Impact events on Jupiter
In modern times, numerous impact events on Jupiter have been observed, the most significant of which was the collision of Comet Shoemaker–Levy 9 in 1994. Jupiter is the most massive planet in the Solar System and thus has a vast sphere of gravitational influence, the region of space where an asteroid capture can take place under favorable conditions.
Jupiter is often able to capture comets that orbit the Sun; such comets enter unstable orbits around the planet that are highly elliptical and perturbable by solar gravity. While some of them eventually recover a heliocentric orbit, others crash into the planet or more rarely become one of its satellites.
In addition to the mass factor, Jupiter's relative proximity to the inner Solar System allows it to influence the distribution of minor bodies there. Dynamic studies have shown that the presence of Jupiter tends to reduce the frequency of impacts on the Earth of objects coming from the Oort cloud, while it increases the number of impacts of asteroids and short-period comets.
For these reasons Jupiter has the highest frequency of impacts of any planet in the Solar System, justifying its reputation as the "sweeper" or "cosmic vacuum cleaner" of the Solar System. 2018 studies estimate that between 10 and 65 impacts per year of meteoroids with a diameter of between can occur on the planet. For larger objects capable of leaving a visible scar on the planet's cloud cover for weeks, that study gives an impact frequency of one every 2–12 years. Even larger objects would strike Jupiter every 6–30 years. 2009 studies suggest an impact frequency of once every 50–350 years for an object of between in diameter; hits from smaller objects would occur more frequently. A 1997 study estimated comets in diameter collide with Jupiter once in approximately 500 years and those in diameter do so once in every 6,000 years.
About Jupiter
Jupiter is a gas giant planet with no solid surface; the lowest atmospheric layer, the troposphere, gradually changes into the planet's inner layers. The impacts of comets and asteroids generate debris fields that are progressively masked by the action of the winds, and whose significance depends upon the size of the impacting object. Human knowledge of such impacts is dependent upon direct and almost immediate observation of the event itself or of the phenomena associated with it.The cratered surfaces of Jupiter's major satellites provide information about the most ancient epochs. In particular, the discovery by the Voyager missions of thirteen crater chains on Callisto and three on Ganymede, and the evidence of the impact of Comet Shoemaker–Levy 9, provide consistent evidence of ancient fragmentation of comets and their impacts with Jupiter and its moons. While the chains of craters observed on Earth's moon often radiate from major craters and are commonly believed to have been created by secondary impacts of the material ejected from the main collision, those present on the Jovian moons are not connected to a main crater, and it is likely they were created by the impact of a series of cometary fragments.
The first evidence of impacts on Jupiter was found in the 17th century. Japanese amateur astronomer Isshi Tabe discovered among the correspondence of Giovanni Cassini's observations some drawings representing a dark spot that appeared on Jupiter on December 5, 1690, and follow its evolution over 18 days. This finding could constitute evidence of the observation of an impact on Jupiter prior to that of SL9.
Impact events
1979 impact
The impact of a meteoroid on Jupiter was first captured on March 5, 1979, 17:45:24 UTC by the Voyager 1 spacecraft, which recorded a rapid flicker of light in the planet's atmosphere. Cook and Duxbury estimated that the mass of the meteoroid was about 11 kg.1994 impacts
On July 16, 1994, the first of a series of fragments of the comet Shoemaker–Levy 9, which had broken up two years earlier, impacted Jupiter's atmosphere. The impacts had been predicted well in advance and were therefore observed by terrestrial telescopes and several space observatories, including the Hubble Space Telescope, the ROSAT X-ray-observing satellite, the W. M. Keck Observatory, and the Galileo spacecraft, which was then en route to Jupiter with a scheduled arrival in 1995. Although the impacts took place on the side of Jupiter hidden from Earth, Galileo, then at a distance of 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.Two other space probes observed the impact; the Ulysses spacecraft, primarily designed for solar observations, was pointed towards Jupiter from its location away, and Voyager 2, which was then from Jupiter, was programmed to look for radio emissions in the 1–390 kHz range and make observations with its ultraviolet spectrometer.
Astronomer Ian Morison described the impacts as following:
The first impact occurred at 20:13 UTC on July 16, 1994, when fragment A of the comet nucleus| nucleus slammed into Jupiter's southern hemisphere at about. Instruments on Galileo detected a fireball that reached a peak temperature of about, compared to the typical Jovian cloud-top temperature of about. It than expanded and cooled rapidly to about. The plume from the fireball quickly reached a height of over and was observed by the HST.
