Between the orbits of Mars and Jupiter lies the asteroid belt, the main “habitat” for the relatively small bodies of the Solar System. Asteroids are quite heterogeneous in chemical composition, size, and origin. According to a new study, large belt bodies, such as Vesta, the brightest among them, did not initially originate where we see them now.

Many people are used to seeing the solar system as a clockwork mechanism, with its parts in place and moving in a precise orbit since its formation. That is, the compression of a cloud of gas and dust 4.5 billion years ago. However, in the past, planets could have collided, shifted each other, and migrated, changing the distance from their orbits to the Sun. It turns out that some celestial bodies did not start their lives in the place where we observe them.

The same applies to asteroids – relatively small objects ranging in size from tens of meters (smaller objects are called meteoroids) to hundreds of kilometers. Or, if you include Ceres, which has now been given the title of dwarf planet, there are almost thousands of them.

Many of them may have had a complex migration history throughout the solar system in the past, say the authors of the new paper. Planetary Science Journal Applied computational modeling to reconstruct the initial state (primarily mass) of the main asteroid belt and find out where the largest ones, like Vesta, “came from.”

Let’s remind you: Vesta is the brightest asteroid visible from Earth, even with the naked eye. Its diameter is about 500 kilometers, but it varies because Vesta has an irregular shape.

The authors of the new scientific study emphasized that the population of the Main asteroid belt is heterogeneous. In it, primarily S-complex objects are distinguished, which were formed closer to the Sun, within the orbit of Jupiter. But representatives of the C-complex come from distant regions of the Solar System. The origin affected the chemical composition of two types of asteroids. The first has very little water, the second consists of 5-20 percent water and is also rich in volatile compounds.

Astronomers have created a complex model of the asteroid belt that depicts the solar system 500 million years after its formation. The model is computationally based and takes into account the dynamics of celestial bodies, their collisions and their growth through fusion.

Special attention was paid to neighboring planets, especially a weightlifter like Jupiter. In some cases, the gas giant was in different orbits or was not considered at all. This is important because past migrations of Jupiter away from the Sun and towards it could have affected the population of the Main Asteroid Belt due to its gravity.

The researchers set out to find out how big the original mass of the asteroid belt was. Scientists have different opinions on the subject: some believe that the original mass of the asteroid belt was much smaller, while others believe that it has not changed much. It is now extremely small, almost two thousand times smaller than Earth. And one third of it falls on Ceres and nine percent on Vesta. Not even a decent moon of the planet, let alone a planet, could be assembled from this material.

The paper shows that the mass of the asteroid belt was quite low from the beginning of its history. Otherwise, if the hypothesis of a much larger initial mass “review” is correct, we would observe tens of thousands of asteroids of similar size to Vesta. In fact, there are only a few of them.

According to simulations, individual radial sectors of the asteroid belt eventually lost their initial uniformity. Some of them turned out to be sparsely populated, while others acquired a noticeably larger total mass.

Astronomers have concluded that S-complex objects come from more distant regions of our planetary system. Therefore, they cannot be considered “indigenous inhabitants” of the asteroid belt. Most likely, in origin, these are planets of a terrestrial type, i.e. “microbes” from which planets were formed.

It is worth mentioning that Ceres, the largest object in the asteroid belt, which belongs to a different class, was also most likely not formed in modern orbit. Recently, astronomers suggested that it was formed in the orbit of Saturn, which explains the peculiarities of the chemical composition of the small planet.