Comet Shoemaker–Levy 9

Comet Shoemaker–Levy 9 (formally designated D/1993 F2) was a comet that broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects.^[2] This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its possible role in reducing space debris in the inner Solar System.

The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy.^[3] Shoemaker–Levy 9 had been captured by Jupiter and was orbiting the planet at the time. It was located on the night of March 24, 1993 in a photograph taken with the 40 cm (16 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by Jupiter around 20–30 years earlier.

Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull apart the comet. The comet was later observed as a series of fragments ranging up to 2 km (1.2 mi) in diameter. These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994 at a speed of approximately 60 km/s (37 mi/s) (Jupiter's escape velocity) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.

Discovery

While conducting a program of observations designed to uncover near-Earth objects, the Shoemakers and Levy discovered Comet Shoemaker–Levy 9 on the night of March 24, 1993 in a photograph taken with the 0.4 m (1.3 ft) Schmidt telescope at the Palomar Observatory in California. The comet was thus a serendipitous discovery, but one that quickly overshadowed the results from their main observing program.^[4]

Comet Shoemaker–Levy 9 was the ninth periodic comet (a comet whose orbital period is 200 years or less) discovered by the Shoemakers and Levy, hence its name. It was their eleventh comet discovery overall including their discovery of two non-periodic comets, which use a different nomenclature. The discovery was announced in IAU Circular 5725 on March 27, 1993.^[3]

The discovery image gave the first hint that comet Shoemaker–Levy 9 was an unusual comet, as it appeared to show multiple nuclei in an elongated region about 50 arcseconds long and 10 arcseconds wide. Brian G. Marsden of the Central Bureau for Astronomical Telegrams noted that the comet lay only about 4 degrees from Jupiter as seen from Earth, and that although this could of course be a line of sight effect, its apparent motion in the sky suggested that it was physically close to it.^[3] Because of this, he suggested that the Shoemakers and David Levy had discovered the fragments of a comet that had been disrupted by Jupiter's gravity.

Jupiter-orbiting comet

Orbital studies of the new comet soon revealed that it was orbiting Jupiter rather than the Sun, unlike all other comets known at the time. Its orbit around Jupiter was very loosely bound, with a period of about 2 years and an apoapsis (the point in the orbit farthest from the planet) of 0.33 astronomical units (49 million kilometres; 31 million miles). Its orbit around the planet was highly eccentric (e = 0.9986).^[5]

Tracing back the comet's orbital motion revealed that it had been orbiting Jupiter for some time. It is likely that it was captured from a solar orbit in the early 1970s, although the capture may have occurred as early as the mid-1960s.^[6] Several other observers found images of the comet in precovery images obtained before March 24, including Kin Endate from a photograph exposed on March 15, S. Otomo on March 17, and a team led by Eleanor Helin from images on March 19.^[7] No precovery images dating back to earlier than March 1993 have been found. Before the comet was captured by Jupiter, it was probably a short-period comet with an aphelion just inside Jupiter's orbit, and a perihelion interior to the asteroid belt.^[8]

The volume of space within which an object can be said to orbit Jupiter is defined by Jupiter's Hill sphere (also called the Roche sphere). When the comet passed Jupiter in the late 1960s or early 1970s, it happened to be near its aphelion, and found itself slightly within Jupiter's Hill sphere. Jupiter's gravity nudged the comet towards it. Because the comet's motion with respect to Jupiter was very small, it fell almost straight toward Jupiter, which is why it ended up on a Jupiter-centric orbit of very high eccentricity – that is to say, the ellipse was nearly flattened out.^[9]

The comet had apparently passed extremely close to Jupiter on July 7, 1992, just over 40,000 km (25,000 mi) above its cloud tops—a smaller distance than Jupiter's radius of 70,000 km (43,000 mi), and well within the orbit of Jupiter's innermost moon Metis and the planet's Roche limit, inside which tidal forces are strong enough to disrupt a body held together only by gravity.^[9] Although the comet had approached Jupiter closely before, the July 7 encounter seemed to be by far the closest, and the fragmentation of the comet is thought to have occurred at this time. Each fragment of the comet was denoted by a letter of the alphabet, from "fragment A" through to "fragment W", a practice already established from previously observed broken-up comets.^[10]

