What is the largest asteroid?
Ceres (dwarf planet)
Ceres is the largest object in the asteroid belt.
It is sometimes assumed that Ceres has been "re"classified as a dwarf planet, and that it is therefore no longer considered an asteroid. For example, a news update at Space.com spoke of "Pallas, the largest asteroid, and Ceres, the dwarf planet formerly classified as an asteroid", whereas an IAU question-and-answer posting states, "Ceres is (or now we can say it was) the largest asteroid", though it then speaks of "other asteroids" crossing Ceres' path and otherwise implies that Ceres is still considered an asteroid. The Minor Planet Center notes that such bodies may have dual designations. The 2006 IAU decision that classified Ceres as a dwarf planet never addressed whether it is or is not an asteroid. Indeed, the IAU has never defined the word 'asteroid' at all, having preferred the term 'minor planet' until 2006, and preferring the terms 'small Solar System body' and 'dwarf planet' after 2006. Lang (2011) comments "the [IAU has] added a new designation to Ceres, classifying it as a dwarf planet. ... By [its] definition, Eris, Haumea, Makemake and Pluto, as well as the largest asteroid, 1 Ceres, are all dwarf planets", and describes it elsewhere as "the dwarf planet–asteroid 1 Ceres". NASA continues to refer to Ceres as an asteroid, as do various academic textbooks.
Asteroid
Hygiea is the largest carbonaceous asteroid and, unlike the other largest asteroids, lies relatively close to the plane of the ecliptic. It is the largest member and presumed parent body of the Hygiean family of asteroids.
13241 Biyo
The asteroid has not been surveyed by none of the space-based telescopes, such as the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer. The "Collaborative Asteroid Lightcurve Link" assumes an albedo for a stony asteroid of 0.24 – derived from 8 Flora, the largest member and namesake of this orbital family – and calculates a diameter of 3.92 kilometers with an absolute magnitude of 14.2.
Near-Earth object
The second-largest observed impact after the Tunguska meteor was a 1.1-megaton air blast near the Prince Edward Islands off the coast of South Africa in 1963, which was detected only by infrasound sensors. The third-largest but most-observed impact was the Chelyabinsk meteor of February 15, 2013. A asteroid exploded with the equivalent blast yield of 400–500 kilotons. The calculated orbit of the pre-impact asteroid is similar to that of Apollo asteroid 2011 EO40, making the latter the meteor's possible parent body.
14627 Emilkowalski
"Emilkowalski" is the biggest member and namesake of a collisional group of asteroids, that resulted from the destruction of a larger parent body. The disruption happened approximately 220,000 years ago and it is one of the most recent asteroid breakups discovered in the main belt. The recently formed stony Emilkowalski family (family identification number: 523) consist of only 4 identified members. The other members are , and .
2018 GE3
It was the 32nd known asteroid to flyby Earth within 1 lunar distance (LD) since the start of 2018 and 16th closest, although it was the largest known asteroid to pass within half a lunar distance. After closest approach its apparent magnitude dropped from 12 to 35 in less than 12 hours, heading towards the Sun. Coming from the opposite direction, it would have been impossible to observe before its approach. A preliminary analysis of the orbit of shows that this is the closest this particular asteroid has come to Earth since at least 1930.
253 Mathilde
Mathilde was visited by the NEAR Shoemaker spacecraft during June 1997, on its way to asteroid 433 Eros. During the flyby, the spacecraft imaged a hemisphere of the asteroid, revealing many large craters that had gouged out depressions in the surface. It was the first carbonaceous asteroid to be explored and, until 21 Lutetia was visited in 2010, was the largest asteroid to be visited by a spacecraft.
Asteroid
In October 2013, water was detected on an extrasolar body for the first time, on an asteroid orbiting the white dwarf GD 61. On 22 January 2014, European Space Agency (ESA) scientists reported the detection, for the first definitive time, of water vapor on Ceres, the largest object in the asteroid belt. The detection was made by using the far-infrared abilities of the Herschel Space Observatory. The finding is unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids." In May 2016, significant asteroid data arising from the Wide-field Infrared Survey Explorer and NEOWISE missions have been questioned. Although the early original criticism had not undergone peer review, a more recent peer-reviewed study was subsequently published.
Eunomia family
By far the largest member is 15 Eunomia, the largest of all the "stony" S-type asteroid, It is about 300 km across along its longest axis, has a 250 km mean radius, and lies close to the barycenter of the family. Eunomia has been estimated to contain about 70–75% of the matter from the original parent body. This had a mean diameter of about 280 km and was disrupted by the catastrophic impact that created the family. It is likely that the parent body was at least partly differentiated, because the surface of Eunomia and spectra of the smaller family members show some variation. This notwithstanding, other studies have indicated that the body that was definitively shattered by the impact that created the family was probably already somewhat fragmented by previous smaller collisions. The impactor was probably a smaller, yet still very substantial asteroid of 50 km diameter (or so) that hit at a speed of about 22,000 km/h.
M-type asteroid
16 Psyche is the largest M-type asteroid, and does appear to be metallic. 21 Lutetia, an anomalous, probably non-metallic body, was the first M-type asteroid to be imaged by a spacecraft when the Rosetta space probe visited it on July 10, 2010. Another M-type asteroid, 216 Kleopatra, was imaged by radar by the Arecibo Observatory in Puerto Rico, and has a dog bone-like shape.
S-type asteroid
S-types asteroids, with an astronomical albedo of typically 0.20, are moderately bright and consist mainly of iron- and magnesium-silicates. They are dominant in the inner part of the asteroid belt within 2.2 AU, common in the central belt within about 3 AU, but become rare farther out. The largest is 15 Eunomia (about 330 km wide across its longest dimension), with the next largest members by diameter being 3 Juno, 29 Amphitrite, 532 Herculina and 7 Iris. These largest S-types are visible in 10x50 binoculars at most oppositions; the brightest, 7 Iris, can occasionally become brighter than +7.0, which is a higher magnitude than any asteroid except the unusually reflective 4 Vesta.
