The asteroid belt: wreckage of a destroyed planet or something else?
âIt’s like tiny crumbs,â Raymond says.
Just because the asteroid belt doesn’t represent the remnants of an ancient planet, doesn’t mean scientists have given up on the idea altogether. The belt could come from parts of other planets that still exist, or it could be part of a planetesimal – which is like a baby planet – that never fully formed until it was shattered.
âIt was a pretty simple story, but in recent years it’s gotten more and more complicated as we learn more about the formation of planets,â says Bottke.
Raymond says these pieces may have been left behind when Jupiter and Saturn were still forming. Later, these planets may have migrated around the solar system until they eventually reach their current orbits. This would have resulted in dynamic instability, with chaotic orbits and gravitational forces.
âThe solar system today is very different from what it was 4.5 billion years ago,â Bottke said.
Different puzzle pieces
We now know that the asteroid belt does not contain material from a single source. Some of its components may have been derived from the general region of space it currently inhabits. Other materials may come from sources beyond Jupiter’s orbit, Bottke says. Still other asteroids may have arrived from the area of ââthe inner planets, in the form of pieces that broke off at some point.
The movements of the planets during the solar system’s first period of instability could have caused the gravity of Saturn and Jupiter to suck up some of the matter, while sending other asteroids into other planets or out of our solar system. . Some researchers even believe that water-rich asteroids crashed into Earth during this time, creating the oceans we still have today. Raymond says that a fraction of these rocks would have been sent in the right path and the right speed to join the asteroid belt.
âIn this context, we sometimes call the asteroid belt the blood spatter of the solar system,â he says.
Whatever violence may have caused these pieces to send into the asteroid belt, the reason they stay put is because the orbits of Mars and Jupiter have finally stabilized. So if an asteroid manages to find its way there, it’s probably not going anywhere, says Bottke.
According to Raymond, the question of the solar system that preoccupies most astronomers is how the planets were formed. The composition of asteroids, their position and their orbits continue to reveal clues to the distant past of the planets.
âEven though we care more about planets than asteroids in general, asteroids are a very good tool in trying to figure out what happened with planets,â explains Raymond. “They really are a key piece of evidence in this story.”