The word asteroid it means “star figure”. An asteroid is a body smaller than a planet and larger than a meteorite. It can be rocky, carbonaceous or metallic. Asteroids revolve around the sun and their orbit is interior to that of Neptune. In other words, they belong to the Solar System. For instance: Apollo, Ceres, Hermes, Juno.
Most of the asteroids are found in a strip between the orbits of Mars and Jupiter, known as the asteroid belt. However, there are also other asteroids close to Jupiter and a large number that cross the orbits of the other planets.
The size of asteroids is highly variable. The largest known is 1,000 kilometers long, while other asteroids are ten meters long. Ceres is the largest asteroid.
Its shape is relatively spherical.
Asteroids are rarely seen with the naked eye from Earth. However, this is possible in the cases of some asteroids close to our planet, in addition to Vesta, an asteroid of more than 500 kilometers, located in the main belt.
Asteroids can be classified according to various parameters:
- Location. Its relative position with respect to the sun and the planets. This distance is measured in Astronomical Units (AU). One AU is equivalent to the average distance between the Earth and the sun.
- Composition. It is determined thanks to absorption spectra.
- Grouping. They are based on the values of: semi-major axis, eccentricity and inclination of the orbit.
To study asteroids and other celestial bodies a measurement called “Absolute magnitude” which is the apparent magnitude that it would have at a distance of 10 parsecs in a completely empty space. This measurement is used because it is directly related to the luminosity of celestial bodies, regardless of their distance from Earth. For this reason, in some cases certain specific data about some asteroids (such as the diameter) have not been discovered, but their absolute magnitude is always known.
Examples of asteroids
- Apophis (also called 2004 MN4) (Aton asteroid: distance from the sun less than 1 AU). Discovered in 2004. Absolute magnitude: 19.7. Diameter: 0.325 km.
- Apollo (distance from the sun greater than 1 AU, and crosses the orbit of the Earth) Discovered in 1932. Absolute magnitude: 16.25. Diameter: 1.5.
- Bohlinia (main belt asteroid) From the coronis family. Discovered in 1911. Absolute magnitude: 9.6. Diameter: 33.73 km.
- Ceres (main belt asteroid). Discovered in 1801. Absolute magnitude: 3.34.
- Claudia (main belt asteroid) Discovered in 1891. Absolute magnitude: 10. Diameter: 24.05 km.
- Cruithne (distance from the sun less than 1 AU) Discovered in 1986. Absolute magnitude: 15.10. Diameter: 24.05 km.
- Gives life (main belt asteroid) Discovered in 1903. Absolute magnitude: 6.22. Diameter: 5 km.
- Dresda (main belt asteroid) Discovered in 1886. Absolute magnitude: 10.2. Diameter: 23.24 km.
- Elvira (main belt asteroid) Discovered in 1888. Absolute magnitude: 9.84. Diameter: 27.19 km.
- Eros (close to Earth): it is part of the Amor asteroids. Discovered in 1898. It measures 33 km, with an elongated shape.
- Eunomia Discovered in 1886. Absolute magnitude: 5.28. Diameter: 255 km.
- Europe (main belt asteroid) Discovered in 1858. Absolute magnitude: 6.31. Diameter: 302.5 km.
- Florentina (main belt asteroid) Discovered in 1891. Absolute magnitude: 10. Diameter: 27.23 km.
- Ganymede (close to Earth) is part of the Amor asteroids. Discovered in 1924. Absolute magnitude: 9.45. Diameter: 31.66 km.
- Gaspra (type s asteroid) (main belt asteroid) Discovered in 1916. Absolute magnitude: 11.46. Diameter: 12.2 km.
- Hathor (Aton asteroid: distance from the sun less than 1 AU). Discovered in 1976. Absolute magnitude: 20.2. Diameter: 0.3 km.
- Hermes (also called 1937 UB) (Asteroid Apollo: distance from the sun greater than 1 AU, and crosses the orbit of the Earth) Discovered in 1937. Absolute magnitude: 17.5.
- Hygieia (main belt asteroid) Discovered in 1849. Absolute magnitude: 5.43. Diameter: 407.1 km.
- Hilda (outer belt asteroid) Discovered in 1872. Absolute magnitude: 7.48. Diameter: 170.6 km.
- Hungaria (inner belt asteroid) Discovered in 1858. Absolute magnitude: 11.21.
- Icarus (Asteroid Apollo: distance from the sun greater than 1 AU, and crosses the orbit of the Earth) Discovered in 1949. Absolute magnitude: 16.9. Diameter: 1 km.
- Going (main belt asteroid) From the Coronis family. Discovered in 1884. Absolute magnitude: 9.94. Diameter: 32 km.
- Interamnia (main belt asteroid) Discovered in 1910. Absolute magnitude: 5.94. Diameter: 316.6 km.
- Juno (main belt asteroid) Third asteroid discovered, one of the largest in the main belt. Discovered in 1804. Absolute magnitude: 5.33. Diameter: 233.9 km.
- Koronis (main belt asteroid) From the Coronis family. Discovered in 1876. Absolute magnitude: 9.27. Diameter: 35.4 km.
- Khufu (also called Cheops) (Aton asteroid: distance from the sun less than 1 AU). Discovered in 1984. Absolute magnitude: 18.3. Diameter: 0.7 km.
- Tearful (main belt asteroid) From the Coronis family. Discovered in 1879. Absolute magnitude: 8.96. Diameter: 41.33 km.
- Nassovia (main belt asteroid) From the Coronis family. Discovered in 1904. Absolute magnitude: 9.77. Diameter: 33.1 km.
- Pallas (main belt asteroid) One of the largest in the solar system. Discovered in 1802. Absolute magnitude: 4.13. Diameter: 545 km.
- Chiron (Between the orbits of Saturn and Uranus). Discovered in 1977. Absolute magnitude: 6.1. Diameter: 166 km.
- Sisyphus (Asteroid Apollo: distance from the sun greater than 1 AU, and crosses the orbit of the Earth) Discovered in 1972. Absolute magnitude: 12.4. Diameter: 8.48 km.
- Toutatis (potentially dangerous asteroid due to its approach to Earth)
- Urda (main belt asteroid) From the Coronis family. Discovered in 1876. Absolute magnitude: 9.1. Diameter: 39.94 km.
- Vesta (main belt asteroid) Discovered in 1807. Absolute magnitude: 3.2. Diameter: 530 km.