Space is full of enigmas that reveal science. Stars, supernovae, moons and planets, whose properties hold the secrets of the origin of the universe . One of the most famous and numerous inhabitants of space are asteroids.
Protagonists of disaster cinema, asteroids are rocky, airless remains that have persisted since the formation of the solar system , 4.6 billion years ago. They orbit the Sun, as do the planets.
But there are many more. According to NASA data, there are more than a million asteroids in our neighborhood . Specifically 1,097,148, and the vast majority are found in the so-called main asteroid belt, located between Mars and Jupiter.
The main belt is the most populated place. Although there are also asteroids that share an orbit with a larger planet , but without colliding with it. They are known as Trojans. There, the gravitational pull of the Sun and planet is balanced by the Trojan’s tendency to deorbit.The great Jupiter is the planet that has the most Trojans around it and it is believed that there are as many as in the asteroid belt. There are also Trojans from Mars and Neptune, and in 2021 NASA discovered a Trojan around our planet .
Near Earth Asteroids (NEO) are another category of asteroid . They are those that have orbits that pass close to our planet. Those who cross our path are known as Earthcrossers .
Variety of sizes, shapes and colors
There are asteroids of various sizes. Vesta is one of the largest, at 530 km in diameter, it is almost completely spherical and has a crust, mantle and core . It is in the asteroid belt, about 400 million kilometers from the Sun.
Others are much smaller, just 10 meters wide. They have irregular shapes, similar to teeth, with craters and holes .
“ More than 150 asteroids are known to have a small companion moon (some have two). There are also binary asteroids, in which two rocky bodies of similar size orbit each other, as well as triple asteroid systems,” says NASA.
Although there are many of them, and of different sizes, the total mass of all the asteroids together would not be equal to that of our Moon .
According to their composition, asteroids are classified into three types.
- Type C : these are the most common. They are dark and composed of clayey and silicate rocks. They are among the oldest objects in the solar system.
- Types S : (“stony”) composed mainly of silicate and nickel-iron.
- Types M: are metallic (nickel-iron).
The composition is linked to the distance from the Sun at which they formed. Some experienced very high temperatures after formation and partially melted.
Several NASA missions have flown to observe them and even collect samples from their surface. In 2001, the NEAR Shoemaker spacecraft landed on Eros , a near-Earth asteroid. Ten years later, the Dawn probe traveled to the asteroid belt to orbit and observe Vesta.
In 2016, the OSIRIS-REx spacecraft studied the near-Earth asteroid called Bennu and managed to collect dust and rock samples from its surface, which revealed high carbon and water content, basic components of life on Earth .
In September 2022, a historic event arrived for humanity. The DART mission was the first “planetary defense” test in which NASA managed to hit the asteroid Dimorphos , fragmenting it into pieces and thus diverting its trajectory.
“Everything we do at NASA seeks to answer questions about who we are and where we come from,” NASA Administrator Bill Nelson said at the time.