More exciting for planetary astronomers was that the best orbital calculations suggested that the comet would pass within 45,000 km (28,000 mi) of the center of Jupiter, a distance smaller than the planet's radius, meaning that there was an extremely high probability that SL9 would collide with Jupiter in July 1994.^[11] Studies suggested that the train of nuclei would plow into Jupiter's atmosphere over a period of about five days.^[9]

Predictions for the collision

The discovery that the comet was likely to collide with Jupiter caused great excitement within the astronomical community and beyond, as astronomers had never before seen two significant Solar System bodies collide. Intense studies of the comet were undertaken, and as its orbit became more accurately established, the possibility of a collision became a certainty. The collision would provide a unique opportunity for scientists to look inside Jupiter's atmosphere, as the collisions were expected to cause eruptions of material from the layers normally hidden beneath the clouds.^[5]

Astronomers estimated that the visible fragments of SL9 ranged in size from a few hundred metres (around 1,000 ft) to two kilometres (1.2 mi) across, suggesting that the original comet may have had a nucleus up to 5 km (3.1 mi) across—somewhat larger than Comet Hyakutake, which became very bright when it passed close to the Earth in 1996. One of the great debates in advance of the impact was whether the effects of the impact of such small bodies would be noticeable from Earth, apart from a flash as they disintegrated like giant meteors.^[12] The most optimistic prediction was that large, asymmetric ballistic fireballs would rise above the limb of Jupiter and into sunlight to be visible from Earth.^[13] Other suggested effects of the impacts were seismic waves travelling across the planet, an increase in stratospheric haze on the planet due to dust from the impacts, and an increase in the mass of the Jovian ring system. However, given that observing such a collision was completely unprecedented, astronomers were cautious with their predictions of what the event might reveal.^[5]

Impacts

Jupiter in ultraviolet (about 2.5 hours after R's impact). The black dot near the top is Io transiting Jupiter.^[14]

Jupiter in infrared, Shoemaker–Levy 9 collision (left), Io (right)

Anticipation grew as the predicted date for the collisions approached, and astronomers trained terrestrial telescopes on Jupiter. Several space observatories did the same, including the Hubble Space Telescope, the ROSAT X-ray-observing satellite, and significantly the Galileo spacecraft, then on its way to a rendezvous with Jupiter scheduled for 1995. Although the impacts took place on the side of Jupiter hidden from Earth, Galileo, then at a distance of 1.6 AU (240 million km; 150 million mi) from the planet, was able to see the impacts as they occurred. Jupiter's rapid rotation brought the impact sites into view for terrestrial observers a few minutes after the collisions.^[15]

Two other satellites made observations at the time of the impact: the Ulysses spacecraft, primarily designed for solar observations, was pointed towards Jupiter from its location 2.6 AU (390 million km; 240 million mi) away, and the distant Voyager 2 probe, some 44 AU (6.6 billion kilometres; 4.1 billion miles) from Jupiter and on its way out of the Solar System following its encounter with Neptune in 1989, was programmed to look for radio emission in the 1–390 kHz range.^[16]

Hubble Space Telescope images of a fireball from the first impact appearing over the limb of the planet

The first impact occurred at 20:13 UTC on July 16, 1994, when fragment A of the nucleus entered Jupiter's southern hemisphere at a speed of about 60 km/s (35 mi/s).^[2] Instruments on Galileo detected a fireball that reached a peak temperature of about 24,000 K (23,700 °C; 42,700 °F), compared to the typical Jovian cloudtop temperature of about 130 K (−143 °C; −226 °F), before expanding and cooling rapidly to about 1,500 K (1,230 °C; 2,240 °F) after 40 seconds. The plume from the fireball quickly reached a height of over 3,000 km (1,900 mi).^[17] A few minutes after the impact fireball was detected, Galileo measured renewed heating, probably due to ejected material falling back onto the planet. Earth-based observers detected the fireball rising over the limb of the planet shortly after the initial impact.^[18]

Despite published predictions,^[13] astronomers had not expected to see the fireballs from the impacts^[19] and did not have any idea in advance how visible the other atmospheric effects of the impacts would be from Earth. Observers soon saw a huge dark spot after the first impact. The spot was visible even in very small telescopes, and was about 6,000 km (3,700 mi) (one Earth radius) across. This and subsequent dark spots were thought to have been caused by debris from the impacts, and were markedly asymmetric, forming crescent shapes in front of the direction of impact.^[20]

