253 Mathilde, a C-type asteroid measuring about 50 km across. TemplateInfobox Planet. --> 253 Mathilde (məˈtɪldə is a main belt Asteroid that C-type asteroids are Carbonaceous Asteroids They are the most common variety forming around 75% of known Asteroids {Fact|date=July 2008}} and an even higher Photograph taken in 1997 by the NEAR Shoemaker probe. The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker renamed after its launch in honor of planetary scientist Eugene M

Asteroids, also called minor planets or planetoids, are Solar System bodies smaller than planets but larger than meteoroids (which are commonly defined as being 10 meters across or less),^[1] and that are not comets. Minor planet is a term used since the 19th century to describe objects such as Asteroids that are in Orbit around the Sun but are not Planets The Solar System consists of the Sun and those celestial objects bound to it by Gravity. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — The distinction between asteroids and comets is made on visual appearance when discovered: comets must show a perceptible coma (a fuzzy "atmosphere"), while asteroids do not. In Astronomy, a coma (from the Latin word for "hair" is the nebulous envelope around the nucleus of a Comet.

Asteroids vary greatly in size, from a few hundreds of kilometres in diameter down to rocks just tens of metres across. A few of the largest are roughly spherical and are very much like miniature planets. The vast majority, however, are much smaller and are irregularly shaped. The physical composition of asteroids is varied and in many cases poorly understood. Some are solid rocky bodies, with a greater or lesser metallic content, while others are piles of rubble held together loosely by gravity. Only one asteroid—Vesta—is visible to the naked eye, and this only in very dark skies when it is favourably positioned. TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt

The first named minor planet, Ceres, was discovered in 1801 by Giuseppe Piazzi, and was originally considered a new planet. Ceres (ˈsɪəriːz Giuseppe Piazzi ( July 7 1746 - July 22 1826) was an Italian Theatine monk Mathematician, and Astronomer ^[2] This was followed by the discovery of other similar bodies, which with the equipment of the time appeared to be points of light, like stars, showing little or no planetary disc (though readily distinguishable from stars due to their apparent motions). This prompted the astronomer Sir William Herschel to propose the term "asteroid", from Greek αστεροειδής, asteroeidēs = star-like, star-shaped, from ancient Greek Aστήρ, astēr = star. Sir Frederick William Herschel FRS KH ( 15 November 1738 – 25 August 1822) was a German -born British

The vast majority of known asteroids are found within the main asteroid belt, between the orbits of Mars and Jupiter, generally in relatively low-eccentricity (i. The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape e. , not very elongated) orbits. This belt is estimated to contain more than 750,000 asteroids larger than 1 kilometer across, and millions of smaller ones. ^[3] It is thought that these asteroids are remnants of the protoplanetary disk, and in this region the accretion of planetesimals into planets during the formative period of the solar system was prevented by large gravitational perturbations by Jupiter. A protoplanetary disk (or proplyd) is a rotating Circumstellar disk of dense gas surrounding a young newly formed star a T Tauri star or Herbig star In Astrophysics, the term accretion is used for at least two distinct processes Planetesimals are solid objects thought to exist in Protoplanetary disks and in Debris disks A widely accepted theory of planet formation the so-called planetesimal Some asteroids have moons or are found in co-orbiting pairs known as binary systems. An asteroid moon is an Asteroid that Orbits another asteroid as its Natural satellite. A binary asteroid is a system of two Asteroids orbiting their common Center of mass, in analogy with Binary stars The first such system to be discovered Minor planets have more recently been found to cross the orbits of planets, from Mercury to Neptune—with hundreds of trans-Neptunian objects (TNOs) now known to exist well past Neptune's orbit. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. (Using indirect methods, the total number of TNOs has been estimated in the hundreds of millions or even billions. )

Asteroids are given a provisional designation by year in the order of discovery, and a designation (a sequential number) and name if their existence is well established and an orbit has been determined. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star

Terminology

The term "asteroid" is used to describe any of a diverse group of small celestial bodies orbiting the Sun—traditionally in the inner Solar System, since those were the only ones known. In English it is the most commonly used word for a minor planet, which was the term preferred by the International Astronomical Union (IAU) prior to 2006. Minor planet is a term used since the 19th century to describe objects such as Asteroids that are in Orbit around the Sun but are not Planets Other languages prefer "planetoid" (Greek for "planet-like"). The word "planetesimal" has a similar meaning, but often refers specifically to small bodies that existed at the time the Solar System was forming. Planetesimals are solid objects thought to exist in Protoplanetary disks and in Debris disks A widely accepted theory of planet formation the so-called planetesimal The term "planetule" was coined by the geologist Conybeare to describe minor planets,^[4] but is not in common use.

Traditionally, small bodies orbiting the Sun were classified as asteroids, comets or meteoroids, with anything smaller than, say, ten metres across being called a meteoroid. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — The main difference between an asteroid and a comet is that a comet shows a coma due to sublimation of near surface ices by solar radiation. Outgassing (sometimes called offgassing, particularly when in reference to indoor Air quality is the slow release of a Gas that was trapped A few objects have ended up being dual-listed because they were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets eventually are depleted of their volatile ices and then appear as point-like objects, i. e. asteroids. A further distinction is that comets typically have more eccentric orbits than asteroids (though some objects classified as asteroids also have notably eccentric orbits).

