1P/Halley

Discovery
Discovered by:	prehistoric; Named after Edmond Halley
Discovery date:	1758 (first predicted perihelion)
Alternate designations:	Halley's Comet, 1P (see Designation below)
Orbital characteristics A
Epoch:	2449400.5 (February 17, 1994)
Aphelion distance:	35.1 AU (December 9, 2023)[1]
Perihelion distance:	0.586 AU
Semi-major axis:	17.8 AU
Eccentricity:	0.967
Orbital period:	75.3 a
Inclination:	162.3°
Last perihelion:	February 9, 1986
Next perihelion (predicted):	July 28, 2061[1]

Halley's Comet, officially designated 1P/Halley and also referred to as Comet Halley after Edmond Halley, is a comet that can be seen every 75–76 years. It is the most famous of all periodic comets. Although in every century many long-period comets appear brighter and more spectacular, Halley is the only short-period comet that is clearly visible to the naked eye, and thus, the only naked-eye comet certain to return within a human lifetime.^[2] Halley's Comet last appeared in the inner Solar System in 1986, and will next appear in mid 2061. This article is about the band. ... Haleys Comet, I Didnt Know and Snootable Snunshine are three unreleased songs written by Richard Wright[1] (aka Nancy Taube) for the band Phish. ... Image File history File links No higher resolution available. ... // Portrait of Edmond Halley painted around 1687 by Thomas Murray (Royal Society, London) Portrait of Edmond Halley Bust of Edmond Halley in the Museum of the Royal Greenwich Observatory Edmond Halley FRS (sometimes Edmund; IPA: ) (November 8, 1656 – January 14, 1742) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist. ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ... This article is about the comet. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... is the 48th day of the year in the Gregorian calendar. ... Year 1994 (MCMXCIV) The year 1994 was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by the United Nations. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... is the 343rd day of the year (344th in leap years) in the Gregorian calendar. ... 2023 (MMXXIII) will be a common year starting on Sunday of the Gregorian calendar. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... The astronomical unit (AU or au or a. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... For the science fiction novella by William Shunn, see Inclination (novella). ... is the 40th day of the year in the Gregorian calendar. ... Year 1986 (MCMLXXXVI) was a common year starting on Wednesday (link displays 1986 Gregorian calendar). ... is the 209th day of the year (210th in leap years) in the Gregorian calendar. ... For the book, see 2061: Odyssey Three. ... // Portrait of Edmond Halley painted around 1687 by Thomas Murray (Royal Society, London) Portrait of Edmond Halley Bust of Edmond Halley in the Museum of the Royal Greenwich Observatory Edmond Halley FRS (sometimes Edmund; IPA: ) (November 8, 1656 – January 14, 1742) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... The following is the IAUs list of periodic comets that have a number designation. ... This article is about the Solar System. ...

Pronunciation

The most standard pronunciation of "Halley" is IPA: /ˈhæli/, to rhyme with "valley". The once-standard alternate pronunciation /ˈheɪli/ (to rhyme with "Bailey") led to rock and roll singer Bill Haley naming his band The Comets. Edmond Halley himself probably pronounced his name /ˈhɔːli/, with the "hall-" rhyming with "call" or "small".^[3] Rock and roll (also spelled Rock n Roll, especially in its first decade), also called rock, is a form of popular music, usually featuring vocals (often with vocal harmony), electric guitars and a strong back beat; other instruments, such as the saxophone, are common in some styles. ... For other uses, see Singer (disambiguation). ... Bill Haley, with his band, the Comets, was one of the first rock and roll acts to tour the United Kingdom. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ...