Over the next six days, 21 distinct impacts were observed, with the largest coming on July 18 at 07:33 UTC when fragment G struck Jupiter. This impact created a giant dark spot over 12,000 km (7,500 mi) across, and was estimated to have released an energy equivalent to 6,000,000 megatons of TNT (600 times the world's nuclear arsenal).^[21] Two impacts 12 hours apart on July 19 created impact marks of similar size to that caused by fragment G, and impacts continued until July 22, when fragment W struck the planet.^[22]

Observations and discoveries

Chemical studies

Brown spots mark impact sites on Jupiter's southern hemisphere.

Observers hoped that the impacts would give them a first glimpse of Jupiter beneath the cloud tops, as lower material was exposed by the comet fragments punching through the upper atmosphere. Spectroscopic studies revealed absorption lines in the Jovian spectrum due to diatomic sulfur (S₂) and carbon disulfide (CS₂), the first detection of either in Jupiter, and only the second detection of S₂ in any astronomical object. Other molecules detected included ammonia (NH₃) and hydrogen sulfide (H₂S). The amount of sulfur implied by the quantities of these compounds was much greater than the amount that would be expected in a small cometary nucleus, showing that material from within Jupiter was being revealed. Oxygen-bearing molecules such as sulfur dioxide were not detected, to the surprise of astronomers.^[23]

As well as these molecules, emission from heavy atoms such as iron, magnesium and silicon was detected, with abundances consistent with what would be found in a cometary nucleus. Although a substantial amount of water was detected spectroscopically, it was not as much as predicted beforehand, meaning that either the water layer thought to exist below the clouds was thinner than predicted, or that the cometary fragments did not penetrate deeply enough.^[24]

Waves

As predicted beforehand, the collisions generated enormous waves that swept across Jupiter at speeds of 450 m/s (1,476 ft/s) and were observed for over two hours after the largest impacts. The waves were thought to be travelling within a stable layer acting as a waveguide, and some scientists thought the stable layer must lie within the hypothesised tropospheric water cloud. However, other evidence seemed to indicate that the cometary fragments had not reached the water layer, and the waves were instead propagating within the stratosphere.^[25]

Other observations

A sequence of Galileo images, taken several seconds apart, showing the appearance of the fireball of fragment W on the dark side of Jupiter

Radio observations revealed a sharp increase in continuum emission at a wavelength of 21 cm (8.3 in) after the largest impacts, which peaked at 120% of the normal emission from the planet. This was thought to be due to synchrotron radiation, caused by the injection of relativistic electrons—electrons with velocities near the speed of light—into the Jovian magnetosphere by the impacts.^[26]

About an hour after fragment K entered Jupiter, observers recorded auroral emission near the impact region, as well as at the antipode of the impact site with respect to Jupiter's strong magnetic field. The cause of these emissions was difficult to establish due to a lack of knowledge of Jupiter's internal magnetic field and of the geometry of the impact sites. One possible explanation was that upwardly accelerating shock waves from the impact accelerated charged particles enough to cause auroral emission, a phenomenon more typically associated with fast-moving solar wind particles striking a planetary atmosphere near a magnetic pole.^[27]

Some astronomers had suggested that the impacts might have a noticeable effect on the Io torus, a torus of high-energy particles connecting Jupiter with the highly volcanic moon Io. High resolution spectroscopic studies found that variations in the ion density, rotational velocity, and temperatures at the time of impact and afterwards were within the normal limits.^[28]

Post-impact analysis

A reddish, asymmetric ejecta pattern

Several models were devised to compute the density and size of Shoemaker–Levy 9. Its average density was calculated to be about 0.5 g/cm³ (0.018 lb/cu in); the breakup of a much less dense comet would not have resembled the observed string of objects. The size of the parent comet was calculated to be about 1.8 km (1.1 mi) in diameter.^[29][30] These predictions were among the few that were actually confirmed by subsequent observation.^[31]

