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List Of Fast Rotators (minor Planets)
This is a list of fast rotators—"minor planets" (which includes asteroids) that have an exceptionally short rotation period, i.e. high rotation rate or spin rate. In some cases the rotation period is not constant because the object tumbles (see List of tumblers). In this list the periods are sourced from the ''Light Curve Data Base'' (LCDB), and are given in both seconds and hours. Most minor planets have rotation periods between 2 and 20 hours. , a group of 887 bodies – most of them are stony near-Earth asteroids with small diameters of barely 1 kilometre – have an estimated period of less than 2.2 hours. According to the Minor Planet Center, most small bodies are thought to be rubble pile In astronomy, a rubble pile is a celestial body that consists of numerous pieces of debris that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the various chunks that make the ...s – conglomerations of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LCDB Quality Code
In astronomy, a light curve is a graph of the light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the ''y''-axis and with time on the ''x''-axis. The light is usually in a particular frequency interval or band. Light curves can be periodic, as in the case of eclipsing binaries, Cepheid variables, other periodic variables, and transiting extrasolar planets; or aperiodic, like the light curve of a nova, cataclysmic variable star, supernova, microlensing event, or binary as observed during occultation events. The study of a light curve and other observations can yield considerable information about the physical process that produces such a light curve, or constrain the physical theories about it. Variable stars Graphs of the apparent magnitude of a variable star over time are commonly used to visualise and analyse their behaviour. Although the categorisation of variable star types is increasingly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid Belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers (or six hundred thousand miles) apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System. The asteroid belt is the smallest and innermost circumstellar disc in the Solar System. Classes of Small Solar System body, small Solar System bodies in other regions are the near-Earth objects, the Centaur (minor planet), centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids, and the Oort cloud objects. About 60% of the main belt mass is contained in the four largest asteroids: Ceres (dwarf planet), C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-type Asteroid
C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks and minerals. They have an average density of about . They lie most often at the outer edge of the asteroid belt, from the Sun, where 80% of the asteroids are of this type, whereas only 40% of asteroids at from the Sun are C-type. The proportion of C-types may actually be greater than this, since C-types are much darker (and hence sampling bias, less detectable) than most other asteroid types, except for D-type asteroid, D-types and others that lie mostly at the extreme outer edge of the asteroid belt. Characteristics Asteroids of this class have spectrum, spectra very similar to those of carbonaceous chondrite meteorites (types CI and CM). The latter are very close in chemical composition to the Sun and the primitive solar nebula minus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-type Asteroid
The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification, the X-group consists of the following types: * E-type – with high albedo (> 0.30), composed of enstatite, forsterite and feldspar. They are found in the inner main belt. * M-type – the largest grouping, intermediate albedo, "metallic", composed of iron and nickel, thought to be the progenitors of nickel–iron meteorites. They are found around 3.0 AU and in the Hungaria region (innermost main-belt). * P-type – low albedos (< 0.10) with featureless red spectra; presumably composed of carbonaceous chondrites, and found in the outer main-belt and the Jupiter trojan region. Since in this scheme, the albedo is crucial in discriminating between the above types, some objects for which albedo information was not available were assigned an X-type. An example of this is 50 Virginia. SMASS cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-type Asteroid
F-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-type asteroid#C-group asteroids, C-group. Characteristics F-type asteroids have spectra generally similar to those of the B-type asteroid, B-type asteroids, but lack the "water" absorption feature around 3 μm indicative of hydrated minerals, and differ in the low wavelength part of the ultraviolet spectrum below 0.4 μm. The F-type and B-type asteroids are not distinguishable with the criteria used in the asteroid spectral types#SMASS classification, SMASS classification, so in that scheme are grouped together under the B-type asteroid, B-type. See also *Asteroid spectral types References Asteroid spectral classes F-type asteroids (Tholen), * {{asteroid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S-type Asteroid
S-type (stony-type or silicaceous-type) asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are of this type, making it the second-most common after the carbonaceous C-type. Characteristics S-type 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 are 3 Juno (about 240–250 km across) and 15 Eunomia (230 km), with other large S-types being 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-Earth Object
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun ( perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about a third of a percent are comets. There are over 37,000 known near-Earth asteroids (NEAs) and over 120 known short-period near-Earth comets (NECs). A number of solar-orbiting meteoroids were large enough to be tracked in space before striking Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid Spectral Types
An asteroid spectral type is assigned to asteroids based on their reflectance spectrum, color, and sometimes Astronomical albedo, albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not planetary differentiation, internally differentiated, the surface and internal compositions are presumably similar, while large bodies such as Ceres (dwarf planet), Ceres and 4 Vesta, Vesta are known to have internal structure. Over the years, there has been a number of surveys that resulted in a set of different taxonomic systems such as the Tholen classification, Tholen, SMASS classification, SMASS and #Bus–DeMeo classification, Bus–DeMeo classifications. Taxonomic systems In 1975, astronomers Clark R. Chapman, David Morrison (astrophysicist), David Morrison, and Ben Zellner developed a simple taxonomic system for asteroids based on color, albedo, and spectral line, spectral shape. The three categories were labelled "C-type asteroi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid Family
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other. General properties Large prominent families contain several hundred recognized asteroids (and many more smaller objects which may be either not-yet-analyzed, or not-yet-discovered). Small, compact families may have only about ten identified members. About 33% to 35% of asteroids in the main belt are family members. There are about 20 to 30 reliably recognized families, with several tens of less certain groupings. Most asteroid families are found in the main asteroid belt, although several family-like groups such as the Pallas family, Hungaria family, and the Phocaea fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation Period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars ( inertial space). The other type of commonly used "rotation period" is the object's '' synodic rotation period'' (or ''solar day''), which may differ, by a fraction of a rotation or more than one rotation, to accommodate the portion of the object's orbital period around a star or another body during one day. Measuring rotation For solid objects, such as rocky planets and asteroids, the rotation period is a single value. For gaseous or fluid bodies, such as stars and giant planets, the period of rotation varies from the object's equator to its pole due to a phenomenon called differential rotation. Typically, the stated rotation period for a giant pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amor Asteroid
The Amor asteroids are a group of near-Earth asteroids named after the archetype object 1221 Amor . The orbital perihelion of these objects is close to, but greater than, the orbital aphelion of Earth (i.e., the objects do not cross Earth's orbit), with most Amors crossing the orbit of Mars. The Amor asteroid 433 Eros was the first asteroid to be orbited and landed upon by a robotic space probe (NEAR Shoemaker). Definition The orbital characteristics that define an asteroid as being in the Amor group are: * The orbital period is greater than one year; i.e., the orbital semi-major axis (''a'') is greater than 1.0 AU (''a'' > 1.0 AU); * The orbit does not cross that of Earth; i.e., the orbital perihelion (''q'') is greater than Earth's orbital aphelion (''q'' > 1.017 AU); * The object is a near-Earth object (NEO); i.e., ''q'' < 1.3 AU. Populations As of January 2025 there are 15,175 known Amor asteroids. Of those objects, 1414 are numbered, 83 are named, a ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