94 Aurora
Aurora (minor planet designation: 94 Aurora) is one of the largest main-belt asteroids. With an albedo of only 0.04, it is darker than soot, and has a primitive compositions consisting of carbonaceous material. It was discovered by J. C. Watson on September 6, 1867, in Ann Arbor, and named after Aurora, the Roman goddess of the dawn.
51824 Mikeanderson
"Mikeanderson" is a member the Eos family (), the largest asteroid family in the outer asteroid belt consisting of nearly 10,000 asteroids. It orbits the Sun in the outer main-belt at a distance of 2.7–3.3 AU once every 5 years and 3 months (1,903 days; semi-major axis of 3.01 AU). Its orbit has an eccentricity of 0.11 and an inclination of 10° with respect to the ecliptic.
Tunguska event
The Tunguska event is the largest impact event on Earth in recorded history. Studies have yielded different estimates of the meteoroid's size, on the order of , depending on whether the body was a comet or a denser asteroid.
Armageddon (1998 film)
In an interview with "Entertainment Weekly", Bay admitted that the film's central premise "that NASA could actually do something in a situation like this" was unrealistic. However, the largest known Potentially Hazardous Asteroid(PHA) is (53319) 1999 JM8 which is actually only 7 km in diameter. Additionally, near the end of the credits, there is a disclaimer stating, "The National Aeronautics and Space Administration's cooperation and assistance does not reflect an endorsement of the contents of the film or the treatment of the characters depicted therein."
Asteroid belt
On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres, the largest object in the asteroid belt. The detection was made by using the far-infrared abilities of the Herschel Space Observatory. The finding was unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."
31 Euphrosyne
The mass estimate of Euphrosyne in Baer (2011) makes it apparently the 5th-most-massive asteroid, coming after only the "big four". It also has the highest estimated density, indicating that it is a solid body like the other largest asteroids. However, all large asteroids with comparable densities (16 Psyche and 532 Herculina) have very large uncertainties, so both the mass and density are likely to be lower than the median estimate.
(4953) 1990 MU
(4953) 1990 MU is a large Earth-crossing asteroid (ECA) belonging to the Apollo family of asteroids which also cross the orbits of Mars and Venus. At approximately 3 km in diameter, it is one of the largest known ECAs. is the asteroid's temporary discovery name. It has now been assigned a permanent number from the Minor Planet Center (4953) indicating that its orbit has been confirmed, but has not (at least so far) been assigned a name. Only a small fraction of asteroids have been named.
Allende meteorite
The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After breaking up in the atmosphere, an extensive search for pieces was conducted and over 2 tonnes (tons) of meteorite were recovered. The availability of large quantities of samples of the scientifically-important chondrite class has enabled numerous investigations by a large number of scientists; it is often described as "the best-studied meteorite in history." The Allende meteorite has abundant, large calcium-aluminium-rich inclusions, which are among the oldest objects formed in the Solar System.
Space exploration
Until the advent of space travel, objects in the asteroid belt were merely pinpricks of light in even the largest telescopes, their shapes and terrain remaining a mystery.
Several asteroids have now been visited by probes, the first of which was "Galileo", which flew past two: 951 Gaspra in 1991, followed by 243 Ida in 1993. Both of these lay near enough to "Galileo"'s planned trajectory to Jupiter that they could be visited at acceptable cost. The first landing on an asteroid was performed by the "NEAR Shoemaker" probe in 2000, following an orbital survey of the object. The dwarf planet Ceres and the asteroid 4 Vesta, two of the three largest asteroids, were visited by NASA's "Dawn" spacecraft, launched in 2007.
10 Hygiea
Hygiea (minor planet designation: 10 Hygiea) is the fourth-largest asteroid in the Solar System by volume and mass, and it is located in the asteroid belt. With somewhat oblong diameters of and a mass estimated to be 2.9% of the total mass of the belt, it is the largest of the class of dark C-type asteroids with a carbonaceous surface.
Standard asteroid physical characteristics
Such estimates can be indicated as approximate by use of a tilde "~". Besides these "guesstimates", masses can be obtained for the larger asteroids by solving for the perturbations they cause in each other's orbits, or when the asteroid has an orbiting companion of known orbital radius. The masses of the largest asterois 1 Ceres, 2 Pallas, and 4 Vesta can also be obtained from perturbations of Mars.
While these perturbations are tiny, they can be accurately measured from radar ranging data from the Earth to spacecraft on the surface of Mars, such as the Viking landers.
Hungaria asteroid
The Hungaria group is a dynamical group of asteroids in the asteroid belt. The Hungaria asteroids orbit the Sun with a semi-major axis (longest radius of an ellipse) between 1.78 and 2.00 astronomical units (AU). They are the innermost dense concentration of asteroids in the Solar System—the near-Earth asteroids are much more sparse—and derive their name from their largest member 434 Hungaria. The Hungaria group includes the Hungaria family (), a collisional asteroid family which dominates its population.
3963 Paradzhanov
"Paradzhanov" is a member of the Nysa family (), the asteroid belt's largest asteroid family. The low-inclination family is located in the inner main-belt and named after 44 Nysa. It is better described as the "Nysa-Polana complex" because it consists of two albedo-groups and at least three collisional families: Nysa, Polana, Eulalia, named after 142 Polana and 495 Eulalia. These are difficult to distinguish as they are dynamically overlapping with different but varying albedos. "Paradzhanov" has a relatively high albedo "(see below)" which places it into the stony Nysian subgroup of the "Nysa-Polana complex".
16 Psyche
Psyche ( ; minor planet designation: 16 Psyche) is one of the ten most massive asteroids in the asteroid belt. It is over 200 km (120 mi) in diameter and contains a little less than 1% of the mass of the entire asteroid belt. It is thought to be the exposed iron core of a protoplanet. It is the most massive metallic M-type asteroid. Psyche was discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852 from Naples and named after the Greek mythological figure Psyche.