One of the surprises of the impacts was the small amount of water revealed compared to prior predictions.^[32] Before the impact, models of Jupiter's atmosphere had indicated that the break-up of the largest fragments would occur at atmospheric pressures of anywhere from 30 kilopascals to a few tens of megapascals (from 0.3 to a few hundred bar),^[24] with some predictions that the comet would penetrate a layer of water and create a bluish shroud over that region of Jupiter.^[12]

Astronomers did not observe large amounts of water following the collisions, and later impact studies found that fragmentation and destruction of the cometary fragments in an 'airburst' probably occurred at much higher altitudes than previously expected, with even the largest fragments being destroyed when the pressure reached 250 kPa (36 psi), well above the expected depth of the water layer. The smaller fragments were probably destroyed before they even reached the cloud layer.^[24]

Longer-term effects

The visible scars from the impacts could be seen on Jupiter for many months. They were extremely prominent, and observers described them as even more easily visible than the Great Red Spot. A search of historical observations revealed that the spots were probably the most prominent transient features ever seen on the planet, and that although the Great Red Spot is notable for its striking color, no spots of the size and darkness of those caused by the SL9 impacts have ever been recorded before.^[33]

Spectroscopic observers found that ammonia and carbon disulfide persisted in the atmosphere for at least fourteen months after the collisions, with a considerable amount of ammonia being present in the stratosphere as opposed to its normal location in the troposphere.^[34]

Counterintuitively, the atmospheric temperature dropped to normal levels much more quickly at the larger impact sites than at the smaller sites: at the larger impact sites, temperatures were elevated over a region 15,000 to 20,000 km (9,300 to 12,400 mi) wide, but dropped back to normal levels within a week of the impact. At smaller sites, temperatures 10 K (18 °F) higher than the surroundings persisted for almost two weeks.^[35] Global stratospheric temperatures rose immediately after the impacts, then fell to below pre-impact temperatures 2–3 weeks afterwards, before rising slowly to normal temperatures.^[36]

Frequency of impacts

A chain of craters on Ganymede, probably caused by a similar impact event. The picture covers an area approximately 190 km (120 mi) across.

SL9 is not unique in having orbited Jupiter for a time; five comets, (including 82P/Gehrels, 147P/Kushida–Muramatsu, and 111P/Helin–Roman–Crockett) are known to have been temporarily captured by the planet.^[37][38] Cometary orbits around Jupiter are unstable, as they will be highly elliptical and likely to be strongly perturbed by the Sun's gravity at apojove (the furthest point on the orbit from the planet).

By far the most massive planet in the Solar System, Jupiter can capture objects relatively frequently, but the size of SL9 makes it a rarity: one post-impact study estimated that comets 0.3 km (0.19 mi) in diameter impact the planet once in approximately 500 years and those 1.6 km (0.99 mi) in diameter do so just once in every 6,000 years.^[39]

There is very strong evidence that comets have previously been fragmented and collided with Jupiter and its satellites. During the Voyager missions to the planet, planetary scientists identified 13 crater chains on Callisto and three on Ganymede, the origin of which was initially a mystery.^[40] Crater chains seen on the Moon often radiate from large craters, and are thought to be caused by secondary impacts of the original ejecta, but the chains on the Jovian moons did not lead back to a larger crater. The impact of SL9 strongly implied that the chains were due to trains of disrupted cometary fragments crashing into the satellites.^[41]

Impact of July 19, 2009

On July 19, 2009, exactly 15 years after the SL9 impacts, a new black spot about the size of the Pacific Ocean appeared in Jupiter's southern hemisphere. Thermal infrared measurements showed the impact site was warm and spectroscopic analysis detected the production of excess hot ammonia and silica-rich dust in the upper regions of Jupiter's atmosphere. Scientists have concluded that another impact event had occurred, but this time a more compact and strong object, probably a small undiscovered asteroid, was the cause.^[42]

Jupiter as a "cosmic vacuum cleaner"

The impact of SL9 highlighted Jupiter's role as a "cosmic vacuum cleaner" (or in deference to the ancients' planetary correspondences to the major organs in the human body, a "cosmic liver") for the inner Solar System. The planet's strong gravitational influence leads to many small comets and asteroids colliding with the planet, and the rate of cometary impacts on Jupiter is thought to be between 2000-8000 times higher than the rate on Earth.^[43]

The extinction of the dinosaurs at the end of the Cretaceous period is generally thought to have been caused by the Cretaceous–Paleogene impact event, which created the Chicxulub crater,^[44] demonstrating that impacts are a serious threat to life on Earth. Astronomers have speculated that without Jupiter to mop up potential impactors, extinction events might have been more frequent on Earth, and complex life might not have been able to develop.^[45] This is part of the argument used in the Rare Earth hypothesis.