Edmond Halley's study

Halley's Comet was the first comet to be recognized as periodic. Perceiving that the observed characteristics of the comet of 1682 were nearly the same as those of two comets which had appeared in 1531 (observed by Petrus Apianus) and 1607 (observed by Johannes Kepler in Prague), Halley concluded that all three comets were in fact the same object returning every 76 years (a period that has since been amended to every 75–76 years). After a rough estimate of the perturbations the comet would sustain from the attraction of the planets, he predicted its return for 1758. Halley's prediction of the comet's return proved to be correct, although it was not seen until 25 December 1758 by Johann Georg Palitzsch, a German farmer and amateur astronomer, and did not pass through its perihelion until March 13, 1759; the attraction of Jupiter and Saturn having caused a retardation of 618 days, as was computed by a team of three French mathematicians, Alexis Clairault, Joseph Lalande, and Nicole-Reine Lepaute, previous to its return. Halley did not live to see the comet's return, having died in 1742. Apianus on an 18th century engraving Petrus Apianus (April 16, 1495 – April 21, 1552; also known as Peter Apian) was a German humanist, famous for his works in mathematics, astronomy and cartography. ... Kepler redirects here. ... For other uses, see Prague (disambiguation). ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... Year 1758 (MDCCLVIII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday of the 11-day slower Julian calendar). ... Johann Georg Palitzsch Johann Georg Palitzsch (June 11, 1723 – February 21, 1788) was a German astronomer. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Alexis Claude de Clairault (or Clairaut) (May 3, 1713 – May 17, 1765) was a French mathematician and thinker. ... Joseph Jérôme Lefrançais de Lalande (July 11, 1732 – April 4, 1807) was a French astronomer. ... Nicole-Reine Étable de la Brière Lepaute (1723-1788) was a French astronomer. ...

Notable appearances

Halley's calculations enabled the comet's earlier appearances to be found in the historical record.

Early appearances

A Babylonian tablet recording the appearance of Halley's comet in 164 BC.

The comet's appearance in 1066 was recorded on the Bayeux Tapestry. The caption, ISTI MIRANT STELLA, was translated in a 1966 National Geographic article as "These men wonder at the star."

• 240 BC and earlier: Historical records show that Chinese astronomers observed the comet's appearance in 240 BC and possibly as early as 467 BC. Habitual observations and calculations of appearances after 240 BC are recorded by Chinese, Babylonian, Persian, and other Mesopotamian astronomers.
• 87 BC: According to V.G. Gurzadyan and R. Vardanyan, the "Symbol on Tigranes the Great's crown that features a star with a curved tail may represent the passage of Halley's comet in 87 BC. Tigranes could have seen Halley's comet when it passed closest to the Sun on Aug. 6 in 87 BC according to the researchers, who said the comet would have been a 'most recordable event' — heralding the New Era of the brilliant King of Kings.^[4]
• 12 BC: Some theologians have suggested that the comet's appearance in 12 BC might explain the Biblical story of the Star of Bethlehem.^[5]
• AD 66 : In the Talmud, it is mentioned that "There is a star which appears once in seventy years that makes the captains of the ships err".^[6] Since this quote is attributed to the Rabbi Yehoshua ben Hananiah, if it is indeed a reference to Halley's Comet, it probably refers to the AD 66 perihelion, which was the only one to occur during his lifetime.^[7]
• 837: In this year, it is calculated that Comet Halley may have passed as close as 0.03 AU (3.2 million miles; 5.1 million kilometres) from Earth, by far its closest approach. Its tail may have stretched 90 degrees across the sky.^[8]
• 1066: The comet was seen in England and thought to be an omen: later that year Harold II of England died at the Battle of Hastings. Thus it was a bad omen for Harold, but a good omen for William the Conqueror. Shown on the Bayeux Tapestry, and the accounts which have been preserved represent it as having then appeared to be four times the size of Venus, and to have shone with a light equal to a quarter of that of the Moon. This appearance of the comet is also noted in the Anglo-Saxon Chronicle. Having first seen it as a young boy in 989, Eilmer of Malmesbury declared prophetically in 1066: "You've come, have you?…You've come, you source of tears to many mothers, you evil. I hate you! It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country. I hate you!" ^[9]. Chaco Native Americans in New Mexico recorded this 1066 comet in their petroglyphs.^[10]
• 1301: The artist Giotto di Bondone could have observed the comet and his depiction of the Star of Bethlehem in the Nativity in the Arena Chapel cycle completed in 1305 is a candidate for an early depiction.
• 1456: The comet passed very close to the Earth; its tail extended over 60° of the heavens and took the form of a sabre. According to one story, first appearing in a posthumous biography in 1475 and later embellished and popularized by Pierre-Simon Laplace, Pope Callixtus III excommunicated the 1456 apparition of the comet, believing it to be an ill omen for the Christian defenders of Belgrade, who were at that time being besieged by the armies of the Ottoman Empire. However, no known primary source supports the authenticity of this account.