1169 Alwine
"Alwine" is a member of the Flora family (), a giant asteroid family and the largest family of stony asteroids in the main belt. It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.7 AU once every 3 years and 6 months (1,290 days; semi-major axis of 2.32 AU). Its orbit has an eccentricity of 0.15 and an inclination of 4° with respect to the ecliptic. As no precoveries were taken, and no prior identifications were made, "Alwine"s observation arc begins with its official discovery observation at Heidelberg in August 1930.
375 Ursula
Ursula, (minor planet designation: 375 Ursula) provisional designation , is a dark asteroid and parent body of the Ursula family from the outer regions of the asteroid belt. It is one of the largest asteroids with a diameter of approximately 200 kilometers. It was discovered on 18 September 1893, by French astronomer Auguste Charlois at Nice Observatory in France. The meaning of the asteroids's name is .
List of instrument-resolved minor planets
Because of their distance from Earth and their small dimension, minor planets such as asteroids represent a challenge for astronomical instruments to resolve. Even two of the largest objects in the asteroid belt, 2 Pallas and 4 Vesta, have maximum angular diameters of less than an arcsecond. With a ground-based optical telescope, resolution of these objects through the Earth's thick atmosphere can require techniques such as speckle interferometry or adaptive optics.
10 Hygiea
Hygiea is the main member of the Hygiea family and contains almost all the mass (well over 90%) in this family. It is the largest of the class of dark C-type asteroids that are dominant in the outer asteroid belt—which lie beyond the Kirkwood gap at 2.82 AU. Hygiea appears to have a noticeably oblate spheroid shape, with an average diameter of 444 ± 35 km and a semimajor axis ratio of 1.11. This is much more than for the other objects in the "big four"—2 Pallas, 4 Vesta and the dwarf planet Ceres. Aside from being the smallest of the four, Hygiea, like Ceres, has a relatively low density, which is more comparable to the icy satellites of Jupiter or Saturn than to the terrestrial planets or the stony asteroids.
Near-Earth object
In 1961, the IAU defined meteoroids as a class of solid interplanetary objects distinct from asteroids by their considerably smaller size. This definition was useful at the time because, with the exception of the Tunguska event, all historically observed meteors were produced by objects significantly smaller than the smallest asteroids observable by telescopes. As the distinction began to blur with the discovery of ever smaller asteroids and a greater variety of observed NEO impacts, revised definitions with size limits have been proposed from the 1990s. In April 2017, the IAU adopted a revised definition that generally limits meteoroids to a size between 30 µm and 1 m in diameter, but permits the use of the term for any object of any size that caused a meteor, thus leaving the distinction between asteroid and meteoroid blurred.
4954 Eric
It is the largest near-Earth asteroid discovered since 3552 Don Quixote in 1983. On 2007 October 11 the asteroid passed from Earth. It currently makes closer approaches to Mars than it does Earth. The asteroid has a rotation period of 12.05 hours.
2001 AV43
is a member of the dynamical Apollo group, which are Earth-crossing asteroids. Apollo asteroids are the largest subgroup of near-Earth objects. Unlike many Apollo asteroids, this asteroid is not a Mars-crosser, as its aphelion is smaller than the orbit of the Red Planet at 1.66 AU.
Hygiea family
By far the largest member is 10 Hygiea, a 400 km diameter C-type asteroid that is the fourth largest in the belt. The remaining members are much smaller so Hygiea contains about 94–98% of the mass in the family (depending on the exact criteria for inclusion). The two next largest members are 333 Badenia, and 538 Friederike, both just over 70 km in diameter. After that, the remaining members have diameters of less than 30 km.
57424 Caelumnoctu
"Caelumnoctu" is a member the Eos family (), the largest asteroid family in the outer main belt consisting of nearly 10,000 asteroids.
2018 GE3
In observational history, and other than possibly 2002 MN and , this asteroid is the largest known object to ever pass that close to Earth, as well as the Moon "(also see History of closest approaches of large near-Earth objects)". 99942 Apophis will break both of these records when it approaches only from Earth on 13 April 2029.
(111253) 2001 XU10
, provisional designation , is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 3 kilometers in diameter. It was discovered on 9 December 2001, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. The asteroid is one of the largest potentially hazardous asteroids.
D-type asteroid
A list of some of the largest D-type asteroids.
511 Davida
Davida (minor planet designation: 511 Davida) is a large C-type asteroid in the asteroid belt. It was discovered by R. S. Dugan in 1903. It is one of the ten most-massive asteroids, and the 7th-largest asteroid. Davida is named after David Peck Todd, an astronomy professor at Amherst College.
6 Hebe
Hebe ( ; minor planet designation: 6 Hebe) is a large main-belt asteroid, containing around half a percent of the mass of the belt. However, due to its apparently high bulk density (greater than that of the Moon or even Mars), Hebe does not rank among the top twenty asteroids by volume. This high bulk density suggests an extremely solid body that has not been impacted by collisions, which is not typical of asteroids of its size – they tend to be loosely-bound rubble piles.
1299 Mertona
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, "Mertona" measures between 14.14 and 14.60 kilometers in diameter, and its surface has an albedo between 0.219 and 0.243. Although such a high albedo is typical for stony asteroids, the "Collaborative Asteroid Lightcurve Link" assumes an albedo of 0.057, which it uses as the generic albedo for all carbonaceous C-type asteroids. It therefore calculates a larger diameter of 27.90 kilometers (as the lower the albedo or reflectivity, the larger a body's diameter at an unchanged absolute magnitude or brightness). Carbonaceous asteroids are the predominant type in the outer main-belt, while stony asteroids are mostly found in the inner regions of the asteroid belt.