In 2009, it was shown that the presence of a smaller planet at Jupiter's position in the Solar System might increase the impact rate of comets on the Earth significantly. A planet of Jupiter's mass still seems to provide increased protection against asteroids, but the total effect on all orbital bodies within the Solar System is unclear.^[46][47] Computer simulations in 2016 have continued to erode the theory.^[48]

See also

• Atmosphere of Jupiter
• 73P/Schwassmann–Wachmann, a near-Earth comet in the process of disintegrating

References

Notes

Bibliography

• Chodas P. W., and Yeomans D. K. (1996), The Orbital Motion and Impact Circumstances of Comet Shoemaker–Levy 9, in The Collision of Comet Shoemaker–Levy 9 and Jupiter, edited by K. S. Noll, P. D. Feldman, and H. A. Weaver, Cambridge University Press, pp. 1–30
• Chodas P. W. (2002), Communication of Orbital Elements to Selden E. Ball, Jr. Accessed February 21, 2006

External links

Wikimedia Commons has media related to Comet Shoemaker-Levy 9.

Listen to this article (info/dl)

This audio file was created from a revision of the "Comet Shoemaker–Levy 9" article dated 2006-04-14, and does not reflect subsequent edits to the article. (Audio help)

More spoken articles

• Comet Shoemaker–Levy 9 FAQ
• Comet Shoemaker–Levy 9 Photo Gallery
• Downloadable gif Animation showing time course of impact and size relative to earthsize
• http://www.cv.nrao.edu/~pmurphy/patsl9.html
• Jupiter Swallows Comet Shoemaker Levy 9 APOD: 2000 November 5
• Comet Shoemaker–Levy Collision with Jupiter
• National Space Science Data Center information
• Simulation of the orbit of SL-9 showing the passage that fragmented the comet and the collision 2 years later
• Interactive space simulator that includes accurate 3D simulation of the Shoemaker Levy 9 collision