In recent years, the situation has been complicated by the discovery of trans-Neptunian objects (TNOs). A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. These inhabit the cold outer reaches of the Solar System where ices remain solid and comet-like bodies are not expected to exhibit much cometary activity. The innermost of these are the Kuiper Belt Objects (KBOs), called "objects" partly to avoid the need to classify them as asteroids or comets. The Kuiper belt (ˈkaɪpɚ to rhyme with "viper" sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending ^[5] KBOs are believed to be predominantly comet-like in composition, though some may be more akin to asteroids. ^[6] Furthermore, they do not necessarily have the highly eccentric orbits usually associated with comets, and there are significant numbers very much larger than traditional comet nuclei. The nucleus is the solid central part of a Comet, popularly termed a dirty snowball. The much more distant Oort cloud is also hypothesised to be a reservoir of dormant comets. The Oort cloud ( ort alternatively the Öpik-Oort Cloud) is a hypothetical spherical cloud of Comets believed to lie roughly 50 000 AU,

Other recent observations, such as the analysis of the cometary dust collected by the Stardust probe, are increasingly blurring the distinction between comets and asteroids,^[7] suggesting "a continuum between asteroids and comets" rather than a sharp dividing line. Stardust is an American interplanetary mission of the NASA Jet Propulsion Laboratory, whose primary purpose was to investigate the makeup of the ^[8]

In late August 2006, the IAU introduced the class small solar system bodies (SSSB) to include most objects previously classified as minor planets and comets. Small Solar System Body ( SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — At the same time, the class dwarf planets was created for the largest minor planets—those which have sufficient mass to have become more-or-less spherical under their own gravity. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded According to the IAU, "the term 'minor planet' may still be used, but generally the term 'small solar system body' will be preferred. "^[9] Currently only the largest object in the asteroid belt, Ceres, at about 950 km across, is in the dwarf planet category, although there are several relatively large near-spherical asteroids (Vesta, Pallas and Hygiea) that may be reclassified as dwarf planets in future. Ceres (ˈsɪəriːz TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest ^[10]

Distribution within the Solar System

See also: Asteroid group, List of noteworthy asteroids, and List of asteroids

The Main asteroid belt (white) and the Trojan asteroids (green)

Hundreds of thousands of asteroids have been discovered within the Solar System, with the rate of discovery currently running at around 5,000 per month. The following is a collection of lists of notable asteroids in the Solar system, sometimes also including minor planets beyond the orbit of Jupiter. This is a list of numbered Minor planets in sequential order there are 192280 numbered minor planets and many more not yet numbered The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. Of the more than 400,000 registered minor planets, 187,745 have orbits known well enough to be assigned permanent official numbers. In ancient times only the Sun and Moon, a few hundred Stars and the most easily visible Planets had names ^[11][12] Of these, 14,525 have official names. ^[13] The lowest-numbered, unnamed minor planet is (3708) 1974 FV₁;^[14] the highest-numbered named minor planet is 181627 Philgeluck. ^[15] Current estimates put the total number of asteroids above 1 km in diameter in the Solar System to be between 1. 1 and 1. 9 million. ^[16] Ceres, with diameters of 975 × 909 km, was once considered the largest asteroid in the inner solar system, but it has since been recategorized as a dwarf planet. Ceres (ˈsɪəriːz A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded That distinction now falls to 2 Pallas and 4 Vesta; both have diameters of about 500 km. TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Normally Vesta is the only main belt asteroid that can, on occasion, become visible to the naked eye. However, on some very rare occasions, a near-Earth asteroid may briefly become visible without technical aid; see 99942 Apophis. TemplateInfobox Planet. --> 99942 Apophis (əˈpɒfɪs previously known by its provisional designation

Left to right: 4 Vesta, 1 Ceres, Earth's Moon

The mass of all the objects of the Main asteroid belt, lying between the orbits of Mars and Jupiter, is estimated to be about 3. TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Ceres (ˈsɪəriːz The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. 0-3. 6×10²¹ kg, or about 4 percent of the mass of the Moon. Of this, Ceres comprises 0. Ceres (ˈsɪəriːz 95×10²¹ kg, some 32 percent of the total. ^[17][18] Adding in the next three most massive asteroids, 4 Vesta (9%), 2 Pallas (7%), and 10 Hygiea (3%), brings this figure up to 51%; while the three after that, 511 Davida (1. TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet. --> 511 Davida (dəˈviːdə də-VEE-də is a large 2%), 704 Interamnia (1. TemplateInfobox Planet. --> 704 Interamnia (ˌɪntərˈæmniə in'-tər-am'-nee-ə from Latin 0%), and 52 Europa (0. TemplateInfobox Planet. --> 52 Europa (jʊˈroʊpə is an Asteroid. 9%), only add another 3% to the total mass. The number of asteroids then increases rapidly as their individual masses decrease.

Various classes of asteroid have been discovered outside the main asteroid belt. Near-Earth asteroids have orbits in the vicinity of Earth's orbit. Near-Earth asteroids (NEAs are Asteroids whose Orbits are close to Earth 's orbit Trojan asteroids are gravitationally locked into synchronisation with a planet, either leading or trailing the planet in its orbit. The majority of Trojans are associated with Jupiter, but a few have been found orbiting with Mars or Neptune. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. Asteroids orbiting between Jupiter and Neptune are called Centaurs, and beyond this lie swarms of trans-Neptunian objects. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. A group of asteroids called Vulcanoids are hypothesised by some to lie very close to the Sun, within the orbit of Mercury, but none has so far been found. Vulcanoids are a hypothetical group of Asteroids that may orbit in a dynamically stable zone between 0

Classification

Asteroids are commonly classified according to two criteria: the characteristics of their orbits, and features of their reflectance spectrum.