Image File history File links Size of this preview: 372 × 600 pixelsFull resolution (912 × 1470 pixel, file size: 215 KB, MIME type: image/jpeg) A Babylonian tablet recording Halleys comet during an appearance in 164 BC. [[Image: [[Image: ]]]] File historyClick on a date/time to view the file as... Image File history File links Size of this preview: 372 × 600 pixelsFull resolution (912 × 1470 pixel, file size: 215 KB, MIME type: image/jpeg) A Babylonian tablet recording Halleys comet during an appearance in 164 BC. [[Image: [[Image: ]]]] File historyClick on a date/time to view the file as... Babylonia was an ancient state in Iraq), combining the territories of Sumer and Akkad. ... Image File history File links Tapestry_of_bayeux10. ... Image File history File links Tapestry_of_bayeux10. ... The Bayeux Tapestry (French: Tapisserie de Bayeux) is a 50 cm by 70 m (20 in by 230 ft) long embroidered cloth which depicts the events leading up to the 1066 Norman invasion of England as well as the events of the invasion itself. ... The National Geographic Society was founded in the USA on January 27, 1888, by 33 men interested in organizing a society for the increase and diffusion of geographical knowledge. ... This article is about a king of Armenia in the 1st century BCE. For other historical figures with the same name (including other kings of Armenia) see Tigranes. ... Theology is literally rational discourse concerning God (Greek θεος, theos, God, + λογος, logos, rational discourse). By extension, it also refers to the study of other religious topics. ... Adoration of the Magi by Florentine painter Giotto di Bondone (1267-1337). ... The Talmud (Hebrew: ) is a record of rabbinic discussions pertaining to Jewish law, ethics, customs, and history. ... The astronomical unit (AU or au or a. ... This article is about Earth as a planet. ... This article describes the unit of angle. ... Name Harold Godwinson Lived c. ... Combatants Normans supported by: Bretons (one third of total), Flemings, French Anglo-Saxons, the Þingalið Commanders William of Normandy, Odo of Bayeux Harold Godwinson † Strength 7,000-8,000 7,000-8,000 Casualties Unknown, thought to be around 2,000 killed and wounded Unknown, thought to be around 4... William I ( 1027 – September 9, 1087), was King of England from 1066 to 1087. ... The Bayeux Tapestry (French: Tapisserie de Bayeux) is a 50 cm by 70 m (20 in by 230 ft) long embroidered cloth which depicts the events leading up to the 1066 Norman invasion of England as well as the events of the invasion itself. ... (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... This article is about Earths moon. ... The initial page of the Peterborough Chronicle. ... Stained glass window showing Eilmer, installed in Malmesbury Abbey in 1920 in memory of Rev. ... For the book, see 1066 And All That. ... There are things that have the name Chaco: South America: Gran Chaco, a region in South America Chaco Province, Argentina in the northeastern part of the country Chaco, a region in Paraguay Chaco Department, historical in Paraguay and proposed in Bolivia Gran Chaco Province, Bolivia (in Tarija Department) Chaco War... Giotto di Bondone (c. ... For the Nativity of Jesus, see Nativity of Jesus. ... The Cappella degli Scrovegni in Padua (also known as the Arena Chapel) is regarded as one of the masterpieces of Western Art. ... Pierre-Simon, marquis de Laplace (March 23, 1749 - March 5, 1827) was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy. ... Calistus and Calixtus III redirect here. ... Excommunication is a religious censure used to deprive or suspend membership in a religious community. ... For other uses, see Belgrade (disambiguation). ... Ottoman redirects here. ...

Recent history

The most recent appearances have been in 1835, 1910, and 1986. Halley will next return in 2061.