Comets
Features Nucleus Coma Tails Antitail Comet dust Meteor shower Types Periodic Numbered Lost Halley-type Jupiter-family Encke-type Main-belt Non-periodic Hyperbolic Unknown-orbit Great Comet Sungrazing (Kreutz) Extinct Exocomet Interstellar Related Naming of comets Centaur Comet discoverers LINEAR Extraterrestrial atmosphere Oort cloud Small Solar System body Asteroid Space missions Comet Hopper CONTOUR CRAF Deep Impact/EPOXI Deep Space 1 Giotto Hayabusa Mk2 ICE Marco Polo Rosetta Philae Timeline Sakigake Stardust/NeXT Suisei Ulysses Vega program Vega 1 Vega 2 Vesta Latest C/2016 U1 (NEOWISE) C/2015 G2 (MASTER) C/2015 F5 (SWAN-XingMing) C/2015 F3 C/2014 Q2 (Lovejoy) C/2014 E2 (Jacques) C/2013 US10 (Catalina) C/2013 A1 (Siding Spring) C/2012 S4 (PANSTARRS) C/2012 K1 (PANSTARRS) Culture and speculation Antimatter comet Comets in fiction Fictional comets Comet vintages
Lists of comets (more) Periodic comets Until 1985 (all) 1P/Halley 2P/Encke 3D/Biela 4P/Faye 5D/Brorsen 6P/d'Arrest 7P/Pons–Winnecke 8P/Tuttle 9P/Tempel 10P/Tempel 11P/Tempel–Swift–LINEAR 12P/Pons–Brooks 13P/Olbers 14P/Wolf 15P/Finlay 16P/Brooks 17P/Holmes 18D/Perrine–Mrkos 19P/Borrelly 20D/Westphal 21P/Giacobini–Zinner 22P/Kopff 23P/Brorsen–Metcalf 24P/Schaumasse 25D/Neujmin 26P/Grigg–Skjellerup 27P/Crommelin 28P/Neujmin 29P/Schwassmann–Wachmann 30P/Reinmuth 31P/Schwassmann–Wachmann 32P/Comas Solà 33P/Daniel 34D/Gale 35P/Herschel–Rigollet 36P/Whipple 37P/Forbes 38P/Stephan–Oterma 39P/Oterma 40P/Väisälä 41P/Tuttle–Giacobini–Kresák 42P/Neujmin 43P/Wolf–Harrington 44P/Reinmuth 45P/Honda–Mrkos–Pajdušáková 46P/Wirtanen 47P/Ashbrook–Jackson 48P/Johnson 49P/Arend–Rigaux 50P/Arend 51P/Harrington 52P/Harrington–Abell 53P/Van Biesbroeck 54P/de Vico–Swift–NEAT 55P/Tempel–Tuttle 56P/Slaughter–Burnham 57P/du Toit–Neujmin–Delporte 58P/Jackson–Neujmin 59P/Kearns–Kwee 60P/Tsuchinshan 61P/Shajn–Schaldach 62P/Tsuchinshan 63P/Wild 64P/Swift–Gehrels 65P/Gunn 66P/du Toit 67P/Churyumov–Gerasimenko 68P/Klemola 69P/Taylor 70P/Kojima 71P/Clark 72P/Denning–Fujikawa 73P/Schwassmann–Wachmann 74P/Smirnova–Chernykh 75D/Kohoutek 76P/West–Kohoutek–Ikemura 77P/Longmore 78P/Gehrels 79P/du Toit–Hartley 80P/Peters–Hartley 81P/Wild 82P/Gehrels 83D/Russell 84P/Giclas 85P/Boethin 86P/Wild 87P/Bus 88P/Howell 89P/Russell 90P/Gehrels 91P/Russell 92P/Sanguin 93P/Lovas 94P/Russell 95P/Chiron 96P/Machholz 97P/Metcalf–Brewington 98P/Takamizawa 99P/Kowal 100P/Hartley 101P/Chernykh 102P/Shoemaker After 1985 (notable) 103P/Hartley 105P/Singer Brewster 107P/Wilson–Harrington 109P/Swift–Tuttle 111P/Helin–Roman–Crockett 114P/Wiseman–Skiff 128P/Shoemaker–Holt 139P/Väisälä–Oterma 144P/Kushida 147P/Kushida–Muramatsu 153P/Ikeya–Zhang 163P/NEAT 168P/Hergenrother 169P/NEAT 177P/Barnard 178P/Hug–Bell 205P/Giacobini 209P/LINEAR 238P/Read 246P/NEAT 252P/LINEAR 255P/Levy 273P/Pons–Gambart 276P/Vorobjov 289P/Blanpain 311P/PANSTARRS 322P/SOHO 332P/Ikeya-Murakami 354P/LINEAR P/1997 B1 (Kobayashi) P/2010 B2 (WISE) P/2011 NO1 (Elenin) Comet-like asteroids 596 Scheila 2060 Chiron (95P) 4015 Wilson–Harrington (107P) 7968 Elst–Pizarro (133P) 165P/LINEAR 166P/NEAT 167P/CINEOS 60558 Echeclus (174P) 118401 LINEAR (176P) 238P/Read 259P/Garradd 311P/PANSTARRS 324P/La Sagra P/2010 A2 (LINEAR) P/2012 F5 (Gibbs) P/2012 T1 (PANSTARRS) P/2013 R3 (Catalina-PANSTARRS) (300163) 2006 VW139 Lost Recovered 11P/Tempel–Swift–LINEAR 15P/Finlay 17P/Holmes 27P/Crommelin 54P/de Vico–Swift–NEAT 55P/Tempel–Tuttle 57P/du Toit–Neujmin–Delporte 69P/Taylor 72P/Denning–Fujikawa 80P/Peters–Hartley 97P/Metcalf–Brewington 107P/Wilson–Harrington 109P/Swift–Tuttle 113P/Spitaler 122P/de Vico 157P/Tritton 177P/Barnard 205P/Giacobini 206P/Barnard–Boattini 