Orbit groups and families

Main articles: Asteroid group and Asteroid family

Many asteroids have been placed in groups and families based on their orbital characteristics. An asteroid family is a population of Asteroids that share similar Orbital elements, such as Semimajor axis, eccentricity, and orbital Inclination Apart from the broadest divisions, it is customary to name a group of asteroids after the first member of that group to be discovered. Groups are relatively loose dynamical associations, whereas families are much tighter and result from the catastrophic break-up of a large parent asteroid sometime in the past. ^[19] Families have only been recognized within the main asteroid belt. The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. They were first recognised by Kiyotsugu Hirayama in 1918 and are often called Hirayama families in his honor. was a Japanese Astronomer, best known for his discovery that many Asteroid orbits were more similar to one another than chance would allow leading to the concept A Hirayama family of Asteroids is a group of Minor planets that share similar Orbital elements, such as Semimajor axis, eccentricity

About 30% to 35% of the bodies in the main belt belong to dynamical families each thought to have a common origin in a past collision between asteroids. A family has also been associated with the Trans-Neptunian Object (136108) 2003 EL61.

Quasi-satellites and horseshoe objects

Some asteroids have unusual horseshoe orbits that are co-orbital with the Earth or some other planet. A horseshoe Orbit appears when a viewer on an orbiting body (like Earth watches the movement of another orbiting body whose orbit is skinnier (more eccentric but has about EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Examples are 3753 Cruithne and 2002 AA₂₉. TemplateInfobox Planet. --> 3753 Cruithne (ˈkrɪnjə from Old Irish ˈkrɪθnɛ Modern TemplateInfobox Planet. -->Asteroid ( also written 2002 AA29) is a Near-Earth asteroid The first instance of this type of orbital arrangement was discovered between Saturn's moons Epimetheus and Janus. TemplateInfobox Planet.--> Epimetheus (ˌɛpɨˈmiːθiəs,, or Saturn X redirects here For the spurious moon reported in 1905 see Themis (moon

Sometimes these horseshoe objects temporarily become quasi-satellites for a few decades or a few hundred years, before returning to their prior status. A quasi-satellite is an object in a 11 Orbital resonance with its Planet that stays close to the planet over many orbital periods Both Earth and Venus are known to have quasi-satellites. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University

Such objects, if associated with Earth or Venus or even hypothetically Mercury are a special class of Aten asteroids. The Aten asteroids are a group of Near-Earth asteroids named after the first of the group to be discovered ( 2062 Aten, discovered January 7 1976 by Eleanor F However, such objects could be associated with outer planets as well.

Spectral classification

This picture of 433 Eros shows the view looking from one end of the asteroid across the gouge on its underside and toward the opposite end. TemplateInfobox Planet. --> 433 Eros (ˈɪərɒs irr'-os) is the first discovered Near-Earth asteroid Features as small as 35 m across can be seen.

Main article: Asteroid spectral types

In 1975, an asteroid taxonomic system based on colour, albedo, and spectral shape was developed by Clark R. Asteroids are assigned a type based on spectral shape Color, and sometimes Albedo. Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos The albedo of an object is the extent to which it diffusely reflects light from the sun A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range compared Chapman, David Morrison, and Ben Zellner. Major General David Lindsay Morrison AM (b 1956 is the current Deputy Chief of the Australian Army. ^[20] These properties are thought to correspond to the composition of the asteroid's surface material. The original classification system had three categories: C-types for dark carbonaceous objects (75% of known asteroids), S-types for stony (silicaceous) objects (17% of known asteroids) and U for those that did not fit into either C or S. C-type asteroids are Carbonaceous Asteroids They are the most common variety forming around 75% of known Asteroids {Fact|date=July 2008}} and an even higher S-type asteroids are of a silicaceous ( stony) composition hence the name This classification has since been expanded to include a number of other asteroid types. The number of types continues to grow as more asteroids are studied.

The two most widely used taxonomies currently used are the Tholen classification and SMASS classification. The former was proposed in 1984 by David J. Tholen, and was based on data collected from an eight-color asteroid survey performed in the 1980s. Professional Life David James Tholen is an American Astronomer at the Institute for Astronomy of the University of Hawaii, who specializes This resulted in 14 asteroid categories. ^[21] In 2002, the Small Main-Belt Asteroid Spectroscopic Survey resulted in a modified version of the Tholen taxonomy with 24 different types. Both systems have three broad categories of C, S, and X asteroids, where X consists of mostly metallic asteroids, such as the M-type. M-type asteroids are Asteroids of unknown composition they are moderately bright ( Albedo 0 There are also a number of smaller classes. ^[22]

Note that the proportion of known asteroids falling into the various spectral types does not necessarily reflect the proportion of all asteroids that are of that type; some types are easier to detect than others, biasing the totals.

Problems with spectral classification

Originally, spectral designations were based on inferences of an asteroid's composition. ^[23] However, the correspondence between spectral class and composition is not always very good, and there are a variety of classifications in use. This has led to significant confusion. While asteroids of different spectral classifications are likely to be composed of different materials, there are no assurances that asteroids within the same taxonomic class are composed of similar materials.

At present, the spectral classification based on several coarse resolution spectroscopic surveys in the 1990s is still the standard. Scientists have been unable to agree on a better taxonomic system, largely due to the difficulty of obtaining detailed measurements consistently for a large sample of asteroids (e. g. finer resolution spectra, or non-spectral data such as densities would be very useful).

Discovery

243 Ida and its moon Dactyl, the first satellite of an asteroid to be discovered. TemplateInfobox Planet. --> 243 Ida (ˈaɪdə eye'-də) is a Main belt Asteroid

Historical methods

Asteroid discovery methods have dramatically improved over the past two centuries.