Extraterrestrial skies
The asteroid 87 Sylvia is one of the largest main-belt asteroids and the first asteroid observed to have two moons. These moons, Romulus and Remus, would appear roughly the same size. Romulus, the farther one, would be about 0.89° across, slightly bigger than the closer but smaller Remus, which would be about 0.78° across. Because Sylvia is far from spherical, these values can vary by about a little more than 10%, depending on where the observer is on Sylvia's surface. Since the two asteroidal moons appear to orbit (as best we can tell) in the same plane, they would occult each other once every 2.2 days. When the season is right, twice during Sylvia's 6.52 year orbital period, they would eclipse the Sun, which, at 0.15° across, is much smaller than when seen from Earth (0.53°). From Remus, the inner moon, Sylvia is huge, roughly 30°×18° across, while its view of Romulus varies between 1.59 and 0.50° across. From Romulus, Sylvia measures 16°×10° across, while Remus varies between 0.62° and 0.19°.
65 Cybele
Cybele ( minor planet designation: 65 Cybele) is one of the largest asteroids in the Solar System and is located in the outer asteroid belt. It gives its name to the Cybele group of asteroids that orbit outward from the Sun from the 2:1 orbital resonance with Jupiter. The X-type asteroid has a relatively short rotation period of 6.0814 hours. It was discovered by Wilhelm Tempel in 1861, and named after Cybele, the earth goddess.
Veneneia
Veneneia ( ) is the second-largest crater on asteroid 4 Vesta, at 52°S latitude. in diameter, it is 70% of the equatorial diameter of the asteroid, and one of the largest craters in the Solar System. It is at least 2 billion years old. However, it is overlain and partially obliterated by the even larger Rheasilvia. It was discovered by the "Dawn" spacecraft in 2011. It is named after "Venēneia", one of the founding vestal virgins.
Asteroid family
Additionally, some interlopers from the heterogeneous background asteroid population are expected even in the central regions of a family. Since the true family members caused by the collision are expected to have similar compositions, most such interlopers can in principle be recognised by spectral properties which do not match those of the bulk of family members. A prominent example is 1 Ceres, the largest asteroid, which is an interloper in the family once named after it (the Ceres family, now the Gefion family).
Chicxulub impactor
There are several competing models for the impactor's origin and its relationship to other asteroids that still exist in the Solar System. In September 2007, William F. Bottke, David Vokrouhlický, and David Nesvorný proposed an origin for the impactor in an article published in "Nature". This argued that a collision in the asteroid belt 160 million years ago resulted in the Baptistina family of asteroids, the largest surviving member of which is 298 Baptistina. They proposed that the Chicxulub impactor was an asteroid member of this group, referring to the large amount of carbonaceous material present in microscopic fragments at the site, suggesting that it was a member of a rare class of asteroids called carbonaceous chondrites, like Baptistina. According to Bottke, the Chicxulub impactor was a fragment of a much larger parent body about across, with the impacting body being around 60 km (40 mi) in diameter.
433 Eros
Eros ( ; minor planet designation: 433 Eros), provisional designation , is a stony and elongated asteroid of the Amor group and the first discovered and second-largest near-Earth object with a mean-diameter of approximately 16.8 kilometers. Visited by the NEAR Shoemaker space probe in 1998, it became the first asteroid ever studied from orbit.
31 Euphrosyne
It is a very little-studied body despite being one of the largest asteroids. It is a C-type asteroid with a primitive surface. Its orbit, however, is quite unusual and bears a considerable resemblance to that of 2 Pallas in its high inclination and eccentricity. Whereas Pallas and Eris—the only larger bodies with comparably tilted orbits—have nodes near perihelion and aphelion, Euphrosyne's perihelion lies at the northernmost point of its orbit. During a rare perihelic opposition Euphrosyne is very high in the sky from northern latitudes, but invisible from such countries as New Zealand and Chile.
(159857) 2004 LJ1
, provisional designation , is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 3 kilometers in diameter. The asteroid was discovered on 10 June 2004, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. It is one of the largest potentially hazardous asteroids known to exist.
Mario Jurić
Together with prolific amateur astronomer Korado Korlević, Jurić has co-discovered 125 asteroids, and one comet, 183P/Korlević-Jurić. He took part in discovery of the Sloan Great Wall, at the time the largest known structure in the Universe. His co-discovery, the Koronian asteroid 22899 Alconrad is one of the smallest known binary asteroids in the main-belt.
Asteroid impact avoidance
Nuclear standoff explosions are assessed to be 10–100 times more effective than the non-nuclear alternatives analyzed in this study. Other techniques involving the surface or subsurface use of nuclear explosives may be more efficient, but they run an increased risk of fracturing the target NEO. They also carry higher development and operations risks.
In the same year NASA released a study where the asteroid Apophis (with a diameter ~300 m) was assumed to have a much lower rubble pile density (1,500 kg/m) and therefore mass than is now known, and in the study, it is assumed to be on an impact trajectory with Earth for the year 2029. Under these hypothetical conditions, the report determines that a "Cradle spacecraft" would be sufficient to deflect it from Earth impact. This conceptual spacecraft contains six B83 physics packages, each set for their maximum 1.2 megatonne yield that are bundled together and lofted by an Ares V vehicle sometime in the 2020s, with each B83 being fuzed to detonate over the asteroid's surface at a height of 100 m ("1/3 of the objects diameter" as its stand-off), one after the other, with hour long intervals between each successive detonation. The results of this study indicated that a single employment of this "option can deflect NEOs of [100-500m diameter] two years before impact, and larger NEOs with at least five years warning". These effectiveness figures are considered to be "conservative" by its authors and only the thermal X-ray output of the B83 devices was considered, while neutron heating was neglected for ease of calculation purposes.