1835

American satirist and writer Mark Twain was born on November 30, 1835, exactly two weeks after the comet's perihelion. In his biography, he said, "I came in with Halley's comet in 1835. It's coming again next year (1910), and I expect to go out with it. The Almighty has said no doubt, 'Now here are these two unaccountable freaks; they came in together, they must go out together.' " Twain died on April 21, 1910, the day following the comet's subsequent perihelion.^[11][12] The 1985 fantasy film The Adventures of Mark Twain is inspired by this. Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910),[1] better known by the pen name Mark Twain, was an American humanist,[2] humorist, satirist, lecturer and writer. ... is the 334th day of the year (335th in leap years) in the Gregorian calendar. ... | Come and take it, slogan of the Texas Revolution 1835 was a common year starting on Thursday (see link for calendar). ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... is the 111th day of the year (112th in leap years) in the Gregorian calendar. ... Year 1910 (MCMX) was a common year starting on Saturday (link will display calendar) of the Gregorian calendar (or a common year starting on Friday [1] of the 13-day-slower Julian calendar). ... The Adventures of Mark Twain, released in the UK as Comet Quest, is a 1985 stop motion animated film directed by Will Vinton (best known for The California Raisins animation). ...

1910

The April 1910 (which came into view around April 20) approach was notable for several reasons: it was the first approach of which photographs exist, and the comet made a relatively close approach, making it a spectacular sight. Indeed, on May 18, the media (despite the pleas of astronomers) wove sensational tales of mass cyanide poisoning engulfing the planet. In reality, the gas is so diffuse that the world suffered no ill effects from the passage through the tail. is the 138th day of the year (139th in leap years) in the Gregorian calendar. ...

Many people who claim to remember seeing the 1910 apparition are probably in fact remembering a different comet, the Great Daylight Comet of 1910, which surpassed Halley in brilliance and was actually visible in broad daylight for a short time about four months before Halley made its appearance. The Great Daylight Comet of 1910 was a great comet which upstaged the much-anticipated appearance of Halleys Comet in the same year. ...

1986

Comet Halley in 1986

The 1986 approach was the least favourable for Earth observers of all recorded passages of the comet throughout history: the comet did not achieve the spectacular brightness of some previous approaches, and with increased light pollution from urbanization, many people never saw the comet at all. Further, the comet appeared brightest when it was almost invisible from the northern hemisphere in March and April, prompting many amateur astronomers to travel to the southern hemisphere for a glimpse of the interloper. However, the development of space travel allowed scientists the opportunity to study the comet at close quarters, and several probes were launched to do so. The Soviet Vega 1 started returning images of Halley on 1986 March 4, and the first ever of its nucleus, and made its flyby on March 6, followed by Vega 2 making its flyby on March 9. On March 14, the Giotto space probe, launched by the European Space Agency, made a closest pass of the comet's nucleus. There were also two Japanese probes, Suisei and Sakigake. The probes were unofficially known as the Halley Armada. Image File history File links Download high-resolution version (1254x961, 487 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Comet Halley ... Image File history File links Download high-resolution version (1254x961, 487 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Comet Halley ... This time exposure photo of New York City shows sky glow, one form of light pollution. ... CCCP redirects here. ... The Vega mission was a Venus mission which also took advantage of the appearance of Comet Halley in 1986. ... Year 1986 (MCMLXXXVI) was a common year starting on Wednesday (link displays 1986 Gregorian calendar). ... is the 63rd day of the year (64th in leap years) in the Gregorian calendar. ... The solid, central part of a comet is known as the comet nucleus. ... The Vega mission was a Venus mission which also took advantage of the appearance of Comet Halley in 1986. ... In this artists concept, Giotto points its white high-gain antenna dish towards earth with the ring of solar cells facing the sun. ... ESA redirects here. ... Suisei (the Japanese name meaning `Comet) was launched on August 18, 1985 into heliocentric orbit to fly by Comet P/Halley. ... Spacecraft Sakigake Sakigake (MS-T5), was Japans first interplanetary spacecraft and was lauched January 7, 1985 from Kagoshima Space Center. ... The Halley Armada is a group of space probes sent to examine Comet Halley during its 1986 sojourn through the inner solar system. ...