In the last years of the 18th century, Baron Franz Xaver von Zach organized a group of 24 astronomers to search the sky for the missing planet predicted at about 2. Baron Franz Xaver von Zach ( Franz Xaver Freiherr von Zach) ( June 4, 1754 &ndash September 2, 1832) was a Hungarian astronomer 8 AU from the Sun by the Titius-Bode law, partly as a consequence of the discovery, by Sir William Herschel in 1781, of the planet Uranus at the distance predicted by the law. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the The Sun (Sol is the Star at the center of the Solar System. The Titius–Bode law (sometimes termed just Bode's law) is a hypothesis that the bodies in some orbital systems including Sol 's orbit at semi-major axes Sir Frederick William Herschel FRS KH ( 15 November 1738 – 25 August 1822) was a German -born British This task required that hand-drawn sky charts be prepared for all stars in the zodiacal band down to an agreed-upon limit of faintness. Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic On subsequent nights, the sky would be charted again and any moving object would, hopefully, be spotted. The expected motion of the missing planet was about 30 seconds of arc per hour, readily discernible by observers.

Ironically, the first asteroid, 1 Ceres, was not discovered by a member of the group, but rather by accident in 1801 by Giuseppe Piazzi, director of the observatory of Palermo in Sicily. Ceres (ˈsɪəriːz Giuseppe Piazzi ( July 7 1746 - July 22 1826) was an Italian Theatine monk Mathematician, and Astronomer Palermo ( Sicilian: Palermu, Greek: Panormus, al-Madinah during Muslim rule is a historic City in Sicily ( Italian and Sicilian: Sicilia) is an autonomous region of Italy. He discovered a new star-like object in Taurus and followed the displacement of this object during several nights. Taurus (it looks like a bull (ˈtɔrəs bull, symbol, Unicode ♉ is one of the Constellations of the Zodiac. His colleague, Carl Friedrich Gauss, used these observations to determine the exact distance from this unknown object to the Earth. Johann Carl Friedrich Gauss (ˈɡaʊs, Gauß Carolus Fridericus Gauss ( 30 April 1777 – 23 February 1855) was a German Gauss' calculations placed the object between the planets Mars and Jupiter. Piazzi named it after Ceres, the Roman goddess of agriculture.

Three other asteroids (2 Pallas, 3 Juno, and 4 Vesta) were discovered over the next few years, with Vesta found in 1807. TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet. --> Juno (ˈdʒuːnoʊ or as Iūno designated 3 Juno in the Minor Planet TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt After eight more years of fruitless searches, most astronomers assumed that there were no more and abandoned any further searches.

However, Karl Ludwig Hencke persisted, and began searching for more asteroids in 1830. Fifteen years later, he found 5 Astraea, the first new asteroid in 38 years. TemplateInfobox Planet. --> 5 Astraea (əˈstriːə, Αστραία, written Astræa He also found 6 Hebe less than two years later. TemplateInfobox Planet. --> 6 Hebe (ˈhiːbi, ‘Ήβη) is a large Main belt After this, other astronomers joined in the search and at least one new asteroid was discovered every year after that (except the wartime year 1945). Notable asteroid hunters of this early era were J. R. Hind, Annibale de Gasparis, Robert Luther, H. M. S. Goldschmidt, Jean Chacornac, James Ferguson, Norman Robert Pogson, E. W. Tempel, J. C. Watson, C. H. F. Peters, A. Borrelly, J. Palisa, the Henry brothers and Auguste Charlois. Life and work John Russell Hind was born in 1823 in Nottingham. Annibale de Gasparis ( April 9 1819 – March 21 1892; anˈnibale de ˈgasparis was an Italian Astronomer. James Ferguson ( August 31 1797 – September 26 1867) was an American Astronomer and Engineer (he helped build the Honours The following celestial features are named after him Asteroid 1830 Pogson. Johann Palisa ( December 6 1848 – May 2 1925) was an Austrian Astronomer, born in Troppau in Austrian Paul-Pierre Henry ( Paul Henry) ( August 21 1848 &ndash January 4 1905) and his brother Mathieu-Prosper Henry ( Prosper Henry) (

In 1891, however, Max Wolf pioneered the use of astrophotography to detect asteroids, which appeared as short streaks on long-exposure photographic plates. Maximilian Franz Joseph Cornelius Wolf ( June 21 1863 – October 3 1932) was a German Astronomer, a pioneer of Astrophotography Astrophotography is a specialized type of Photography that entails making photographs of astronomical objects in the sky such as the Moon, Sun, Planets This dramatically increased the rate of detection compared with previous visual methods: Wolf alone discovered 248 asteroids, beginning with 323 Brucia, whereas only slightly more than 300 had been discovered up to that point. TemplateInfobox Planet. --> 323 Brucia (ˈbruːsiə brew'-see-ə or /ˈbruːʃə/ brew'-shə Still, a century later, only a few thousand asteroids were identified, numbered and named. It was known that there were many more, but most astronomers did not bother with them, calling them "vermin of the skies".

