Asteroid types and characteristics

The Solar system It is a planetary system in which we can not only have a multitude of objects: from stars to planets and dwarf planets, passing through satellites, minor bodies, etc. The smaller bodies include asteroids, comets and meteoroids.

In this lesson from a TEACHER we will review the different types of asteroids and their characteristics, one of the most interesting minor bodies, since, on many occasions, these fragments or complete bodies approach the atmosphere of our planet and even manage to cross it.

Index

1. What is an asteroid: short definition
2. Asteroid characteristics
3. Types of asteroids that exist
4. Main belt asteroids
5. Near Earth Asteroids
6. Trojan asteroids
7. Centaurs

The word asteroid comes from the Greek, and means "of star figure." At the beginning of the 19th century, William Herschel used it to define bodies seen through the telescope, although for most of the 19th century astronomers called them planets.

The definition of asteroid is as follows:

Asteroids are bodiesrocky, smaller than the planets, and orbiting the Sun. There are many asteroids in our solar system, although most of them are found in the asteroid belt, a region between the orbits of Mars and Jupiter.

For more than two centuries, Ceres was the first asteroid discovered, but after the planet redefinition of 2006, it reclassified this body as a dwarf planet. Therefore, it is Pallas, found in 1802, the first asteroid discovered. In this other lesson we will discover the differences between asteroid, meteorite and meteor.

Image: Slideshare

Now that you know the definition, we are going to discover the main characteristics of asteroids. The main difference between a planet and an asteroid is your size. Asteroids are much smaller than planets. Its size varies between 1000 km of the largest to rocks of just ten meters. Larger asteroids can be mistaken for dwarf planets and, in fact, some of them are strong suitors to be part of the future. Tiny planets.

The other big difference between asteroids and planets is their shape. The asteroids usually have jagged and irregular shapes. These "rare" forms are due to the fact that they have not had the opportunity to condense and become larger, and therefore have not achieved a sufficient turning force to have a rounded shape, typical of planets

Asteroids are surviving remains of the primitive planetths (primitive planets, now gone), or fragments of larger bodies produced after catastrophic collisions. Asteroids are the minor bodies that were once or never were planets.

Image: Slideshare

There are different types of asteroids that depend on the classification. There are 2 ways to classify them: the main two are according to their spectral types and according to their position within the Solar system.

The classification of asteroids according to their spectral types It is carried out by making a study of the light reflected by the asteroids, which provides indications of their surface compositions; This type of classification is very complex and not entirely accurate, since different materials can have similar absorption spectra and these are can be influenced by the state of the surface (porosity, fragmentation, existence of a layer of dust that covers the surface of the planet, etc). Therefore, in this lesson from a PROFESSOR we will see the classification of asteroids according to their distribution in the Solar System.

Attending to your position with respect to other bodies of the Solar System, mainly planets, asteroids are classified into:

• Near Earth asteroids.
• Main belt asteroids.
• Trojan asteroids.
• Centaurs

Sometimes when the definition of an asteroid is made, it is included that its position must be between Mars and Jupiter, in the region of the solar system known as the asteroid belt. The group of asteroids found in this region of space is called the main belt asteroids, but as we shall see, they are not the only ones in our Solar System.

The main belt asteroids are at a distance of 2 and 3.5 ua from the Sun. In this region there are, in addition to the dwarf planet Ceres, the largest known asteroids in the Solar System: Palas and Vesta. Furthermore, in the asteroid belt we find how Juno and Hygieia that, although they are smaller, they are not negligible.

The fragments of material contained in the belt region that currently form these asteroids would have been able to form a planet. They didn't because Jupiter, the most massive planet, has a great gravitational pull. This gravitational force produced a series of disturbances that caused these fragments to collide with each other at great speeds and could not be grouped, resulting in this set of rocky residues that form that peculiar belt.

Image: Universe blog

Near Earth Asteroids (NEA, Near-Earth Asteroids) are all those objects that have a orbit near Earth and are not comets. There are more than 10,000 known asteroids with these characteristics, and part of these bodies is believed to be the remains of extinct comets. Other NEAs are believed to originate in the asteroid belt where Jupiter's gravitational influence throws the inner solar system.

These asteroids have a composition similar to main belt asteroids and they can be subclassified according to their size and orbit in:

• Aton Asteroids
• Apollo Asteroids
• Asteroids Love
• Potentially dangerous asteroids

Trojan asteroids are asteroids that share orbit with a planet. The term of trojan asteroid was coined to name the asteroids that shared orbit with Jupiter since the convention was established to baptize the asteroids that occupied that place with the name of the Trojan War characters.

As the Solar System has been investigated, other Trojan asteroids have been found in the orbits of Mars, Neptune, etc. although most belong to the orbit of Jupiter. As of April 2010, more than 4,000 Trojan asteroids were known, and only ten do not belong to Jupiter.

exist two theories to explain its origin and location.

• The first indicates that they were formed during the last stage of planetary accretion or condensation in the same region in which they are found.
• The second establishes that, during planetary migration, the primitive Kuiper belt was destabilized and millions of objects were thrown into the inner solar system, where they were incorporated into the orbits of the planets gaseous.

Image: 100cia

Centaurs are a group of asteroids found in the Outer Solar System, orbiting Around the sun between Jupiter and Neptune, crossing the orbits of the gas giants. Some examples are: Chiron, which orbits between Saturn and Uranus and Damocles, which rotates between Mars and Uranus.

These bodies have unstable orbits, as they are highly gravitationally influenced by Jupiter's great mass and gravitational force.

The origin of the centaurs is still unclear, although some of them are believed to have also come from the expulsion of objects from the Kuiper Belt.

If you want to read more articles similar to Asteroid types and characteristics, we recommend that you enter our category of Astronomy.

• NASA (October 24, 2019) What is an asteroid? Recovered from: https://spaceplace.nasa.gov/asteroid/sp/
• Wikipedia (April 27, 2020) Asteroid. Recovered from: https://es.wikipedia.org/wiki/Asteroide
• Astronomy (s.f) The Asteroids. Recovered from: https://www.astromia.com/solar/asteroides.htm