Â鶹ÒùÔº

Meteorite challenges the timeline of the early solar system

A small, inconspicuous meteorite may be about to change our understanding of how and when our solar system formed. Tiny shavings from the meteorite Northwest Africa 12264 are challenging the long-held belief that planets near the sun formed earlier than those beyond the asteroid belt, between Mars and Jupiter.

Research by Dr. Ben Rider-Stokes from The Open University in Milton Keynes, UK, in Communications Earth & Environment, suggests that rocky planets in the inner and outer solar system formed at the same time.

According to current knowledge, planets are formed when a swirling disk of gas around a young star starts to clump together. This process is called accretion. Later, the material heats up and differentiation takes over to form a planet´s distinct layers, such as the core, mantle and crust.

Both these processes were thought to have occurred at different times in the early solar system—about 4.566 billion years ago for the inner protoplanets and 4.563 billion years ago for the outer protoplanets. Rocky planets further away from the sun were believed to have formed slightly later because they contained more water and ice. This would have slowed down the melting of their inner core.

However, studies of the 50-gram meteorite, which was purchased from a dealer in Morocco in 2018, tell us something different.

Challenging the timeline of the early solar system

First, the Open University researchers proved the meteorite came from the outer part of the solar system based on its ratio of chromium and oxygen. These vary in predictable ways in our solar system. Then, by measuring the meteorite's lead isotopes, they determined its age to be approximately 4.564 billion years, similar to inner solar system basalts, which are present in planetary crusts.

This finding could mean that rocky planets beyond Jupiter formed just as rapidly and concurrently with the inner planets.

"Our findings are consistent with observations of exoprotoplanetary disks that imply rapid planetesimal formation across radial distances," explained the researchers.

What it means for our Earth and beyond

While a difference of two or three million years may seem small in cosmological terms, it is enough to potentially reshape our understanding of how planets formed in the early solar system.

But the implications of this new research don't stop there. The more we understand about what happened in our cosmic backyard, the better we can apply this knowledge to the origin of our own planet and those in other solar systems.