Manual methods of the 1900s and modern reporting

Until 1998, asteroids were discovered by a four-step process. First, a region of the sky was photographed by a wide-field telescope, or Astrograph. A photograph (often shortened to photo) is an Image created by Light falling on a light-sensitive surface usually Photographic film or an electronic A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. An Astrograph ( astrographic camera) is a telescope designed for the sole purpose of Astrophotography. Pairs of photographs were taken, typically one hour apart. Multiple pairs could be taken over a series of days. Second, the two films of the same region were viewed under a stereoscope. Stereoscopy, stereoscopic imaging or 3-D (three-dimensional imaging is any technique capable of recording three-dimensional visual Any body in orbit around the Sun would move slightly between the pair of films. Under the stereoscope, the image of the body would appear to float slightly above the background of stars. Third, once a moving body was identified, its location would be measured precisely using a digitizing microscope. The location would be measured relative to known star locations. ^[24]

These first three steps do not constitute asteroid discovery: the observer has only found an apparition, which gets a provisional designation, made up of the year of discovery, a letter representing the week of discovery, and finally a letter and a number indicating the discovery's sequential number (example: 1998 FJ₇₄). A provisional designation in astronomy is the naming convention applied to Astronomical objects immediately following their discovery

The final step of discovery is to send the locations and time of observations to the Minor Planet Center, where computer programs determine whether an apparition ties together previous apparitions into a single orbit. The Minor Planet Center operates at the Smithsonian Astrophysical Observatory (SAO which is part of the Center for Astrophysics (CfA along with the Harvard If so, the object receives a catalogue number and the observer of the first apparition with a calculated orbit is declared the discoverer, and granted the honor of naming the object subject to the approval of the International Astronomical Union.

Computerized methods

2004 FH is the center dot being followed by the sequence; the object that flashes by during the clip is an artificial satellite. TemplateInfobox Planet. --> 2004 FH is a Near-Earth asteroid that was discovered on March This article is about artificial satellites For natural satellites also known as moons see Natural satellite.

There is increasing interest in identifying asteroids whose orbits cross Earth's, and that could, given enough time, collide with Earth (see Earth-crosser asteroids). EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The three most important groups of near-Earth asteroids are the Apollos, Amors, and Atens. Near-Earth asteroids (NEAs are Asteroids whose Orbits are close to Earth 's orbit The Amor asteroids are a group of Near-Earth asteroids named after the asteroid 1221 Amor. The Aten asteroids are a group of Near-Earth asteroids named after the first of the group to be discovered ( 2062 Aten, discovered January 7 1976 by Eleanor F Various asteroid deflection strategies have been proposed, as early as the 1960s. Asteroid deflection strategies are methods by which Near-Earth objects could be diverted preventing potentially catastrophic Impact events A sufficiently large

The near-Earth asteroid 433 Eros had been discovered as long ago as 1898, and the 1930s brought a flurry of similar objects. Near-Earth objects ( NEOs) are Asteroids Comets and large Meteoroids whose orbits bring them close ( Perihelion distance AU TemplateInfobox Planet. --> 433 Eros (ˈɪərɒs irr'-os) is the first discovered Near-Earth asteroid In order of discovery, these were: 1221 Amor, 1862 Apollo, 2101 Adonis, and finally 69230 Hermes, which approached within 0. TemplateInfobox Planet. --> 1862 Apollo ( is a Q-type asteroid, discovered by Karl Reinmuth TemplateInfobox Planet. --> 2101 Adonis was one of the first Near-Earth asteroids to be discovered TemplateInfobox Planet. --> 69230 Hermes is an Apollo, Mars- and Venus-crosser asteroid 005 AU of the Earth in 1937. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Astronomers began to realize the possibilities of Earth impact.

Two events in later decades increased the level of alarm: the increasing acceptance of Walter Alvarez' hypothesis that an impact event resulted in the Cretaceous-Tertiary extinction, and the 1994 observation of Comet Shoemaker-Levy 9 crashing into Jupiter. For his grandfather the American doctor see Walter C Alvarez. See also Impact crater An impact event is the Collision of a large Meteoroid, Asteroid or Comet (generically The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets. The U. S. military also declassified the information that its military satellites, built to detect nuclear explosions, had detected hundreds of upper-atmosphere impacts by objects ranging from one to 10 metres across.

All of these considerations helped spur the launch of highly efficient automated systems that consist of Charge-Coupled Device (CCD) cameras and computers directly connected to telescopes. A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors Since 1998, a large majority of the asteroids have been discovered by such automated systems. A list of teams using such automated systems includes:^[25]

• The Lincoln Near-Earth Asteroid Research (LINEAR) team
• The Near-Earth Asteroid Tracking (NEAT) team
• Spacewatch
• The Lowell Observatory Near-Earth-Object Search (LONEOS) team
• The Catalina Sky Survey (CSS)
• The Campo Imperatore Near-Earth Objects Survey (CINEOS) team
• The Japanese Spaceguard Association
• The Asiago-DLR Asteroid Survey (ADAS)

The LINEAR system alone has discovered 84,764 asteroids, as of August 28, 2007. The LI ncoln N ear- E arth A steroid R esearch ( LINEAR) project is a cooperative project between the United States Air Force Near Earth Asteroid Tracking (NEAT is a program run by NASA and Jet Propulsion Laboratory to discover Near-Earth objects The NEAT system began observations Spacewatch is a project at the University of Arizona that specializes in the study of Minor planets including various types of Asteroids and Comets Lowell Observatory Near-Earth-Object Search (LONEOS was a project designed to discover Asteroids and Comets that orbit near the Earth Catalina Sky Survey is a project to discover Comets and Asteroids and to search for Near-Earth objects More specifically to search for Potentially The is a Not-for-profit organization based in Tokyo, Japan. Its aim echoes that of The Spaceguard Foundation and other Spaceguard movements Events 475 - The Roman General Orestes forces western Roman Emperor Julius Nepos to flee his Capital Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. ^[26] Between all of the automated systems, 4711 near-Earth asteroids have been discovered^[27] including over 600 more than 1 km in diameter.