Near-Earth object
In 2000, NASA reduced its estimate of the number of existing near-Earth asteroids over one kilometer in diameter from 1,000–2,000 to 500–1,000. Shortly thereafter, the LINEAR survey provided an alternative estimate of . In 2011, on the basis of NEOWISE observations, the estimated number of one-kilometer NEAs was narrowed to (of which 93% had been discovered at the time), while the number of NEAs larger than 140 meters across was estimated at . The NEOWISE estimate differed from other estimates in assuming a slightly lower average asteroid albedo, which produces larger estimated diameters for the same asteroid brightness. This resulted in 911 then known asteroids at least 1 km across, as opposed to the 830 then listed by CNEOS. In 2017, using an improved statistical method, two studies reduced the estimated number of NEAs brighter than absolute magnitude 17.75 (approximately over one kilometer in diameter) to . The estimated number of asteroids brighter than absolute magnitude of 22.0 (approximately over 140 m across) rose to , double the WISE estimate, of which about a third are known as of 2018.
2002 JE9
The asteroid has an estimated diameter of about based on an absolute magnitude of 21.3. is considered significant due to having previously passed closer to the Earth; on 11 April 1971, it passed Earth at a distance of . is one of the largest objects known to have passed inside the orbit of the moon. During the close approach in 1971 the asteroid reached about apparent magnitude 10, about the same brightness as Saturn's moon Iapetus.
4 Vesta
Vesta is the second-most-massive and second-largest body in the asteroid belt, after the dwarf planet Ceres, and it contributes an estimated 9% of the mass of the asteroid belt.
It is slightly larger than Pallas, though significantly more massive. Vesta is the only known remaining rocky protoplanet (with a differentiated interior) of the kind that formed the terrestrial planets. Numerous fragments of Vesta were ejected by collisions one and two billion years ago that left two enormous craters occupying much of Vesta's southern hemisphere. Debris from these events has fallen to Earth as howardite–eucrite–diogenite (HED) meteorites, which have been a rich source of information about Vesta.
2018 CY2
is an Apollo asteroid. Apollo's cross the orbit of Earth and are the largest group of near-Earth objects with nearly 10 thousand known members. It orbits the Sun at a distance of 0.92–1.34 AU once every 14 months (438 days; semi-major axis of 1.13 AU). Its orbit has an eccentricity of 0.18 and an inclination of 27° with respect to the ecliptic. It is, however, not a Mars-crossing asteroid, as its aphelion of 1.34 AU is less than the orbit of the Red Planet at 1.666 AU. The body's observation arc begins its first observation at Mount Lemmon in February 2018.
C-type asteroid
C-type asteroids are extremely dark, with albedos typically in the 0.03 to 0.10 range. Consequently, whereas a number of S-type asteroids can normally be viewed with binoculars at opposition, even the largest C-type asteroids require a small telescope. The potentially brightest C-type asteroid is 324 Bamberga, but that object's very high eccentricity means it rarely reaches its maximum magnitude.
(89830) 2002 CE
(89830) 2002 CE, provisional designation , is a stony asteroid, classified as near-Earth object and potentially hazardous asteroid of the Amor group, approximately 3.1 kilometers in diameter. It was discovered on 1 February 2002, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. This asteroid is one of the largest potentially hazardous asteroid known to exist.
Asteroid belt
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Pluto's moon Charon (whose diameter is 1200 km).
Asteroid
Until the age of space travel, objects in the asteroid belt were merely pinpricks of light in even the largest telescopes and their shapes and terrain remained a mystery. The best modern ground-based telescopes and the Earth-orbiting Hubble Space Telescope can resolve a small amount of detail on the surfaces of the largest asteroids, but even these mostly remain little more than fuzzy blobs. Limited information about the shapes and compositions of asteroids can be inferred from their light curves (their variation in brightness as they rotate) and their spectral properties, and asteroid sizes can be estimated by timing the lengths of star occulations (when an asteroid passes directly in front of a star). Radar imaging can yield good information about asteroid shapes and orbital and rotational parameters, especially for near-Earth asteroids. In terms of delta-v and propellant requirements, NEOs are more easily accessible than the Moon.
V-type asteroid
V-type NEAS (or V-NEAs) are near-Earth asteroids with a V spectral type. Impacts of V-NEAs on the Earth, according to the known sample (data taken in 2016), occur once in about 12 million years and have the potential to cause disastrous effects on regional to global scale, producing craters as large as 30 km in diameter and releasing kinetic energy of as much as 3 Mt. This energy is almost 6 million times greater than the energy released during the Chelyabinsk event in 2013. Venus, Mars and the Moon will experience impacts with V-NEAs every 22 Myr, 125 Myr and 168 Myr, respectively. Two craters with confirmed basaltic impactor which fits with the impact rate found from V-type NEAs are the Strangways crater (24 km diameter) in Australia, the Nicholson crater (12.5 km diameter) in Canada. Some V-NEAs have orbits similar to that of the Bunburra Rockhole meteorite.
1467 Mashona
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, "Mashona" measures between 89.160 and 104.119 kilometers in diameter and its surface has an albedo between 0.05 and 0.083. The "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 107.54 kilometers based on an absolute magnitude of 8.57. Among nearly half a million asteroids, "Mashona" belongs to the 200 largest body's.
9549 Akplatonov
"Akplatonov" is a core member of the Eunomia family, a large group of stony S-type asteroids and the most prominent family in the intermediate main-belt. Alternatively, in Nesvorný's HCM-analysis, the asteroid belong's to the main belt's background population, while in an earlier such analysis, Thais Mothé-Diniz considered "Akplatonov" to be the largest body in a small cluster or clump of its own. It orbits the Sun in the central asteroid belt at a distance of 2.3–2.9 AU once every 4 years and 3 months (1,537 days; semi-major axis of 2.61 AU). Its orbit has an eccentricity of 0.11 and an inclination of 11° with respect to the ecliptic. The body's observation arc begins 4 years prior to its official discovery observation, with its first identification as at the discovering observatory in October 1981.
1588 Descamisada
"Descamisada" is a member of the Eos family (), the largest asteroid family in the outer main belt consisting of nearly 10,000 asteroids. It orbits the Sun in the outer main-belt at a distance of 2.8–3.2 AU once every 5 years and 3 months (1,924 days). Its orbit has an eccentricity of 0.07 and an inclination of 11° with respect to the ecliptic. "Descamisada"s observation arc begins with its official discovery observation, as no precoveries were taken and no prior identifications were made.
