615101121/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000090%27&START_TIME=%272023-10-15%27&STOP_TIME=%272023-10-31%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27
  |archive-date=2022-06-15
  |url-status=live
  |accessdate=2022-06-15}} (JPL#K204/20 Soln.date: 2022-May-23)</ref>

<ref name="Horizons2027">{{cite web
  |title=Horizons Batch for 2P/Encke (90000091) on 2027-Feb-10
  |publisher=[[JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |type=Perihelion occurs when rdot flips from negative to positive
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27DES%3D2P%3BCAP%27&START_TIME=%272027-02-09%27&STOP_TIME=%272027-02-11%27&STEP_SIZE=%272%20hours%27&QUANTITIES=%2719,22%27
  |accessdate=2025-09-25}} (JPL#K273/4 Soln.date: 2025-Sep-16)</ref>

<ref name=book>{{cite book|title=Biographical Encyclopedia of Astronomers|page=924}}</ref>

<ref name=Kronk2>{{cite web|last1=Kronk|first1=Gary|title=2P/Encke|url=http://cometography.com/pcomets/002p.html|website=Gary W. Kronk's Cometography|access-date=5 July 2014}}</ref>

<ref name=":5">{{Cite journal|date=1918-04-12|title=Observations of Encke's Comet (1917 c.) made with the 28-inch Equatorial at the Royal Observatory, Greenwich|url=https://academic.oup.com/mnras/article/78/6/448/1113052|journal=Monthly Notices of the Royal Astronomical Society|language=en|volume=78|issue=6|pages=448–449|doi=10.1093/mnras/78.6.448|issn=0035-8711|doi-access=free}}</ref>

<ref name =Kronk>{{cite book |last1=Kronk |first1=Gary W |last2=Meyer |first2=Maik |date=2010 |title=Cometography A Catalog of Comets Volume 5: 1960–1982 |publisher=Cambridge University Press |page=287 |isbn=9780521872263}}</ref>

<ref name="CME2007">{{cite web
 |date=2007-10-01
 |title=The Sun Rips Off a Comet's Tail
 |publisher=Science@NASA
 |url=https://science.nasa.gov/headlines/y2007/01oct_encke.htm
 |access-date=2009-10-20
 |archive-url=https://web.archive.org/web/20091104041757/http://science.nasa.gov/headlines/y2007/01oct_encke.htm
 |archive-date=2009-11-04 |url-status=dead }}</ref>

<ref name=APOD>{{Cite APOD |date=3 October 2007 |title=Comet Encke's Tail Ripped Off}}</ref>

<ref name="Plait">{{cite web |title=Could larger space rocks be hiding in the Beta Taurid Meteor stream? We may find out this summer |publisher=Bad Astronomy |author=Phil Plait |url=https://www.syfy.com/syfywire/could-larger-space-rocks-be-hiding-in-the-beta-taurid-meteor-stream-we-may-find-out-this |access-date=2019-05-14|author-link=Phil Plait |date=2019-05-14 }}</ref>

}}

=== Bibliography ===
{{Refbegin|2}}
* Klačka, Jozef (1999). "Meteor Streams of Comet Encke. Taurid Meteor Complex". [https://arxiv.org/abs/astro-ph/9910045 Abstract]
* Whipple, F.L. (1940). "Photographic meteor studies. III. The Taurid shower." ''Proc. Amer. Phil. Soc.,'' '''83''', 711–745.
* Master, S. and Woldai, T. (2004) The UMM Al Binni structure in the Mesopotamian marshlands of Southern Iraq, as a postulated late holocene meteorite impact crater : geological setting and new LANDSAT ETM + and Aster satellite imagery. Johannesburg, University of Witwatersrand, Economic Geology Research Institute (EGRI), 2004. EGRI - HALL : information circular 382, p.&nbsp;21
&nbsp;&nbsp; &nbsp; http://www.itc.nl/library/Papers_2004/tech_rep/woldai_umm.pdf (1.56 MB)
* Master, S. and Woldai, T. (2004) Umm al Binni structure, southern Iraq, as a postulated late holocene meteorite impact crater : new satellite imagery and proposals for future research. Presented at the ICSU workshop : comet - asteroid impacts and human society, Santa Cruz de Tenerife, Canary Islands, Spain, November 27- December 2, 2004. p.&nbsp;20
* Hamacher, D. W. (2005) "The Umm Al Binni Structure and Bronze Age Catastrophes", ''The Artifact: Publications of the El Paso Archaeological Society'', Vol. 43
* Hamacher, D. W. (2006) "Umm al Binni lake: Effects of a possible Holocene bolide impact", ''Astronomical Society of Australia Meeting'' 40, #15
{{Refend}}

== External links ==
{{Commons}}
* {{JPL Small Body|name=2P/Encke|id=1000025}}
* [http://www.minorplanetcenter.net/db_search/show_object?object_id=2P 2P/Encke] at the [[Minor Planet Center]]'s Database
* [http://cometography.com/pcomets/002p.html 2P/Encke] at Gary W. Kronk's ''Cometography''

{{PeriodicComets Navigator|1P/Halley|PageName=2P/Encke|3D/Biela}}
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