You are probably familiar with what the solar system looks like today. There are eight officially recognized planets that are more or less in the same plane and orbit the sun. But have you ever thought about what it looked like billions of years ago? Back then, things were very different.
We used to think that the early solar system looked a bit like a dartboard, with concentric rings of material circling our sun. But a team of researchers now suggests that the early solar system actually looked more like a doughnut. They’ve determined this using a rather unlikely source: iron meteorites.
Us solar system formed about 4.6 billion years ago, when a rotating cloud of dust and gas – the solar mist — collapsed into itself, and formed the sun. But not all of that dust and gas became our star. The leftover material continued to swirl chaotically around the sun, eventually condensing into planets and asteroidsThis cosmic nursery is known as a protoplanetary disk.
Although we cannot physically look back time As our solar system formed, we can see other examples of protoplanetary disks elsewhere in the universe the universeand many of them show these concentric circles of material. And we originally thought that the solar system might have looked like that.
But UCLA researchers found clues in iron meteorites that suggested otherwise. Iron meteorites come from the metallic cores of ancient asteroids that formed in the early years of the solar system, so they can give us insight into how the solar system formed. What caught the researchers’ attention were refractory metals like iridium and platinum, which were abundant in meteorites from the outer disk of the early solar system.
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That composition puzzled them. Those metals, which condense at high temperatures, should have formed closer to the sun, not in the cold regions of the solar system. And if our solar system had a dartboard-like structure, these metals shouldn’t have been able to “jump” from ring to ring to end up in the outer disk. So the researchers came up with a new theory about the shape of the early solar system: it looked more like a doughnut, a shape that allowed refractory metals to move outward as the disk expanded.
But then they ran into another problem. gravity of the sun should have drawn these heavier metals back toward it over the past few billion years — but it didn’t. However, the team also came up with a possible solution for that.
“Once Jupiter formed, it most likely opened a physical gap that trapped the iridium and platinum metals in the outer disk and prevented them from falling into the Sun,” planetary scientist Bidong Zhang, lead author of a new study on the meteorite analysis, said in a rack.
“These metals were later incorporated into asteroids that formed in the outer disk,” added Zhang, a planetary scientist at the University of California, Los Angeles. “This explains why meteorites that formed in the outer disk — carbonaceous chondrites and carbonaceous iron meteorites — have much higher iridium and platinum contents than their counterparts in the inner disk.”
And there you have it. Our solar system was once a doughnut-shaped protoplanetary disk filled with heavy metal before slowly morphing into the multiplanetary system it is today.
The study was published online May 28 in the journal Proceedings of the National Academy of Sciences.