A few minutes after the fireball was detected, Galileo measured renewed heating, which was probably caused by ejected material falling back into the planet. Earth-based observers detected the fireball rising over the limb of the planet shortly after the initial impact.
Despite published predictions, astronomers had not expected to see fireballs from the impacts, and did not know how visible the other atmospheric effects of the impacts would be from Earth. Observers saw a huge dark spot appear after the first impact. The spot was visible from Earth; 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.
Over the next six days, 21 distinct impacts were observed, the largest of which occurred on July 18 at 07:33 UTC when fragment G struck Jupiter. This impact created a large, dark spot over —almost one Earth diameter across—and was estimated to have released an energy equivalent to six million megatons of TNT. On July 19, two impacts 12 hours apart created impact marks of similar size to that caused by fragment G. Impacts continued until July 22, when fragment W struck the planet.
2009 impact
On July 19, 2009, amateur astronomer Anthony Wesley discovered a new black spot about the size of Earth in Jupiter's southern hemisphere. Thermal infrared analysis showed it was warm and spectroscopic methods detected ammonia. The impact was studied by NASA's Hubble Space Telescope. According to Hueso et al., the impact was caused by "a icy or by a rocky object"; a 4800-km debris field was created by the impact; researchers noted that it was "dark in the visible and bright in methane absorption bands, and observable for several months using amateur telescopes and for a minimum of six months with professional ones".2010 impacts
An impact event that occurred on June 3, 2010 involved an object estimated at between, and was recorded and first reported by Anthony Wesley. The impact was also captured on video in the Philippines by amateur astronomer Christopher Go.On August 20, 2010 another impact was detected independently by Japanese amateur astronomers Masayuki Tachikawa and by Kazuo Aoki and Masayuki Ishimaru. The region of impact did not show any presence of debris field, so the impactor was a small body.
2012 impact
On September 10, 2012 at 11:35 UTC, amateur astronomer Dan Petersen, using a Meade 12" LX200 telescope, saw a fireball on Jupiter that lasted between one and two seconds. George Hall had been recording Jupiter with a webcam on his 12" Meade; upon hearing the news, Hall checked the video to see whether the impact was captured. Hall had captured a four-second clip of the impact and released the video to the public. The impact's estimated position on Jupiter was longitude 345° and latitude 2°. Planetary scientist Michael H. Wong estimated the fireball was created by a meteoroid less than in diameter. Several collisions of this size may happen on Jupiter each year. The 2012 impact was the fifth observed on Jupiter, and the fourth such event between 2009 and 2012. It was similar to the flash observed on August 20, 2010.2016–2020 impacts
On March 17, 2016, an impact fireball on Jupiter's limb was recorded by Gerrit Kernbauer using an telescope operating at f/15 in Moedling, Austria. This report was later confirmed by an independent observation by amateur John McKeon. The size of the impacting object was estimated to be between.On May 26, 2017, amateur astronomer Sauveur Pedranghelu in Corsica, France observed a flash on Jupiter. The event was announced the next day; German amateur astronomers Thomas Riessler and André Fleckstein confirmed it. The impactor had an estimated size of between.
On April 10, 2020, the Juno spacecraft observed a fireball on Jupiter that was consistent with the impact of a meteor. It was the first fireball to be detected by Juno. Researchers estimate Jupiter experiences approximately 24,000 impact events of this size per year—around 2.7 per hour.
2021−2023 impacts
At 22:39:27 UTC on September 13, 2021, Brazilian amateur astronomer José Luis Pereira reported the observation of a bright spot on Jupiter lasting for two seconds. Two astronomers from France and Germany confirmed the observation, suggesting an impact event likely caused by a small asteroid or comet around in diameter. An image taken by astrophotographer Damian Peach one hour after the impact showed no aftermath.Another impact was observed on 13:24 UTC on October 15, 2021. The flare was discovered by a team led by amateur astronomer Ko Arimatsu of Kyoto University using a system called PONCOTS that is a part of the Organized Autotelescopes for Serendipitous Event Survey.
On 28 August 2023, a fireball, likely an asteroid, impacting Jupiter was video recorded by astronomers.