Asteroids are rocky bodies located around the Sun. Their small size catalogs them as minor planets. Its name comes from the Greek, since asteroid means "star form" and they were so named for the first time by the British astronomer John Herschel (1738-1822).
Asteroids that are in the process of colliding with Earth are called meteoroids. When they only touch the atmosphere and are deflected by this, the friction produces a combustion on the surface that leaves a spectacular ray of light that we know as a meteor.
If the meteoroid is capable of being consumed when crossing the atmosphere it can leave residues of different sizes that we know as meteorites. If the bolide is very large, the impact could cause major climatic and orographic changes on the planet as it could happen with the extinction of dinosaurs.
In the formation of the solar system there were residues and, like the rest of the elements that make up the planets, the asteroids are formed by the material that the stars generate after their death.
The residual material that has not come to join any planet or satellite is orbiting. But the mass of all the asteroids united in a single object would not reach to form a small moon, half of ours, of about 1 500 km in diameter.
The image shows three scenarios in the evolution of asteroid belts in different solar systems. Above, asteroids are generated by material that spreads a Jupiter-sized planet that orbits across the asteroid belt. A scenario in which life is not possible.
The central sequence shows our own solar system with a large planet (in our case Jupiter) that orbits outside the asteroid belt.
Below, a massive asteroid belt that would impede the evolution of life.
Pallas, one of the largest asteroids in the solar system-the second to be discovered after Ceres, who with its 1,000 km in diameter is considered a dwarf planet-with 532 km in diameter at 50 meters. Recent studies establish between 1.1 and 1.9 million asteroids. Of the cataloged, only 16 have a diameter greater than 240 kilometers.
Most of the asteroids are clinging to what is known as the "main belt or asteroid belt", an orbit around the Sun, between Mars and Jupiter.
Some pass through Earth orbit, but of the known ones none has a trajectory of collision with Earth, although Earth's geological history seems to show that the impacts of asteroids are more frequent than desirable.
There are 800 Potentially Hazardous Asteroids (PHA, abbreviations that correspond to potentially hazardous asteroid). The damage caused in a collision with the Earth, can vary from local disasters to mass extinctions. One of the most accepted theories assures that the fall of asteroids on the planet caused a great extinction in the Permian that finished with 90 percent of the life on the Earth; as well as another great fireball that caused the disappearance of the dinosaurs at the end of the Cretaceous.
A good part of scientists thinks that life could reach the Earth on comet or asteroid backs that hit the planet and that they contributed complex carbon molecules with water and organic compounds in the primitive earth.
The image shows the Arizona crater is one of the best preserved on Earth, as a result of an impact of an asteroid 30 meters wide 50,000 years ago. Approximately 150 impact craters have been found throughout the planet.
The provisional name of an asteroid is awarded by the Center for Minor Planets (Minor Planet Center - MPC) in a somewhat convoluted way.
It consists of a number that is the year of discovery and a first letter that refers to the fortnight in which this sighting was made, according to an alphabet of 25 letters. A second letter indicates the order in which it was discovered during that fortnight. If the letters are finished, the numbers begin in sequence (A1 would be the 26th discovered, B1 corresponds to 27).
In the case of for example 2003 QQ47, we will know that it was discovered in 2003 in the second half of August (Q) and in the order 16 x 47 (the Q sixteenth letter by 47), that is to say it would be the 752nd asteroid discovered that fortnight .
When the orbit of the asteroid is established, it is assigned a number and a name chosen by its discoverer. Currently you can choose any name. That's why we can find asteroids that are called as rock stars (23990 Springsteen), cities (945 Barcelona), or fantastic characters (2309 Mr. Spock).
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