The solar system as we know it today began to form approximately 4.6 billion years ago, when the Sun and its planets emerged from the collapse of a massive cloud of interstellar gas.
The early years of our solar system remain shrouded in mystery. But by studying the vast number of meteorites that have fallen to Earth over these years, scientists are discovering intriguing clues about how planets formed and evolved over billions of years.
As detailed in the article published in the journal Earth and Planetary Science Letters , Scientists claim to have discovered evidence of an ancient world, possibly the size of the Moon or even Mars, that orbited the young Sun billions of years ago. This discovery suggests an entirely separate evolutionary path for a completely different class of planets than those with which we share the Solar System today.
«"It's incredible to imagine that such a vast world once existed," said study co-author and University of Colorado Boulder associate professor Aaron Bell. "We only know of its existence because a few fragments of it accidentally fell to Earth. These meteorites preserve evidence of a completely different developmental path for the early planets.".
Bell and his colleagues analyzed a meteorite weighing about half a kilogram, dubbed Northwest Africa (NWA) 12774, which was discovered in the Sahara Desert in 2019.
This rock is an angrit, one of the rarest types of meteorites, which scientists believe formed just millions of years after the birth of the solar system. It contains only traces of silicon dioxide, or silica, an extremely common component of the rocky planets orbiting the sun today.
Bell's team discovered a mineral crystal called clinopyroxene, rich in aluminum, within it, suggesting it formed under immense pressure and was possibly buried hundreds of kilometers deep. However, these crystals retained their sharp edges, a characteristic that would be lost at such depth, suggesting it formed within a very large body, yet relatively close to the surface.
According to their calculations, the diameter of NWA 12774's parent body could have been between 1,118 and 2,050 miles. For comparison, the Moon's diameter is about 2,100 miles, and Mars's is about 4,200 miles.
«"The materials that formed the parent body of angrit are fundamentally different from those found on Earth and Mars," Bell said in a statement. "This points to a distinct and independent evolutionary pathway for planet formation early in the history of our solar system.".
Many questions remain. First, we don't know how such a parent body ultimately perished, scattering its fragments across the solar system and ending up in the Sahara Desert. Scientists speculate that the early planet may have broken up into pieces, each of which eventually accumulated enough material to later evolve into the fully formed planets we know today.
In short, this is a fascinating glimpse into the earliest days of the Solar System, and we're only just beginning to understand how planets formed over billions of years. The study also suggests that there may be many other alien parent bodies in the universe that have yet to be discovered.
«"Many meteorites sit in boxes without being carefully studied, so there are probably many more of these protoplanets that we don't know about," Bell concluded.
More about planet formation: Scientists have discovered something in space that resembles a ring-shaped "planet factory.".