Date | July 19, 2009 |
---|---|
Location | Jupiter |
The 2009 Jupiter impact event, occasionally referred to as the Wesley impact, was a July 2009 impact event on Jupiter that caused a black spot in the planet's atmosphere. The impact area covered 190 million square kilometers, similar in area to the planet's Little Red Spot and approximately the size of the Pacific Ocean. [3] The impactor is estimated to have been about 200 to 500 meters in diameter. [4] (For comparison, the one for the Tunguska event was estimated to be in the 60–190 meters range.)
Amateur astronomer Anthony Wesley discovered the impact at approximately 13:30 UTC on 19 July 2009 (exactly 15 years after the Jupiter impacts of comet Shoemaker–Levy 9, or SL9). He was at his home observatory just outside Murrumbateman, New South Wales, Australia, using stacked images on a 14.5-inch (36.8 cm) diameter reflecting telescope equipped with a low light machine vision video camera attached to the telescope. [5] Wesley stated that:
When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I [thought] likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions improved I suddenly realised that it wasn't just dark, it was black in all channels, meaning it was truly a black spot. [6]
Wesley sent an e-mail to others including the NASA Jet Propulsion Laboratory in Pasadena, California reporting his observations. [7]
Paul Kalas and collaborators confirmed the sighting. They had time on the Keck II telescope in Hawaii, and had been planning to observe Fomalhaut b, but they spent some of their time looking at the Jupiter impact. [8] Infrared observation by Keck and the NASA Infrared Telescope Facility (IRTF) [3] at Mauna Kea showed a bright spot where the impact took place, indicating the impact warmed a 190 million square km area of the lower atmosphere at 305° west, 57° south near Jupiter's south pole. [3]
The spot's prominence indicated that it was composed of high-altitude aerosols similar to those seen during the SL9 impact. [8] Using near-infrared wavelengths and the IRTF, Glenn Orton and his team detected bright upwelling particles in the planet's upper atmosphere and using mid-infrared wavelengths, found possible extra emission of ammonia gas. [9]
The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Tunguska River Valley in Siberia in June 1908. [2] (This would be approximately 12,500–13,000 megatons of TNT, over a million times more powerful than the bomb dropped on Hiroshima). [10]
The object that hit Jupiter was not identified before Wesley discovered the impact. A 2003 paper estimated comets with a diameter larger than 1.5 kilometers impact Jupiter about every 90 to 500 years, [11] while a 1997 survey suggested that the astronomer Cassini may have recorded an impact in 1690. [12]
Given the size of the SL9 impactors, [13] it is likely that this object was less than one kilometer in diameter. [2] [14] Finding water at the site would indicate that the impactor was a comet, [15] as opposed to an asteroid or a very small, icy moon. [16] At first it was believed that the object was more likely to be a comet since comets generally have more planet-crossing orbits. [17] At the distance of Jupiter (5.2 AU) most small comets are not close enough to the Sun to be very active, and so would be hard to detect. [17] Small kilometer-sized asteroids would also be hard to detect, however, and recent work by Orton et al. and Hammel et al. has strongly suggested the impactor was an asteroid, as it left only one impact site, did not reduce Jovian decametric radiation emission by contributing significant dust to the Jovian magnetosphere, and produced high altitude dusty debris full of silica, very different than what was produced by SL9.[ citation needed ]
As of 2012, the impactor is believed to have been an asteroid with a diameter of about 200 to 500 meters. [4]
Assuming it was an inactive comet (or asteroid) about 1 km in diameter, this object would have been no brighter than about apparent magnitude 25. [17] (Jupiter shines about 130 billion times brighter than a 25th magnitude object.) [18] Most asteroid surveys which use a wide field of view do not see fainter than about magnitude 22 (which is 16x brighter than magnitude 25). [17] Even detecting satellites less than 10 km in diameter orbiting Jupiter is difficult and requires some of the best telescopes in the world. [19] It is only since 1999 with the discovery of Callirrhoe that astronomers have been able to discover many of Jupiter's smallest moons. [20]
An asteroid is a minor planet—an object that is neither a true planet nor a comet—that orbits within the inner Solar System. They are rocky, metallic, or icy bodies with no atmosphere. The size and shape of asteroids vary significantly, ranging from small rubble piles under a kilometer across to Ceres, a dwarf planet almost 1000 km in diameter.
Comet Shoemaker–Levy 9 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. 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.
A near-Earth object (NEO) is any small Solar System body whose orbit around the Sun can bring it near the Earth. By convention, a small natural Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, as the impacting body is usually traveling at several kilometres a second, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.
Tempel 1 is a periodic Jupiter-family comet discovered by Wilhelm Tempel in 1867. It completes an orbit of the Sun every 5.6 years. Tempel 1 was the target of the Deep Impact space mission, which photographed a deliberate high-speed impact upon the comet in 2005. It was re-visited by the Stardust spacecraft on February 14, 2011, and came back to perihelion in August 2016. On 26 May 2024, it will make a modest approach of 0.55 AU to Jupiter which will lift the perihelion distance and 9P will next come to perihelion on 12 February 2028 when it will be 1.77 AU from the Sun.