Naming

Overview: naming conventions

A newly discovered asteroid is given a provisional designation (such as 2002 AT₄) consisting of the year of discovery and an alphanumeric code indicating the half-month of discovery and the sequence within that half-month. A provisional designation in astronomy is the naming convention applied to Astronomical objects immediately following their discovery (also written 2002 AT4) is an as yet unnamed and un-numbered Near-Earth asteroid. Once an asteroid's orbit has been confirmed, it is given a number, and later may also be given a name (e. g. 433 Eros). TemplateInfobox Planet. --> 433 Eros (ˈɪərɒs irr'-os) is the first discovered Near-Earth asteroid The formal naming convention uses parentheses around the number (e. g. (433) Eros), but dropping the parentheses is quite common. Informally, it is common to drop the number altogether, or to drop it after the first mention when a name is repeated in running text.

Asteroids that have been given a number but not a name keep their provisional designation, e. g. (29075) 1950 DA. As modern discovery techniques are finding vast numbers of new asteroids, they are increasingly being left unnamed. The first asteroid to be left unnamed was for a long time (3360) 1981 VA, now 3360 Syrinx; as of November 2006, this distinction is now held by (3708) 1974 FV₁. (3360 Syrinx (originally designated 1981 VA) is an Apollo and Mars crosser Asteroid discovered in 1981 (3708 1974 FV1 is a Trojan asteroid, approximately 80 kilometers in diameter On rare occasions, a small body's provisional designation may become used as a name in itself: the still unnamed (15760) 1992 QB₁ gave its name to a group of Kuiper belt objects which became known as cubewanos. A provisional designation in astronomy is the naming convention applied to Astronomical objects immediately following their discovery The Kuiper belt (ˈkaɪpɚ to rhyme with "viper" sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending In astronomy a classical Kuiper Belt object, also called a cubewano (ˌkjuːbiːˈwɑːnoʊ is a Kuiper belt object that Orbits beyond Neptune

Numbering

Asteroids are awarded with an official number once their orbits are confirmed. With the increasing rapidity of asteroid discovery, asteroids are currently being awarded six-figure numbers. The switch from five figures to six figures arrived with the publication of the Minor Planet Circular (MPC) of October 19, 2005, which saw the highest numbered asteroid jump from 99947 to 118161. The Minor Planet Circulars (MPCs (also known as Minor Planets and Comets are published generally on the date of each full moon by the Minor Planet Center. Events 202 BCE - The Battle of Zama results in the defeat of Carthage and Hannibal. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. This change caused a small Y2K-like crisis for various automated data services, since only five digits were allowed in most data formats for the asteroid number. The Year 2000 problem (also known as the Y2K problem, the millennium bug, the Y2K bug, or simply Y2K) was a notable Computer bug resulting Most services have now widened the asteroid number field. For those which did not, the problem has been addressed in some cases by having the leftmost digit (the ten-thousands place) use the alphabet as a digit extension. A=10, B=11,. . . , Z=35, a=36,. . . , z=61. A high number such as 120437 is thus cross-referenced as C0437 on some lists.

Sources for names

Main article: Meanings of asteroid names

The first few asteroids were named after figures from Graeco-Roman mythology, but as such names started to dwindle the names of famous people, literary characters, discoverer's wives, children, and even television characters were used. This is a list of named Minor planets (mostly Asteroids, with links to the Wikipedia articles on the people places characters and concepts that they are named after

The first asteroid to be given a non-mythological name was 20 Massalia, named after the city of Marseilles. TemplateInfobox Planet. --> 20 Massalia (məˈseɪliə Μασσαλία) is a large and fairly Marseille, ( English alt Marseilles mɑrˈseɪ — French: maʁsɛj locally — Provençal Occitan: Marselha maʀˈsijɔ For some time only female (or feminized) names were used; Alexander von Humboldt was the first man to have an asteroid named after him, but his name was feminized to 54 Alexandra. (September 14 1769 &ndash May 6 1859 was a German naturalist and explorer, and the younger brother of the Prussian minister philosopher and linguist TemplateInfobox Planet. --> 54 Alexandra is a very large and dark Main belt Asteroid. This unspoken tradition lasted until 334 Chicago was named; even then, oddly feminised names show up in the list for years afterward. 334 Chicago is a very large Main belt Asteroid. It is classified as a C-type asteroid and is probably composed of Carbonaceous material

As the number of asteroids began to run into the hundreds, and eventually the thousands, discoverers began to give them increasingly frivolous names. The first hints of this were 482 Petrina and 483 Seppina, named after the discoverer's pet dogs. 482 Petrina Aspects 483 Seppina However, there was little controversy about this until 1971, upon the naming of 2309 Mr. Spock (the name of the discoverer's cat). This article is about the asteroid For other uses see Spock (disambiguation. Although the IAU subsequently banned pet names as sources, eccentric asteroid names are still being proposed and accepted, such as 4321 Zero, 6042 Cheshirecat, 9007 James Bond, 13579 Allodd, 24680 Alleven, or 26858 Misterrogers. 4321 Zero (1981 EH26 is a Main-belt Asteroid discovered on March 2, 1981 by S 6042 Cheshirecat (1990 WW2 is a Mars-crossing Asteroid discovered on November 23, 1990 by A Asteroid 9007 James Bond ( was discovered on 5 October 1983 by Antonín Mrkos at the Kleť Observatory in the Czech Republic 24680 Alleven (1989 YE4 is a Main-belt Asteroid discovered on December 30, 1989 by R TemplateInfobox Planet. --> 26858 Misterrogers ( is a Main Belt Asteroid named after beloved

Special naming rules

Asteroid naming is not always a free-for-all: there are some types of asteroid for which rules have developed about the sources of names. For instance Centaurs (asteroids orbiting between Saturn and Neptune) are all named after mythological centaurs, Trojans after heroes from the Trojan War, and trans-Neptunian objects after underworld spirits. In Greek mythology, the centaurs (from Ancient Greek: Κένταυροι - Kéntauroi are a race of creatures composed of part Human In Greek mythology, the Trojan War was waged against the city of Troy by the Achaeans after Paris of Troy stole Helen from her A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune.