The first person to visually observe comet Halley on its 1986 return was amateur astronomer Stephen James O'Meara on January 24, 1985. O'Meara used a home-built 24" telescope on top of Mauna Kea to detect the magnitude 19.6 comet.^[13] As for the naked eye observing, it was Stephen Edberg (then serving as the Coordinator for Amateur Observations at NASA's Jet Propulsion Laboratory (JPL)) and Charles Morris who were the first to observe Comet Halley with the naked eye in its 1986 apparition. is the 24th day of the year in the Gregorian calendar. ... This article is about the year. ... Mauna Kea is a dormant volcano in the Hawaiian Islands, one of five volcanoes which together form the island of Hawaii. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... For other uses, see NASA (disambiguation). ... The JPL complex in Pasadena, Ca. ...

Based on data, retrieved by Astron, the largest ultraviolet space telescope of the time, during its Halley's Comet observations in December 1985, a group of Soviet scientists developed a model of the comet's coma.^[14] The comet was also observed from space by the International Cometary Explorer. Originally International Sun-Earth Explorer 3 the probe was renamed and freed from its L1 Lagrangian point location in Earth's orbit to intercept comets 21P/Giacobini-Zinner and Halley. Astron Astron was a Soviet astrophysical spacecraft launched on March 23, 1983. ... For other uses, see Ultraviolet (disambiguation). ... CCCP redirects here. ... The comet Ikeya-Zhang exhibiting a bright, condensed coma (march 2002) In astronomy, the nebulous envelope around the nucleus of a comet is called its coma (from the Latin word for hair). It is formed when the comet passes close to the sun on its highly elliptical orbit; as the... The International Cometary Explorer (ICE) spacecraft was originally known as International Sun/Earth Explorer 3 (ISEE-3) satellite, launched August 12, 1978. ... A contour plot of the effective potential (the Hills Surfaces) of a two-body system (the Sun and Earth here), showing the five Lagrange points. ... Comet Giacobini-Zinner was discovered by Michel Giacobini (Nice, France) in Aquarius on December 20, 1900. ...

Two Space Shuttle missions — the ill-fated STS-51-L (the Challenger disaster) and STS-61-E — were scheduled to observe Comet Halley from low Earth orbit. 61-E would have been flown by Challenger in March 1986, carrying the ASTRO-1 platform to study the comet. The mission was canceled, and ASTRO-1 would not fly until late 1990 on STS-35.^[15] This article is about the space vehicle. ... The launch of the Space Shuttle Challenger on mission 51L/STS-33, the 25th of the STS (Space Transportation System) program, began at an estimated time of 16:38:00. ... For further information about Challengers mission and crew, see STS-51-L. The iconic image of Space Shuttle Challengers smoke plume after its breakup 73 seconds after launch. ... A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ... Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASAs second Space Shuttle orbiter to be put into service, Columbia being the first. ... // (total flights to date in parentheses) Vance D. Brand (4), Commander Guy S. Gardner (2), Pilot Jeffrey A. Hoffman (2), Mission Specialist 1 John M. Lounge (3), Mission Specialist 2 Robert A. Parker (2), Mission Specialist 3 Samuel T. Durrance (1), Payload Specialist 1 Ronald A. Parise (1), Payload Specialist...

Origin

Comets are believed to have two separate points of origin in the Solar System: the Kuiper belt, a flat disc of icy debris between 38 AU (Pluto's orbit) and 50 AU from the Sun, and the Oort cloud, a sphere of cometary bodies which has its inner edge at 50,000 AU. Short period comets (those with orbits lasting 200 years or less) are generally accepted to have emerged from the Kuiper belt, while long period comets, such as Hale-Bopp, whose orbits last for thousands of years, are believed to originate in the Oort cloud. Halley is unusual in that while it is a short period comet, its ultimate origin lies in the Oort cloud, not the Kuiper belt. Its orbit is such that it is believed to have been originally a long period comet but to have been captured by the gravity of the giant planets and sent into the inner Solar System. Halley is grouped with other comets that share this orbit into the Halley family comets.^[16] The Kuiper belt, derived from data from the Minor Planet Center. ... Artists rendering of the Oort cloud and the Kuiper Belt. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... A close-up of Hale-Bopp Comet Hale-Bopp (formally designated C/1995 O1) was probably the most widely observed comet of the 20th century, and one of the brightest seen for many decades. ...