617 Patroclus is a large binary Jupiter trojan asteroid. It is a dark D-type asteroid and a slow rotator, due to the 103-hour orbital period of its two components. It is one of five Jupiter trojan asteroids targeted by the Lucy space probe, and is scheduled for a flyby in 2033.
Wide-field Infrared Survey Explorer is a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009. WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid. WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a 40 cm (16 in) diameter infrared telescope in Earth orbit.
2007 WD5 is an Apollo asteroid some 50 m (160 ft) in diameter and a Mars-crosser asteroid first observed on 20 November 2007, by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance of colliding with Mars on 30 January 2008. However, by 9 January 2008, additional observations allowed NASA's Near Earth Object Program (NEOP) to reduce the uncertainty region resulting in only a 1-in-10,000 chance of impact. 2007 WD5 most likely passed Mars at a distance of 6.5 Mars radii. Due to this relatively small distance and the uncertainty level of the prior observations, the gravitational effects of Mars on its trajectory are unknown and, according to Steven Chesley of NASA's Jet Propulsion Laboratory Near-Earth Object program, 2007 WD5 is currently considered 'lost' (see lost asteroids).
Heidi B. Hammel is a planetary astronomer who has extensively studied Neptune and Uranus. She was part of the team imaging Neptune from Voyager 2 in 1989. She led the team using the Hubble Space Telescope to view Shoemaker-Levy 9's impact with Jupiter in 1994. She has used the Hubble Space Telescope and the Keck Telescope to study Uranus and Neptune, discovering new information about dark spots, planetary storms and Uranus' rings. In 2002, she was selected as an interdisciplinary scientist for the James Webb Space Telescope.
The 2010 Jupiter impact event was a bolide impact event on Jupiter by an object estimated to be about 8–13 metres (26–43 ft) in diameter. The impactor may have been an asteroid, comet, centaur, extinct comet, or temporary satellite capture.
238P/Read is a main-belt comet discovered on 24 October 2005 by astronomer Michael T. Read using the Spacewatch 36-inch telescope on Kitt Peak National Observatory. It has an orbit within the asteroid belt and has displayed the coma of a traditional comet. It fits the definition of an Encke-type comet with.
NEO Surveyor, formerly called Near-Earth Object Camera (NEOCam), then NEO Surveillance Mission, is a planned space-based infrared telescope designed to survey the Solar System for potentially hazardous asteroids.
Anthony Wesley is an Australian computer programmer and amateur astronomer, known for his discoveries of the 2009 and 2010 Jupiter impact events.
C/2013 UQ4 (Catalina) is a Solar System comet that came close to the Earth on July 10, 2014, at a distance of 0.314 AU (47,000,000 km; 29,200,000 mi).
460P/PanSTARRS (also known with the provisional designation P/2016 BA14) is a near-Earth object and periodic comet of the Jupiter family, with an orbital period of 5.25 years. In March 2016 it passed at distance of 2.2 million miles (3.5 million km, or 9 lunar distances) from Earth. It was the closest approach by a comet since 1770 and 3rd closest recorded comet to Earth. The close flyby enabled the size of the nucleus to be calculated at about 1 km (0.62 mi) in diameter, which was much bigger than expected. The comet is very dark, reflecting about 2-3 percent of the visible light, about the same as a charcoal briquette. It has a very similar orbit as numbered comet 252P/LINEAR, and may be related to it (e.g. split off of).
An astronomical body collided with Jupiter, the largest planet in the Solar System, on March 17, 2016. The object in question has not been confirmed by NASA to be an asteroid or comet, but may be so.
Asteroid impact prediction is the prediction of the dates and times of asteroids impacting Earth, along with the locations and severities of the impacts.
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.
P/2013 R3 (Catalina–PanSTARRS) was an active main-belt asteroid that disintegrated from 2013 to 2014 due to the centrifugal breakup of its rapidly-rotating nucleus. It was discovered by astronomers of the Catalina and Pan-STARRS sky surveys on 15 September 2013. The disintegration of this asteroid ejected numerous fragments and dusty debris into space, which temporarily gave it a diffuse, comet-like appearance with a dust tail blown back by solar radiation pressure. Observations by ground-based telescopes in October 2013 revealed that P/2013 R3 had broken up into four major components, with later Hubble Space Telescope observations showing that these components have further broken up into at least thirteen smaller fragments ranging 100–400 meters (330–1,310 ft) in diameter. P/2013 R3 was never seen again after February 2014.
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: CS1 maint: bot: original URL status unknown (link). Accessed 2009-07-27. 2009-07-29.1.5-km-diameter comets is currently N(d > 1.5 km) = 0.005+0.006
−0.003 per annum
Jupiter has been continuously monitored for almost 400 yr