V-type asteroid
A V-type asteroid or Vestoid is an asteroid whose spectral type is that of 4 Vesta. Approximately 6% of main-belt asteroids are vestoids, with Vesta being by far the largest of them. They are relatively bright, and rather similar to the more common S-type asteroid, which are also made up of stony irons and ordinary chondrites, with V-types containing more pyroxene than S-types.
Jupiter trojan
The largest Jupiter trojan is 624 Hektor, which has an average diameter of 203 ± 3.6 km. There are few large Jupiter trojans in comparison to the overall population. With decreasing size, the number of Jupiter trojans grows very quickly down to 84 km, much more so than in the asteroid belt. A diameter of 84 km corresponds to an absolute magnitude of 9.5, assuming an albedo of 0.04. Within the 4.4–40 km range the Jupiter trojans' size distribution resembles that of the main-belt asteroids. Nothing is known about the masses of the smaller Jupiter trojans. The size distribution suggests that the smaller Trojans are the products of collisions by larger Jupiter trojans.
Asteroid
Asteroids vary greatly in size, from almost for the largest down to rocks just 1 meter across. The three largest are very much like miniature planets: they are roughly spherical, have at least partly differentiated interiors, and are thought to be surviving protoplanets. The vast majority, however, are much smaller and are irregularly shaped; they are thought to be either surviving planetesimals or fragments of larger bodies.
List of exceptional asteroids
Estimating the sizes of asteroids from observations is difficult due to their irregular shapes, varying albedo, and small angular diameter. For example, pure C-type asteroids are much darker than most. Asteroids with only one or two axes measured may have a falsely inflated geometric mean diameter if the unknown second or third axis is significantly smaller than the primary axis. Asteroid 16 Psyche has an IRAS diameter of 253 km, yet has a more recent and accurate geometric mean of only 186 km.
The number of bodies grows rapidly as the size decreases. Based on IRAS data there are about 140 main-belt asteroids with a diameter greater than 120 km. For a more complete list, see List of Solar System objects by size.
Asteroid
However, following the discovery of asteroids below ten meters in size, Rubin and Grossman's 2010 paper revised the previous definition of meteoroid to objects between 10 µm and 1 meter in size in order to maintain the distinction between asteroids and meteoroids. The smallest asteroids discovered (based on absolute magnitude "H") are with "H" = 33.2 and with "H" = 32.1 both with an estimated size of about 1 meter.
1148 Rarahu
"Rarahu" is a member the Eos family (), the largest asteroid family of the outer main belt, named after its parent body, the asteroid 221 Eos. The family consists of nearly 10,000 asteroids.
Near-Earth object
On March 23, 1989, the diameter Apollo asteroid 4581 Asclepius (1989 FC) missed the Earth by . If the asteroid had impacted it would have created the largest explosion in recorded history, equivalent to 20,000 megatons of TNT. It attracted widespread attention because it was discovered only after the closest approach.
Asteroid
In April 2018, the B612 Foundation reported "It's 100 percent certain we'll be hit [by a devastating asteroid], but we're not 100 percent sure when." Also in 2018, physicist Stephen Hawking,
in his final book "Brief Answers to the Big Questions", considered an asteroid collision to be the biggest threat to the planet. In June 2018, the US National Science and Technology Council warned that America is unprepared for an asteroid impact event, and has developed and released the ""National Near-Earth Object Preparedness Strategy Action Plan"" to better prepare. According to expert testimony in the United States Congress in 2013, NASA would require at least five years of preparation before a mission to intercept an asteroid could be launched.
Comet nucleus
The largest centaurs (unstable, planet crossing, icy asteroids) are estimated to be 250 km to 300 km in diameter. Three of the largest would include 10199 Chariklo (258 km), 2060 Chiron (230 km), and the currently lost 1995 SN55 (≈300 km).
Potentially hazardous object
With a mean-diameter of approximately 7 kilometers, the Apollo asteroid is likely the largest known potentially hazardous object, despite its fainter absolute magnitude of 15.2, compared to other listed objects in the table below "(note: calculated mean-diameters in table are inferred from the objects brightness and its (assumed) albedo. They are only an approximation.)". The lowest numbered PHA is 1566 Icarus.
Enstatite chondrite
The largest known E-type chondrite in the asteroid belt may be 21 Lutetia, with a diameter of approximately , based on observations from the "Rosetta" spacecraft, ESO's New Technology Telescope, NASA Infrared Telescope Facility, and the Spitzer Space Telescope.
B612 Foundation
The larger in size asteroids or other near-Earth objects (NEOs) are, the less frequently they impact the planet's atmosphere — large meteors seen in the skies are extremely rare, while medium-sized ones are less so, and much smaller ones are more commonplace. Although stony asteroids often explode high in the atmosphere, some objects, especially iron-nickel meteors and other types descending at a steep angle, can explode close to ground level or even directly impact onto land or sea. In the U.S. State of Arizona, the -wide Meteor Crater (officially named Barringer Crater) formed in a fraction of a second as nearly 160 million tonnes of limestone and bedrock were uplifted, creating its crater rim on formerly flat terrain. The asteroid that produced the Barringer Crater was only about 46 meters (150 ft.) in size; however it impacted the ground at a velocity of 12.8 kilometers per second (28,600 mph) and struck with an impact energy equivalent to a 10 megaton (TNT equivalent) nuclear bomb — about 625 times greater than the bomb that destroyed the city of Hiroshima during the Second World War. Tsunamis can also occur after a medium-sized or larger asteroid impacts an ocean surface or other large body of water.