Orbit

The orbits of three periodic comets, Halley, Borrelly and Ikeya-Zhang, set against the orbits of the outer planets and Pluto. Halley's is to the left

Halley's orbit is highly elliptical, and focused on the Sun. Its perihelion, its closest distance to the Sun, is just 0.6 AU (between the orbits of Mercury and Venus), while its aphelion, or farthest distance from the Sun, is 35 AU, or roughly the distance of Pluto. Unusually for an object in the Solar System, Halley's orbit is retrograde; it orbits the Sun in the opposite direction to the planets, or clockwise from above the Sun's north pole. Its orbit is highly inclined (18°) to the ecliptic, with much of it lying below the orbits of the planets (assuming Earth's north pole is "up").^[17][18] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The following is the IAUs list of periodic comets. ... Comet Borrelly (formally designated 19P/Borrelly) is a periodic comet, which was visited by the space craft Deep Space 1. ... Comet Ikeya-Zhang (Chinese, Japanese: æ± è°·-張彗星, officially designated 153P/Ikeya-Zhang) is a comet discovered independently by two astronomers from Japan and China in 2002. ... The outer planets are those planets that have been discovered in the modern era. ... For other uses, see Pluto (disambiguation). ... Elliptical may refer to: Ellipse: a shape and mathematical construct Elliptical trainer: an exercise machine This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about the planet. ... For other uses, see Venus (disambiguation). ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... For other uses, see Pluto (disambiguation). ... Direct motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called prograde motion. ... Sol redirects here. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...

Due to Halley's highly eccentric orbit, it has one of the highest velocities relative to the Earth in the solar system. The 1910 passage was at a relative velocity of 70.56 km/s (157,800 MPH).^[19] Relative velocity is a measurement of velocity between two objects moving in different frames of reference. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ...

Structure and composition

The Giotto mission gave planetary scientists their first view of Halley's surface and structure. Although its coma may extend about 100 million kilometers into space,^[20] Halley's nucleus is relatively small (barely 15 kilometers long, 8 kilometres wide and 8 kilometers thick) and roughly peanut-shaped. Its mass is extremely low; roughly 2.2×10¹⁴ kg.^[21] Its average density is about 0.6 g/cm³, indicating that it is very loosely constructed.^[22] Its albedo is about 4 percent, meaning that only 4 percent of the sunlight hitting it is reflected; about what one would expect for coal. Thus, despite appearing brilliant white to observers on Earth, Halley's comet is in fact pitch black. Its nucleus has an albedo only of 0.03, darker then coal. As it approaches the inner Solar System, the Sun warms it, causing its surface to sublimate (change directly from a solid to a gas), and jets of volatile material to burst from its black surface. The nucleus rotates every 52 hours, and its day side is far more active than its night side. The gases ejected from the nucleus are 80 percent water vapour, 17 percent carbon monoxide and 3–4 percent carbon dioxide^[23] with traces of hydrocarbons.^[24] The comet Ikeya-Zhang exhibiting a bright, condensed coma (march 2002) In astronomy, the nebulous envelope around the nucleus of a comet is called its coma (from the Latin word for hair). It is formed when the comet passes close to the sun on its highly elliptical orbit; as the... The solid, central part of a comet is known as the comet nucleus. ... Binomial name L. This article is about the legume. ... For other uses, see Albedo (disambiguation). ... For other uses, see Albedo (disambiguation). ... This article does not cite any references or sources. ... R-phrases , , , , S-phrases , , , , Flash point Flammable gas Related Compounds Related oxides carbon dioxide; carbon suboxide; dicarbon monoxide; carbon trioxide Supplementary data page Structure and properties n, εr, etc. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

The nucleus is covered with a layer of dust, which retains heat. Each large dust grain is thought to consist of many tiny particles with spaces in between. Some of these spaces are filled with ice, and others are empty. When Halley's comet is closest to the Sun, temperatures can rise to about 77 °C. Near the Sun, several tons of gas and dust are emitted each second in the jets. Halley has several shallow craters which are about 1 km in diameter.

Meteor showers

Orionid meteor striking the sky below the Milky Way and to the right of Venus. Zodiacal light is also seen at the image.

