COUNCIL CHRONICLE – A paper published in Science Advances this week has proposed a new theory about the origin of the asteroid belt.
This region of space, also known as the main asteroid belt, lies between Mars and Jupiter. It is a massive disc that orbits around the Sun, similar to planets. From its position, it also serves as a sort of border between the inner, terrestrial planets (those that are solid and rocky, like Earth) and the outer gas giants.
Despite how asteroid belts are usually seen in fiction, such areas are very thinly populated. Altogether, the asteroids and dwarf planets make up only a thousandth of Earth’s mass. The predominant theory is that it was once far thicker, but that gravity from Jupiter flung 99 percent of its mass away to more distant parts of the solar system or even beyond it. This is also considered to be the reason why larger planets never formed there.
Asteroid Belt Formation Process Tied to Planets
Sean Raymond and Andre Izidoro of the Université de Bordeaux are behind this new study paper. They took a closer look at one factor that others have noted before. Namely, that asteroids closer to the terrestrial planets tend to contain silicates (referred to as “S-class asteroids”), like the terrestrial planets themselves. At the same time, such space rocks closer to the gas giants tend to contain more carbon (“C-class asteroids”), again like the gas planets do. To them, this seems to imply that the asteroids are made from the same material as the planets.
From this, Raymond and Izidoro have constructed a new theory: that the region between Mars and Jupiter was originally empty. But then the planets, on both sides, flung stray material from their formation into the area, thus causing the origin of the rocky region.
“The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself,” their paper explains.
To test this theory, the pair created a computer model that imitates the solar system during its early days (or millions of years) of formation. This leaves the region between Mars and Jupiter empty. Sure enough, the model demonstrated the possibility that the stray material from the other planets could have found its way into what is recognized today as being the asteroid belt. They plan to conduct further research to test this theory against the more conventional view, hoping to determine which version, if either, is correct.
Image Source: JPL/NASA