Asteroid impact prediction
In April 2018, the B612 Foundation stated "It's 100 per cent certain we'll be hit [by a devastating asteroid], but we're not 100 per cent sure when." Also in 2018, physicist Stephen Hawking, in his final book "Brief Answers to the Big Questions", considered an asteroid collision to be the biggest threat to the planet. In June 2018, the US National Science and Technology Council warned that America is unprepared for an asteroid impact event, and has developed and released the ""National Near-Earth Object Preparedness Strategy Action Plan"" to better prepare.
24 Themis
Themis ('; minor planet designation: 24 Themis) is one of the largest asteroids in the asteroid belt. It is also the largest member of the Themis family. It was discovered by Annibale de Gasparis on 5 April 1853. It is named after Themis, the personification of natural law and divine order in Greek mythology.
Asteroids in fiction
Dwarf planet Ceres is the largest and first discovered planetoid of the main-belt asteroids.
Space colonization
Colonization of asteroids would require space habitats. The asteroid belt has significant overall material available, the largest object being Ceres, although it is thinly distributed as it covers a vast region of space. Unmanned supply craft should be practical with little technological advance, even crossing 500 million kilometers of space. The colonists would have a strong interest in assuring their asteroid did not hit Earth or any other body of significant mass, but would have extreme difficulty in moving an asteroid of any size. The orbits of the Earth and most asteroids are very distant from each other in terms of delta-v and the asteroidal bodies have enormous momentum. Rockets or mass drivers can perhaps be installed on asteroids to direct their path into a safe course.
(16960) 1998 QS52
, provisional designation , is a stony asteroid on a highly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. It was discovered on 25 August 1998, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. This asteroid is one of the largest potentially hazardous asteroid known to exist.
Global catastrophic risk
Several asteroids have collided with earth in recent geological history. The Chicxulub asteroid, for example, is theorized to have caused the extinction of the non-avian dinosaurs 66 million years ago at the end of the Cretaceous. No sufficiently large asteroid currently exists in an Earth-crossing orbit; however, a comet of sufficient size to cause human extinction could impact the Earth, though the annual probability may be less than 10. Geoscientist Brian Toon estimates that a 60-mile meteorite would be large enough to "incinerate everybody". Asteroids with around a 1 km diameter have impacted the Earth on average once every 500,000 years; these are probably too small to pose an extinction risk, but might kill billions of people. Larger asteroids are less common. Small near-Earth asteroids are regularly observed and can impact anywhere on the Earth injuring local populations. As of 2013, Spaceguard estimates it has identified 95% of all NEOs over 1 km in size.
2 Pallas
Pallas (minor-planet designation: 2 Pallas) is the second asteroid to have been discovered (after Ceres), and is one of the largest asteroids in the Solar System. With an estimated 7% of the mass of the asteroid belt, it is the third-most-massive asteroid, being 10–30% less massive than Vesta. It is in diameter, somewhat smaller than 4 Vesta. It is likely a remnant protoplanet.
Near-Earth object
Two of the biggest Near-Earth objects 433 Eros and 1036 Ganymed, were also some the earliest to be detected. 1036 Ganymed is about 20 miles in diameter. As bigger asteroids they reflected more light. One way around simply finding the NEOs that reflect the most visible light, is to use infrared telescopes that observe the objects heat emissions.
Asteroid impact prediction
The minimum orbit intersection distance (MOID) between an asteroid and the Earth is the distance between the closest points of their orbits. This first check is a coarse measure that does not allow an impact prediction to be made, but is based solely on the orbit parameters and gives an initial measure of how close to Earth the asteroid could come. If the MOID is large then the two objects never come near each other. In this case, unless the orbit of the asteroid is perturbed so that the MOID is reduced at some point in the future, it will never impact Earth and can be ignored. However if the MOID is small then it is necessary to carry out more detailed calculations to determine if an impact will happen in the future. NASA considers asteroids with a MOID of less than 0.05 AU and an absolute magnitude brighter than 22 to be a potentially hazardous asteroid.
Retrograde and prograde motion
Asteroids with satellites, also known as binary asteroids, make up about 15% of all asteroids less than 10 km in diameter in the main belt and near-Earth population and most are thought to be formed by the YORP effect causing an asteroid to spin so fast that it breaks up. As of 2012, and where the rotation is known, all satellites of asteroids orbit the asteroid in the same direction as the asteroid is rotating.
Hungaria asteroid
Most Hungarias are E-type asteroids, which means they have extremely bright enstatite surfaces and albedos typically above 0.30. Despite their high albedos, none can be seen with binoculars because they are far too small: the largest (434 Hungaria) is only about 11 km in size. They are, however, the smallest asteroids that can regularly be glimpsed with amateur telescopes.
4902 Thessandrus
The astronomers also detected a non-principal axis rotation seen in distinct rotational cycles in successive order. This is commonly known as tumbling. "Thessandrus" is the fourth-largest asteroid and largest Jupiter trojan known to be is such a state "(also see List of tumblers)."
Solar System
Asteroids except for the largest, Ceres, are classified as small Solar System bodies and are composed mainly of refractory rocky and metallic minerals, with some ice. They range from a few metres to hundreds of kilometres in size. Asteroids smaller than one meter are usually called meteoroids and micrometeoroids (grain-sized), depending on different, somewhat arbitrary definitions.
532 Herculina
Herculina is one of the larger members of the main asteroid belt. It is believed to rank among the top 20 in size, but the exact dimensions of many large asteroids are still uncertain. The current estimate for its mass would rank it close to the top 10.
(90075) 2002 VU94
, provisional designation , is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 2.5 kilometers in diameter. It was discovered on 13 November 2002, by astronomers of the Near-Earth Asteroid Tracking program at Palomar Observatory in California, United States. It is one of the largest potentially hazardous asteroid known to exist.
1036 Ganymed
1036 Ganymed (), provisional designation "", is a stony asteroid on a highly eccentric orbit, classified as a near-Earth object of the Amor group. It was discovered by German astronomer Walter Baade at the Bergedorf Observatory in Hamburg on 23 October 1924, and named after Ganymede from Greek mythology. With a diameter of approximately , "Ganymed" is the largest of all near-Earth objects. The S-type asteroid has a rotation period of 10.3 hours. In October 2024, it will approach Earth at .