271P/van Houten–Lemmon 273P/Pons–Gambart 289P/Blanpain Destroyed 3D/Biela 73P/Schwassmann–Wachmann D/1993 F2 (Shoemaker–Levy 9) Not found D/1770 L1 (Lexell) 5D/Brorsen 18D/Perrine–Mrkos 20D/Westphal 25D/Neujmin 34D/Gale 75D/Kohoutek 83D/Russell Visited by spacecraft 21P/Giacobini–Zinner (1985) 1P/Halley (1986) 26P/Grigg–Skjellerup (1992) 19P/Borrelly (2001) 81P/Wild (2004) 9P/Tempel (2005, 2011) C/2006 P1 (2007) 103P/Hartley (2010) 67P/Churyumov–Gerasimenko (2014) Non-Periodic comets (notable) Until 1910 C/-43 K1 (Caesar's Comet) X/1106 C1 (Great Comet of 1106) C/1577 V1 (Great Comet of 1577) C/1652 Y1 C/1680 V1 (Great Comet of 1680, Kirsch's Comet, Newton's Comet)) C/1702 H1 (Comet of 1702) C/1729 P1 (Comet of 1729, Comet Sarabat) C/1743 X1 (Great Comet of 1744, Comet Klinkenberg-Chéseaux) C/1760 A1 (Great Comet of 1760) C/1769 P1 (Great Comet of 1769) C/1807 R1 (Great Comet of 1807) C/1811 F1 (Great Comet of 1811) C/1819 N1 (Great Comet of 1819) C/1823 Y1 (Great Comet of 1823) C/1843 D1 (Great March Comet of 1843) C/1847 T1 (Miss Mitchell's Comet) C/1858 L1 (Comet Donati) C/1861 G1 (Comet Thatcher) C/1861 J1 (Great Comet of 1861) C/1865 B1 (Great Southern Comet of 1865) X/1872 X1 (Pogson's Comet) C/1874 H1 (Comet Coggia) C/1881 K1 (Comet Tebbutt) C/1882 R1 (Great Comet of 1882) C/1887 B1 (Great Southern Comet of 1887) C/1890 V1 (Comet Zona) C/1901 G1 (Great Comet of 1901) C/1910 A1 (Great January Comet of 1910) After 1910 C/1911 O1 (Brooks) C/1911 S3 (Beljawsky) C/1927 X1 (Skjellerup–Maristany) C/1931 P1 (Ryves) C/1941 B2 (de Kock-Paraskevopoulos) C/1947 X1 (Southern Comet) C/1948 V1 (Eclipse) C/1956 R1 (Arend–Roland) C/1957 P1 (Mrkos) C/1961 O1 (Wilson-Hubbard) C/1961 R1 (Humason) C/1962 C1 (Seki-Lines) C/1963 R1 (Pereyra) C/1965 S1 (Ikeya-Seki) C/1969 Y1 (Bennett) C/1970 K1 (White–Ortiz–Bolelli) C/1973 E1 (Kohoutek) C/1975 V1 (West) C/1980 E1 (Bowell) C/1983 H1 (IRAS–Araki–Alcock) C/1989 X1 (Austin) C/1989 Y1 (Skorichenko–George) C/1992 J1 (Spacewatch–Rabinowitz) C/1993 Y1 (McNaught–Russell) C/1995 O1 (Hale–Bopp) C/1996 B2 (Hyakutake) C/1997 L1 (Zhu–Balam) C/1998 H1 (Stonehouse) C/1998 J1 (SOHO) C/1999 F1 (Catalina) C/1999 S4 (LINEAR) C/2000 U5 (LINEAR) C/2000 W1 (Utsunomiya-Jones) C/2001 OG108 (LONEOS) C/2001 Q4 (NEAT) C/2002 T7 (LINEAR) C/2004 F4 (Bradfield) C/2004 Q2 (Machholz) C/2006 A1 (Pojmański) C/2006 M4 (SWAN) C/2006 P1 (McNaught) C/2007 E2 (Lovejoy) C/2007 F1 (LONEOS) C/2007 K5 (Lovejoy) C/2007 N3 (Lulin) C/2007 Q3 (Siding Spring) C/2007 W1 (Boattini) C/2008 Q1 (Matičič) C/2009 F6 (Yi–SWAN) C/2009 R1 (McNaught) C/2010 X1 (Elenin) C/2011 L4 (PANSTARRS) C/2011 W3 (Lovejoy) C/2012 E2 (SWAN) C/2012 F6 (Lemmon) C/2012 K1 (PANSTARRS) C/2012 S1 (ISON) C/2012 S4 (PANSTARRS) C/2013 A1 (Siding Spring) C/2013 R1 (Lovejoy) C/2013 US10 (Catalina) C/2013 V5 (Oukaimeden) C/2014 E2 (Jacques) C/2014 Q2 (Lovejoy) C/2015 V2 (Johnson) After 1910 (by name) Arend–Roland Austin Beljawsky Bennett Boattini Bowell Bradfield Brooks Catalina C/1999 F1 C/2013 US10 de Kock–Paraskevopoulos Eclipse Elenin Hale-Bopp Humason Hyakutake Ikeya-Seki IRAS–Araki–Alcock ISON Jacques Johnson Kohoutek Lemmon LINEAR C/1999 S4 C/2000 U5 C/2002 T7 LONEOS C/2001 OG108 C/2007 F1 Lovejoy C/2007 E2 C/2007 K5 C/2011 W3 C/2013 R1 C/2014 Q2 Lulin Machholz Matičič McNaught C/2006 P1 C/2009 R1 McNaught–Russell Mrkos NEAT Oukaimeden Pan-STARRS C/2011 L4 C/2012 K1 C/2012 S4 311P Pereyra Pojmański Ryves Seki–Lines Siding Spring C/2007 Q3 C/2013 A1 Skjellerup–Maristany Skorichenko–George SOHO Southern Spacewatch–Rabinowitz Stonehouse SWAN C/2006 M4 C/2012 E2 Utsunomiya–Jones West White–Ortiz–Bolelli Wilson–Hubbard Yi–SWAN Zhu–Balam
Category Commons Wikinews