Because its orbit comes close to Earth's orbit in two places, Comet Halley is the parent body of two meteor showers: the Eta Aquarids in early May, and the Orionids in late October.^[25] The Eta Aquarids show orbital similarites approaching Earth as they do of Mars and so a meteor shower at Mars is anticipated there as well^[26] but this time appearing to come from Lambda Gemini. Image File history File links Size of this preview: 800 × 533 pixelsFull resolution‎ (1,944 × 1,296 pixels, file size: 2. ... Image File history File links Size of this preview: 800 × 533 pixelsFull resolution‎ (1,944 × 1,296 pixels, file size: 2. ... The Orionids are a meteor shower that occurs throughout October into early November. ... “Meteor” redirects here. ... For other uses, see Milky Way (disambiguation). ... For other uses, see Venus (disambiguation). ... The zodiacal light in the eastern sky before the beginning of morning twilight. ... Photo of a burst of meteors with extended exposure time A meteor is the visible path of a meteoroid that enters the Earths (or another bodys) atmosphere, commonly called a shooting star or falling star. ... Categories: Planetology | Astronomy stubs ... The Eta Aquarids are a meteor shower associated with Comet Halley. ... The Orionids are a meteor shower that occurs throughout October into early November. ...

Designation

This table sets out the astronomical designation for various apparitions of Halley's Comet. For example, "(1P/1982 U1, 1986 III, 1982i" indicates that for the perihelion in 1986, Halley's Comet was the first period comet known (designated 1P) and this apparition was the first seen in "half-month" U (the first half of November) in 1982 (giving 1P/1982 U1); it was the third comet past perihelion in 1986 (1986 III); and it was the ninth comet spotted in 1982 (provisional designation 1982i). The perihelion dates of each apparition are shown.^[27] The perihelion dates farther from the present are approximate, mainly because of uncertainties in the modeling of non-gravitational effects. Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... Generally, an apparition is act or instance of appearing. ... Year 1986 (MCMLXXXVI) was a common year starting on Wednesday (link displays 1986 Gregorian calendar). ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ...

