What is the largest asteroid?
5595163#17
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.
Ceres (dwarf planet)
791#37
The dwarf planet Ceres is by far the largest asteroid, with a diameter of . The next largest are 4 Vesta and 2 Pallas, both with diameters of just over . Vesta is the only main-belt asteroid that can, on occasion, be visible to the naked eye. On some rare occasions, a near-Earth asteroid may briefly become visible without technical aid; see 99942 Apophis.
Asteroid
791#40
Although their location in the asteroid belt excludes them from planet status, the three largest objects, Ceres, Vesta, and Pallas, are intact protoplanets that share many characteristics common to planets, and are atypical compared to the majority of "potato"-shaped asteroids. The fourth largest asteroid, Hygiea, has an undifferentiated interior, like the majority of asteroids. Between them, the four largest asteroids constitute half the mass of the asteroid belt.
Asteroid
532253#4
The largest unequivocally C-type asteroid is 10 Hygiea, although the SMASS classification places the largest asteroid, 1 Ceres, here as well, because that scheme lacks a G-type.
C-type asteroid
4511790#11
After Ceres, Asteroid 433 Eros is perhaps the most-commonly mentioned asteroid, probably because it is one of the largest near-Earth asteroids.
Asteroids in fiction
725656#0
Eunomia (minor planet designation 15 Eunomia) is a very large asteroid in the inner asteroid belt. It is the largest of the stony (S-type) asteroids, and somewhere between the 8th- and 12th-largest main-belt asteroid overall (uncertainty in diameters causes uncertainty in its ranking). It is the largest Eunomian asteroid, and is estimated to contain 1% of the mass of the asteroid belt.
15 Eunomia
791#46
The physical composition of asteroids is varied and in most cases poorly understood. Ceres appears to be composed of a rocky core covered by an icy mantle, where Vesta is thought to have a nickel-iron core, olivine mantle, and basaltic crust. 10 Hygiea, however, which appears to have a uniformly primitive composition of carbonaceous chondrite, is thought to be the largest undifferentiated asteroid. Most of the smaller asteroids are thought to be piles of rubble held together loosely by gravity, though the largest are probably solid. Some asteroids have moons or are co-orbiting binaries: Rubble piles, moons, binaries, and scattered asteroid families are thought to be the results of collisions that disrupted a parent asteroid, or, possibly, a planet.
Asteroid
735072#3
Angelina is an uncommon form of E-type asteroid; it is the third largest E-type after 44 Nysa and 55 Pandora, and has an exceptionally high albedo. As of 1991, it is thought to have an average radius of about . Back when asteroids were generally assumed to have low albedos, Angelina was thought to be the largest of this class, but modern research has shown that its diameter is only a quarter of what was previously assumed, an error caused by its exceptional brightness. Traditional calculations had suggested that since Angelina has an absolute magnitude of 7.7 and an albedo of 0.15, its diameter would have been around 100 km. However, a 2004 occultation showed a cross-sectional profile of only 48x53 km. Angelina was observed by Arecibo radar in January 2010.
64 Angelina
16476264#0
1512 Oulu, provisional designation , is a dark Hildian asteroid, slow rotator and possibly the largest known tumbler orbiting in the outermost region of the asteroid belt. With a diameter of approximately 80 kilometers, it belongs to the fifty largest asteroids in the outer main-belt. The body was discovered on 18 March 1939, by Finnish astronomer Heikki Alikoski at Turku Observatory in Southwest Finland and named for the Finnish town Oulu.
1512 Oulu
4511790#14
Asteroid 2 Pallas is the third-largest belt asteroid.Asteroid 4 Vesta is the second largest of the asteroids.A common depiction of asteroids (and less often, of comets) in fiction is as a threat, whose impact on Earth could result with incalculable damage and loss of life. This scenario is based on such past events as the impact event responsible for the extinction of the dinosaurs. Such events are, however, sufficiently rare that there is no special reason to expect such an impact in the near future.When the theme of interplanetary colonization first entered SF, the Asteroid Belt was quite low on the list of desirable real estate, far behind such planets as Mars and Venus (often conceived as a kind of paradise planet, until probes in the 1960s revealed uninhabitable temperatures with a deadly carbon dioxide and sulfur atmosphere under its clouds). Thus, in many stories and books the Asteroid Belt, if not a positive hazard, is still a rarely visited backwater in a colonized Solar System.Before colonization of the asteroids became an attractive possibility, a main interest in them was theories as to their origin – specifically, the theory that the asteroids are remnants of an exploded planet. This naturally leads to SF plot lines dealing with the possibility that the planet had been inhabited, and if so – that the inhabitants caused its destruction themselves, by war or gross environmental mismanagement. A further extension is from the past of the existing asteroids to the possible future destruction of Earth or other planets and their rendering into new asteroids.
Asteroids in fiction