Asteroid belt

Asteroid belt
The asteroid belt and the related Jupiter Trojans.
Discovery Data
Discovered On	January 1, 1801
Discovered By	Giuseppe Piazzi
Characteristics
Width	~1 AU
Start Distance	2.2 AU
End Distance	3.2 AU
Objects Located In It	Probably over 1 million
Other
Planets In It	None
Dwarf Planets In It	Ceres Hygiea (dwarf planet candidate)
First Object In It Discovered	Ceres

The Asteroid Belt, also known as the Main Belt, is a three billion cubic-mile asteroid region in the Solar System located between the two planets Mars and Jupiter. It contains a moderate fraction of the asteroids that are found in the Solar System. Not only does this belt contain asteroids, but it also is home to the dwarf planet Ceres, the dwarf planet closest to our Solar System. This belt is constantly orbiting the Sun, along with the planets.

Formation

It is believed, that between the mars and Jupiter, in the early days of the solar system six planetesimals were orbiting. These collided, forming sub-dwarf planets ( like Vesta) and many small asteroids, which ones stay in asteroid families, few of the sub-dwarf planets collided to disruption, or just had an impact, forming other asteroid families, asteroid families formed also by gravitational grouping.

Ceres was probably brought to the asteroid belt after the big six collided, it also formed an asteroid family by gravitational pulls.

Kirkwood Gaps

Kirkwood gaps were discovered by Daniel Kirkwood in 1857. These are gaps that are caused by asteroids that have the same orbital period, or amount of time taken to orbit the Sun once. When the planet that formed the Asteroid belt was destroyed, some asteroids and fragments were shipped off into deep space, causing these "Kirkwood Gaps".

Composition

The composition of the asteroid belt varies depending on the distance at which the asteroids formed from the Sun. These distances bring us three distinct categories, or spectral types of asteroids that exist in this belt: carbonaceous, the most populous, metal-rich asteroids, and silicaceous asteroids.

Main Spectral Types

• Carbonaceous asteroids, also known as C-type asteroids, are the most populous asteroids in the asteroid belt. These asteroids appear much more darker than other asteroids. Carbonaceous asteroids are made up of clay and silicate rocks. These the oldest category of asteroids to exist in our solar system.
• Silicaceous asteroids, also known as S-type asteroids, on the other hand, are made up of silicate rocks and nickel-iron. These are typically lighter than carbonaceous asteroids.
• Metallic asteroids, also known as M-type asteroids, make up the least portion of the asteroid belt. These are mainly made up of mainly nickel-iron. These are most massive of the asteroids, due to their metal nature.

Other Spectral Types

• A-type asteroids (also known as olivine-rich asteroids) are relatively uncommon inner-asteroids with small amounts of olivine (a greenish mineral).
• D-type asteroids are asteroids with very low albedo and a featureless reddish spectrum. Most likely, they are comprised of mostly organic-rich silicates, carbon, and anhydrous silicates. They possible have water in their interiors.
• E-type asteroids (also known as enstatite asteroids) are asteroid with enstatite or achondrite surfaces. They form a large group of asteroids toward the inner belt (known as the Hungaria asteroids).
• P-type asteroids are asteroids that have a low albedo, and have a featureless reddish spectrum (similar to D-types). It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior.
• Q-type asteroids are a rare type of asteroid that commonly contain traces of olivine, pyroxene and metal. Only 20 of these asteroids have been found.
• R-type asteroids are an uncommon type of asteroid with a moderate albedo. There spectra shows olivene, pyroxene and traces of plagioclase. Their spectra are usually very red. Only 5 of these asteroids have been categorized.
• T-type asteroids are rare inner-belt asteroids of unknown composition with dark, featureless and moderately red spectra. No direct meteorite analog has been found to date. Thought to be anhydrous, they are considered to be related to P-types or D-types, or possibly a highly altered C-type.
• V-type asteroid (also known Vestian asteroids or Vestoids) are asteroids with a similar spectral type to that of the asteroid 4 Vesta.

V-type Near Earth Asteroids

V-type near Earth asteroids, known as V-NEAs are asteroids that are both of V-type and of proximity to Earth. 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.

Carbonaceous variants

• B-type asteroids (also known as blue-carbonaceous asteroids) are another uncommon type of carbonaceous asteroid that fall into the wider C-type of asteroids. There name come from the amount of blue in their spectral lines.
• F-type asteroids (also known as water rich carbonaceous asteroids) are an uncommon type of carbonaceous asteroid that is high in water content. This category used to be part of the B-type, until the two split.
• G-type asteroids (also known as mica-clay rich carbonaceous asteroids) are an uncommon type of carbonaceous asteroid that is high in phyllosilicate minerals, i.e. clay or mica.

Groups of Asteroids

Jupiter-related/Trojans

There are asteroids like the cybele a family asteroids or hilda family asteroids, which ones were disturbed by the Jupiter, they eventually became co-orbital with its L3,4, and 5 points, meaning, that during the aphelion, the objects are moving together with the L3, 4, or 5. These objects are still in orbital change, they will eventually become Jupiter trojans.

Near Earth Asteroids

Though not their formal name, near Earth asteroids follow the orbit of, around, or even travel inside the orbit of the Earth. Mainly referred to as the Apollo, Aten, Amor, and Adams asteroids, these are believed to have future impacts with the Earth within the next hundred thousand to million years. These make orbits within the ranges of Earth and Mars' orbital periods.

Many other asteroid families exist.

Main-Belt Comets

Main article: Periodic Comets

There are bodies located outside of the belt that are shown to have cometary action, or comet-related activity. Main-belt comets are thought to have been a major component in the creation of the Earth's oceans. They are shown to have high amounts of a substance known as deuterium-hydrogen, which cannot be found in regular comets.

Ceres

Main article: Ceres

Ceres is the only celestial object to be a dwarf planet and an asteroid. In fact, it is the only dwarf planet located in the Asteroid belt. In fact, it maintains hydrostatic equilibrium, which means it is barely massive enough to have even a trace gas in an atmosphere.

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