Modern impact events
On Earth	Pre-2000 1490 Ch'ing-yang 1783 Great Meteor 1860 Great Meteor 1908 Tunguska 1913 Great Meteor Procession 1930 Curuçá River 1938 Chicora meteor 1947 Sikhote-Alin meteorite 1969 Murchison meteorite 1972 Great Daylight Fireball 1990 Earth-grazing meteoroid Post-2000 2002 Eastern Mediterranean 2002 Vitim 2007 Carancas 2008 TC3 impact 2009 Sulawesi superbolide 2012 Sutter's Mill meteorite 2012 UK meteoroid 2012 Novato meteorite 2013 Chelyabinsk meteor Chelyabinsk meteorite 2014 AA impact 2014 Ontario fireball 2015 Kerala meteorite 2015 Thailand bolide WT1190F impact
On Jupiter	1994 Comet Shoemaker–Levy 9 2009 Jupiter impact 2010 Jupiter impact
Lists	Asteroid close approaches to Earth Comets Bolides Meteor air bursts Meteorite falls Minor planets crossing Earth's orbit
See also	Asteroid impact avoidance Bolide Earth-grazing fireball Meteor procession Meteor shower Meteorite Meteoroid Near-Earth object Potentially hazardous object

Jupiter   (outline)
Geography	Atmosphere Great Red Spot Diamonds Magnetosphere Rings
Moons	Inner moons Adrastea Amalthea Metis Thebe Galilean moons Callisto Europa Ganymede Io Irregular moons Ananke group Carme group Himalia group Pasiphae group Ungrouped moons Carpo Themisto S/2003 J 2 S/2003 J 12 S/2011 J 1
Astronomy	General Jupiter-crossing minor planets Solar eclipses Trojans Greek camp Trojan camp Impact events Comet Shoemaker–Levy 9 2009 Jupiter impact event 2010 Jupiter impact event
Exploration and orbiting missions	Current Juno Past Cassini Galileo New Horizons Pioneer program Pioneer 10 Pioneer 11 Ulysses Voyager program Voyager 1 Voyager 2 Future Jupiter Icy Moons Explorer (2022) Europa Clipper (2025) Proposed Io Volcano Observer (2021) Laplace-P (2023) Smara (2030)
Related	Fiction Jovian Jupiter Moons Mythology
Book Category Portal