163693 Atira
With a diameter of 4.8 kilometers, "Atira" is one of the largest Near-Earth objects. Early estimates of its size ranged from 1 to 2 kilometers, but those were based on an assumed higher albedo of 0.20. Its larger size and low albedo were discovered when "Atira" was imaged by radar in early 2017. These radar images also revealed that "Atira" is a binary asteroid.
176 Iduna
Iduna (minor planet designation: 176 Iduna) is a large main-belt asteroid that was discovered by German-American astronomer Christian Heinrich Friedrich Peters on October 14, 1877, in Clinton, New York. It is named after Sällskapet Idun, a club in Stockholm that hosted an astronomical conference; Idun is also a Norse goddess. A G-type asteroid, it has a composition similar to that of the largest main-belt asteroid, 1 Ceres.
10 Hygiea
Although it is the largest body in its region, due to its dark surface and farther-than-average distance from the Sun, Hygiea appears very dim when observed from Earth. In fact, it is the third dimmest of the first twenty-three asteroids discovered, with only 13 Egeria and 17 Thetis having lower mean opposition magnitudes. At most oppositions, Hygiea has a magnitude of around +10.2, which is as much as four orders fainter than Vesta, and observation calls for at least a telescope to resolve. However, at a perihelic opposition, Hygiea can reach +9.1 and may just be resolvable with 10x50 binoculars, unlike the next two largest asteroids in the asteroid belt, 704 Interamnia and 511 Davida, which are always beyond binocular visibility.
Near-Earth object
As of January 4, 2019 and mostly using the crude estimate from an absolute magnitude, 897 NEAs listed by CNEOS, including 156 PHAs, measure at least 1 km in diameter, and 8,452 known NEAs are larger than 140 m in diameter.
The smallest known near-Earth asteroid is with an absolute magnitude of 33.2, corresponding to a diameter of about . The largest such object is 1036 Ganymed, with an absolute magnitude of 9.45 and a diameter of about .
Karoo (crater)
The critical crater diameter is the scale at which cratering “goes global” and results in a solitary distinct crater. All smaller craters—however large D might be—are local events. Mathilde is thus a particularly interesting case, since it is the largest asteroid imaged at sufficient resolution to show that its topography is clearly exogenic, governed by impacts. Mathilde has several craters of a similar size to Karoo; according to gravity-regime scaling it suffered ∼5 impacts by objects, ranging from ∼0.8 to 1.2 km diameter, without being struck once by an object large enough to disrupt it. This seems odd, and Cheng and Barnouin-Jha (1999) find Mathilde’s survival unlikely, and appeal to oblique impacts. But it may be an effect of preservation in the case where D is so large that even hemisphere-spanning craters are, by definition, “local.” If, for example, Mathilde’s attenuation is somewhat higher than usual, say α = 1.4, then based on Fig. 2 none of its craters exceeds the critical crater diameter. This would explain the crowding of giant craters, since none of these would result in global degradation. Indeed, if Karoo, at 33 km diameter, represents D and resurfaced the asteroid, then the 5 or more other giant impacts must have happened subsequently, which is highly unusual given that they are in fact almost just as large. Thus α = 1.33 from Fig. 2a is likely a lower limit on Mathilde’s attenuation.
(285263) 1998 QE2
With a diameter between 2.7 and 3.2 kilometers, is one of largest known potentially hazardous asteroid "(see PHA-list)". Conversely, the "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.08 kilometers based on an absolute magnitude of 17.2.
Impact event
Stony asteroids with a diameter of enter Earth's atmosphere approximately once per year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much kinetic energy as the atomic bomb dropped on Hiroshima (approximately 16 kilotons of TNT), but the air burst is reduced to just 5 kilotons. These ordinarily explode in the upper atmosphere and most or all of the solids are vaporized. However, asteroids with a diameter of , and which strike Earth approximately twice every century, produce more powerful airbursts. The 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the one over Hiroshima. Much larger objects may impact the solid earth and create a crater.
2 Pallas
Both Vesta and Pallas have assumed the title of second-largest asteroid from time to time. At in diameter, Pallas is slightly smaller than Vesta (). The mass of Pallas is only 84% that of Vesta, 22% that of Ceres and about 0.3% that of the Moon.
2867 Šteins
On 11 May 2012, IAU's Working Group for Planetary System Nomenclature announced a naming system for geographical features on "Šteins". Inspired by the asteroid's gem-like shape, its crater are given the English-language names of precious stones, with the largest being named Diamond crater "(see below)".
List of asteroids in astrology
This asteroid is second largest in mass, fourth to be discovered of which it is the fastest to travel the zodiac and the last asteroid to be counted as a planet. In mythology Vesta the virgin goddess, the Roman version of Hestia, though she was of higher importance to the Romans, was regarded as one of the most important goddesses of all, though ironically she never was depicted in any visual art (in Greece, some vases with her image however have been found), or at least none of it has ever been found. She was the goddess of hearth, when a baby was born she was the goddess they would ask to bless it and protect the home. In every city and home in Rome there was a sacred fire made to Vesta that was protected and not allowed to go out. Astrologers use Vesta to determine what it is that you are devoted to and how your sexuality will develop. Vesta, having been a protective virgin goddess is said by some to be an influencer of the sign Virgo, this is accepted by many in the astrological community, but many prefer to instead of calling the influence an outright rulership an "affinity" or simply do not support this claim. It also seems to bear influence over Scorpio.
31 Euphrosyne
Euphrosyne (minor planet designation: 31 Euphrosyne) is the 12th-largest and the 5th-most-massive asteroid in the asteroid belt, discovered by James Ferguson on September 1, 1854. It was the first asteroid found from North America. It is named after Euphrosyne, one of the Charites in Greek mythology.