Impact events on Jupiter
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.
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.
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.
[15] 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.
This impact created a large, dark spot over 12,000 km or 7,500 mi[42][43]—almost one Earth diameter across—and was estimated to have released an energy equivalent to six million megatons of TNT.
[45] On July 19, 2009, amateur astronomer Anthony Wesley discovered a new black spot about the size of Earth in Jupiter's southern hemisphere.
[50] An impact event that occurred on June 3, 2010 involved an object estimated at between 8 and 13 meters (26 and 43 ft), and was recorded and first reported by Anthony Wesley.
[55][56] On March 17, 2016, an impact fireball on Jupiter's limb was recorded by Gerrit Kernbauer using an 8-inch (20 cm) telescope operating at f/15 in Moedling, Austria.
[22] 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.
[60] Two astronomers from France and Germany confirmed the observation, suggesting an impact event likely caused by a small asteroid or comet around 100 m (330 ft) in diameter.
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 (OASES).
[64] A large part of the kinetic energy of the impacting object is transferred to the atmosphere, causing a rapid increase in the local temperature, which is associated with an intense light emission.
In the case of the SL9 impacts, ammonia and carbon disulfide, which are typically present in the troposphere, remained in the upper atmosphere for at least 14 months after the event.
[66] Collisions can also generate seismic waves, which in the case of SL9 traveled across the planet at a speed of 450 meters per second (1,500 ft/s) and were observed for more than two hours after the impact.
[67] In some cases, aurorae may appear near the impact site and at the antipodal zone, evaluated with respect to Jupiter's magnetic field and interpreted as a consequence of the fallout of the plume material.
[68] In the case of the impacts of SL9, a marked increase in radio emissions from Jupiter was detected; this was interpreted as a consequence of the introduction of relativistic electrons into the planet's magnetosphere.
The identification of specific chemical species through spectroscopic analysis of the debris makes it possible to distinguish a comet, which are rich in water and poor in silicon, from an asteroid.
[74] The distribution of meteoroids in the outer Solar System is not known and therefore it is not possible to provide a forecast on the frequency of impact without relying on partial data.
For larger objects capable of leaving a visible scar on the planet's cloud cover for weeks, he provides an impact frequency of one every 2–12 years.
[22] From the observation of the impact events on Jupiter, it is possible to deduce information on the composition of comets and asteroids, and the deeper layers of the Jovian atmosphere.
[74] In the case of the meteoroids that do not leave evident impact marks, the light emission that accompanies the atmospheric entry lasts for between one and two seconds, and a continuous monitoring of the planet's surface at high frame rate is necessary for their identification.
[63] More information on the frequency of impact can be obtained by analyzing the historical observations of Jupiter conducted in the 18th and 19th centuries in the light of the new knowledge acquired.
[79] In 2007, some studies related the ripples of Jupiter's rings to the impact of SL9 by analyzing the time evolution recorded by the instruments on board the Galileo, Cassini, and New Horizons probes that visited the planet.
Astronomers have speculated that without Jupiter to mop up potential Earth impactors, extinction events might have been more frequent and complex life might not have been able to develop.
[89][90][91] In 2009, it was shown the presence of a smaller planet at Jupiter's position in the Solar System might significantly increase the impact rate of comets on Earth.
A planet of Jupiter's mass seems to provide increased protection against asteroids but the total effect on all orbital bodies within the Solar System is unclear.
[92][93][94] Dynamic studies have shown that the presence of Jupiter tends to reduce the frequency of impact on the Earth of objects coming from the Oort cloud, though the authors noted that "near-Earth objects (some of which come from the asteroid belt, others from the short-period comet population) pose a far greater threat to the Earth than that posed by the Oort cloud comets".
Among the forms of communication aimed at the general public were the 1998 films Deep Impact by Mimi Leder and Armageddon by Michael Bay.
[99] The role played by non-professional astronomers in identifying the signs of impact is also significant, thanks to a reduction in the cost of advanced observation instruments.