Another well-established rule is that comets are named after their discoverer(s), whereas asteroids are not. One way to circumvent this rule has been for astronomers to exchange the courtesy of naming their discoveries after each other. A particular exception to this rule is 96747 Crespodasilva, which was named after its discoverer, Lucy d'Escoffier Crespo da Silva, because she died shortly after the discovery, at age 22. 96747 Crespodasilva is a main-belt asteroid discovered by Lucy D’Escoffier Crespo da Silva. Lucy d'Escoffier Crespo da Silva (1978 – November 19 2000 was a senior at Massachusetts Institute of Technology and a promising astronomer for whom the asteroid 96747 ^[28][29] A few objects are also cross-listed as both comets and asteroids, such as 4015 Wilson-Harrington and 107P/Wilson-Harrington.

Symbols

The first few asteroids discovered were assigned symbols like the ones traditionally used to designate Earth, the Moon, the Sun and planets. The symbols quickly became ungainly, hard to draw and recognise. By the end of 1851 there were 15 known asteroids, each (except one) with its own symbol(s). ^[30]

Asteroid	Symbol
Ceres
2 Pallas
3 Juno
4 Vesta
5 Astraea
6 Hebe
7 Iris
8 Flora
9 Metis
10 Hygiea
11 Parthenope
12 Victoria
13 Egeria	Never assigned. Ceres (ˈsɪəriːz TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet. --> Juno (ˈdʒuːnoʊ or as Iūno designated 3 Juno in the Minor Planet TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt TemplateInfobox Planet. --> 5 Astraea (əˈstriːə, Αστραία, written Astræa TemplateInfobox Planet. --> 6 Hebe (ˈhiːbi, ‘Ήβη) is a large Main belt TemplateInfobox Planet. --> 7 Iris (ˈaɪrɪs Ίρις) is a large Main belt TemplateInfobox Planet. --> 8 Flora (ˈflɔərə Flōra is a large bright Main belt Asteroid For the moon of Jupiter, see Metis (moon. TemplateInfobox Planet.
14 Irene	"A dove carrying an olive-branch, with a star on its head," never drawn. [31]
15 Eunomia
28 Bellona
35 Leukothea
37 Fides

Johann Franz Encke made a major change in the Berliner Astronomisches Jahrbuch (BAJ, Berlin Astronomical Yearbook) for 1854. TemplateInfobox Planet. --> 28 Bellona (, Bellōna is a large Main belt Asteroid. TemplateInfobox Planet. --> 35 Leukothea () is a large dark Main belt Asteroid. TemplateInfobox Planet. --> 37 Fides (ˈfaɪdiz) is a large Main belt Asteroid. Johann Franz Encke ( 23 September 1791 – 26 August 1865) was a German Astronomer, born in Hamburg. He introduced encircled numbers instead of symbols, although his numbering began with Astraea, the first four asteroids continuing to be denoted by their traditional symbols. TemplateInfobox Planet. --> 5 Astraea (əˈstriːə, Αστραία, written Astræa This symbolic innovation was adopted very quickly by the astronomical community. The following year (1855), Astraea's number was bumped up to 5, but Ceres through Vesta would be listed by their numbers only in the 1867 edition. A few more asteroids (28 Bellona,^[32] 35 Leukothea,^[33] and 37 Fides^[34]) would be given symbols as well as using the numbering scheme. TemplateInfobox Planet. --> 28 Bellona (, Bellōna is a large Main belt Asteroid. TemplateInfobox Planet. --> 35 Leukothea () is a large dark Main belt Asteroid. TemplateInfobox Planet. --> 37 Fides (ˈfaɪdiz) is a large Main belt Asteroid. The circle would become a pair of parentheses, and the parentheses sometimes omitted altogether over the next few decades. ^[31]

Exploration

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. Spaceflight is the use of Space technology to fly a Spacecraft into and through Outer space. The best modern ground-based telescopes, as well as the Earth-orbiting Hubble Space Telescope, can resolve a small amount of detail on the surfaces of the very largest asteroids, but even these mostly remain little more than fuzzy blobs. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into 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). In Astronomy, a light curve is a graph of light intensity of a Celestial object or region as a function of time Radar imaging can yield good information about asteroid shapes and orbital and rotational parameters, especially for near-Earth asteroids. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships

The first close-up photographs of asteroid-like objects were taken in 1971 when the Mariner 9 probe imaged Phobos and Deimos, the two small moons of Mars, which are probably captured asteroids. In Film, Television, and Still photography a close-up tightly frames a person or an object Mariner 9 (Mariner Mars '71 / Mariner-I was a NASA space probe orbiter that helped in the exploration of Mars and was part of the Mariner program. TemplateInfobox Planet.--> Deimos (ˈdaɪməs; also /ˈdiːməs/ These images revealed the irregular, potato-like shapes of most asteroids, as did subsequent images from the Voyager probes of the small moons of the gas giants. See also Voyager 1 and Voyager 2. The Voyager program consists of a pair of unmanned scientific probes Voyager 1 and A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily

951 Gaspra, the first asteroid to be imaged in close up. TemplateInfobox Planet. --> 951 Gaspra (ˈɡæsprə is an S-type Asteroid that orbits very

The first true asteroid to be photographed in close-up was 951 Gaspra in 1991, followed in 1993 by 243 Ida and its moon Dactyl, all of which were imaged by the Galileo probe en route to Jupiter. TemplateInfobox Planet. --> 951 Gaspra (ˈɡæsprə is an S-type Asteroid that orbits very TemplateInfobox Planet. --> 243 Ida (ˈaɪdə eye'-də) is a Main belt Asteroid (243 Ida I Dactyl (ˈdæktɨl dak'-tl) is a tiny Asteroid moon (diameter 1 Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer

The first dedicated asteroid probe was NEAR Shoemaker, which photographed 253 Mathilde in 1997, before entering into orbit around 433 Eros, finally landing on its surface in 2001. The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker renamed after its launch in honor of planetary scientist Eugene M TemplateInfobox Planet. --> 253 Mathilde (məˈtɪldə is a main belt Asteroid that TemplateInfobox Planet. --> 433 Eros (ˈɪərɒs irr'-os) is the first discovered Near-Earth asteroid

Other asteroids briefly visited by spacecraft en route to other destinations include 9969 Braille (by Deep Space 1 in 1999), and 5535 Annefrank (by Stardust in 2002). 9969 Braille is a small Mars crossing asteroid that orbits the Sun once every 3 Deep Space 1 is a Spacecraft launched on 24 October 1998 as part of NASA 's New Millennium program. 5535 Annefrank ( is an inner main belt Asteroid, and member of the Augusta family. Stardust is an American interplanetary mission of the NASA Jet Propulsion Laboratory, whose primary purpose was to investigate the makeup of the

In September 2005, the Japanese Hayabusa probe started studying 25143 Itokawa in detail and may return samples of its surface to earth. is an Unmanned space mission led by the Japan Aerospace Exploration Agency to return a sample of material from a small Near-Earth asteroid named TemplateInfobox Planet. --> 25143 Itokawa (ˌiːtoʊˈkɑːwə Japanese イトカワ from 糸川 The Hayabusa mission has been plagued with difficulties, including the failure of two of its three control wheels, rendering it difficult to maintain its orientation to the sun to collect solar energy. Following that, the next asteroid encounters will involve the European Rosetta probe (launched in 2004), which will study 2867 Šteins and 21 Lutetia in 2008 and 2010. Rosetta is a European Space Agency -led Robotic spacecraft mission launched in 2004 intended to study the comet 67P/Churyumov-Gerasimenko. TemplateInfobox Planet. --> 21 Lutetia (ljuˈtiːʃiə Lutētia is a large Main belt Asteroid

In September 2007, NASA launched the Dawn Mission, which will orbit the dwarf planet Ceres and the asteroid 4 Vesta in 2011-2015, with its mission possibly then extended to 2 Pallas. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program Dawn, launched on September 27 2007 is a Robotic spacecraft being sent by NASA on a Space exploration mission to the two most massive members Ceres (ˈsɪəriːz TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest

It has been suggested that asteroids might be used in the future as a source of materials which may be rare or exhausted on earth (asteroid mining), or materials for constructing space habitats (see Colonization of the asteroids). Raw resources and minerals could be mined from an Asteroid in space using a variety of methods A space habitat, also called space colony, orbital colony, space city, or space settlement is a Space station intended as a The Asteroids or more properly the Minor planets, have long been suggested as possible sites for human colonization Materials that are heavy and expensive to launch from earth may someday be mined from asteroids and used for space manufacturing and construction. Space manufacturing is the production of Manufactured goods in an environment outside a Planetary atmosphere.

In fiction

Main article: Asteroids in fiction

Asteroids and asteroid belts are a staple of science fiction stories. Asteroids and Asteroid belts are a staple of Science fiction stories'. Asteroids play several potential roles in science fiction: as places which human beings might colonize; as resources for extracting minerals; as a hazard encountered by spaceships travelling between two other points; and as a threat to life on Earth due to potential impacts.

See also

References

External links

• Alphabetical list of minor planet names (ASCII) (Minor Planet Center)
• Near Earth Asteroid Tracking (NEAT)
• Asteroids Page at NASA's Solar System Exploration
• Asteroid Simulator with Moon and Earth
• Everything you wanted to know about comets and asteroids - Provided by New Scientist. New Scientist is a weekly International science magazine and website covering recent developments in science and technology for a general English -speaking
• Alphabetical and numerical lists of minor planet names (Unicode) (Institute of Applied Astronomy)
• Known Asteroid Impacts & Their Effects
• Assyrian clay tablet points to 'Sodom and Gomorrah' asteroid
• Future Asteroid Interception Research
• Near Earth Objects Dynamic Site
• Asteroids Dynamic Site Up-to date osculating orbital elements and proper orbital elements
• Asteroid naming statistics
• Spaceguard UK
• Large amount of information on asteroid groups collected by Gérard Faure, translation Richard Miles. In Astronomy, and in particular in Astrodynamics, the osculating orbit of an object in space is the gravitational Kepler orbit about a central body that The elements of an orbit are the parameters needed to specify that Orbit uniquely given a model of two point-masses obeying the Newtonian laws of motion and the The proper orbital elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale
• Near Earth Objects and Asteroids: Are We Whistling in the Dark?
• 1908 Siberian asteroid
• Committee on Small Body Nomenclature
• List of minor planet orbital groupings and families from ProjectPluto
• Cunningham, Clifford, "Introduction to Asteroids: The Next Frontier", ISBN 0-943396-16-6
• James L. Hilton: When Did the Asteroids Become Minor Planets?
• Kirkwood, Daniel; Relations between the Motions of some of the Minor Planets (1874).
• Schmadel, L. James Lindsay Hilton (born February 21, 1957) has been an astronomer at the United States Naval Observatory since 1986. D. (2003). Dictionary of Minor Planet Names. 5th ed. IAU/Springer-Verlag: Heidelberg.
• Large amount of information on asteroid groups collected by Gérard Faure, translation Richard Miles.