Note that perihelion dates 1607 and later are in the Gregorian calendar, while perihelion dates of 1531 and earlier are in the Julian calendar.^[28] is the 145th day of the year (146th in leap years) in the Gregorian calendar. ... Centuries: 4th century BC - 3rd century BC - 2nd century BC Decades: 290s BC 280s BC 270s BC 260s BC 250s BC - 240s BC - 230s BC 220s BC 210s BC 200s BC 190s BC Years: 245 BC 244 BC 243 BC 242 BC 241 BC - 240 BC - 239 BC 238 BC... is the 316th day of the year (317th in leap years) in the Gregorian calendar. ... Centuries: 3rd century BC - 2nd century BC - 1st century BC Decades: 210s BC 200s BC 190s BC 180s BC 170s BC - 160s BC - 150s BC140s BC 130s BC 120s BC 110s BC Years: 169 BC 168 BC 167 BC 166 BC 165 BC - 164 BC - 163 BC 162 BC 161... is the 218th day of the year (219th in leap years) in the Gregorian calendar. ... Lucius Cornelius Cinna is elected consul of Rome, thus returning the rule of Rome back to the democrats. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... Centuries: 2nd century BC - 1st century BC - 1st century Decades: 60s BC 50s BC 40s BC 30s BC 20s BC - 10s BC - 0s 10s 20s 30s 40s Years: 17 BC 16 BC 15 BC 14 BC 13 BC 12 BC 11 BC 10 BC 9 BC 8 BC 7 BC... is the 25th day of the year in the Gregorian calendar. ... This article is about the year 66. ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Events Construction of the Temple of Antoninus and Faustina in Rome. ... is the 137th day of the year (138th in leap years) in the Gregorian calendar. ... May 16 - Elagabalus is declared Roman Emperor. ... is the 110th day of the year (111th in leap years) in the Gregorian calendar. ... Events Roman Empire Diocletian beseiges Achilleus in Egypt, capturing him. ... is the 47th day of the year in the Gregorian calendar. ... Events 4 May: Spearthrower Owl becomes emperor of Teotihuacan. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Events April 7 - The Huns sack Metz June 20 - Attila, king of the Huns is defeated at Troyes by Aëtius in the Battle of Chalons. ... is the 270th day of the year (271st in leap years) in the Gregorian calendar. ... Battle of Daras: Belisarius and Hermogenes defeat the Persians in a major battle which blunts a Persian offensive into Roman Mesopotamia. ... is the 74th day of the year (75th in leap years) in the Gregorian calendar. ... To suck the phallus or penis of another. ... is the 275th day of the year (276th in leap years) in the Gregorian calendar. ... Events Wu Ze Tian took power in China. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... Events Maya civilization city of Dos Pilas is abandoned. ... is the 59th day of the year in the Gregorian calendar. ... Events Pietro Tradonico elected Doge of Venice. ... is the 199th day of the year (200th in leap years) in the Gregorian calendar. ... Events Orso II Participazio becomes Doge of Venice Patriarch Nicholas I Mysticus becomes patriarch of Constantinople Births November 23 - Otto I the Great Holy Roman Emperor (+ 973) Abd-ar-rahman III - prince of the Umayyad dynasty Deaths Oleg of Kiev Categories: 912 ... is the 248th day of the year (249th in leap years) in the Gregorian calendar. ... For the video game developers, see 989 Studios. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... For the book, see 1066 And All That. ... is the 108th day of the year (109th in leap years) in the Gregorian calendar. ... Events Pope Lucius II is succeeded by Pope Eugene III Nur ad-Din ascends to power in Syria Construction begins on Notre-Dame dChartres in Chartres, France Korean historian Kim Pusik compiled the historical text Samguk Sagi. ... is the 271st day of the year (272nd in leap years) in the Gregorian calendar. ... Centuries: 12th century - 13th century - 14th century Decades: 1170s 1180s 1190s 1200s 1210s - 1220s - 1230s 1240s 1250s 1260s 1270s Years: 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 See also: 1222 state leaders Events Foundation of the University of Padua Completion of the Cistercian convent in Alcobaca... is the 298th day of the year (299th in leap years) in the Gregorian calendar. ... Events February 7 - Edward of Caernarvon (later King Edward II of England) becomes the first Prince of Wales End of the reign of Emperor Go-Fushimi, emperor of Japan Emperor Go-Nijō ascends to the throne of Japan Dante was sent into Exile in Florence. ... is the 314th day of the year (315th in leap years) in the Gregorian calendar. ... Events March - John Wyclif tried to gain public favour by laying his theses before parliament, and then made them public in a tract. ... is the 160th day of the year (161st in leap years) in the Gregorian calendar. ... // Events July 7 - Joan of Arc acquitted (but she had already been executed). ... is the 238th day of the year (239th in leap years) in the Gregorian calendar. ... January 26 - Lisbon, Portugal is hit by an earthquake - thousands die. ... is the 300th day of the year (301st in leap years) in the Gregorian calendar. ... Year 1607 (MDCVII) was a common year starting on Monday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday of the 10-day slower Julian calendar). ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... Year 1682 (MDCLXXXII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday of the 10-day slower Julian calendar). ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... Year 1758 (MDCCLVIII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday of the 11-day slower Julian calendar). ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... | Come and take it, slogan of the Texas Revolution 1835 was a common year starting on Thursday (see link for calendar). ... is the 110th day of the year (111th in leap years) in the Gregorian calendar. ... Year 1910 (MCMX) was a common year starting on Saturday (link will display calendar) of the Gregorian calendar (or a common year starting on Friday [1] of the 13-day-slower Julian calendar). ... is the 40th day of the year in the Gregorian calendar. ... Year 1986 (MCMLXXXVI) was a common year starting on Wednesday (link displays 1986 Gregorian calendar). ... is the 209th day of the year (210th in leap years) in the Gregorian calendar. ... For the book, see 2061: Odyssey Three. ... For the calendar of religious holidays and periods, see liturgical year. ... The Julian calendar was a reform of the Roman calendar which was introduced by Julius Caesar in 46 BC and came into force in 45 BC (709 ab urbe condita). ...

External links

• cometography.com
• seds.org
• Orbital simulation from JPL (Java) / Ephemeris
• Donald Yeomans, "Great Comets in History"
• Vega 2 Images of Comet Halley

References

Footnotes