Ordovician meteor event facts for kids

The Ordovician meteor event was a time long, long ago when lots of space rocks, called L chondrite meteorites, fell to Earth. This happened during the Middle Ordovician period, about 467.5 million years ago. Scientists found proof of this by discovering many fossil meteorites in a quarry in Sweden. They also found tiny bits of space rock dust in ancient rocks from that time.

Paleogeography of the Middle Ordovician (~470 Ma)

What Caused This Space Rock Shower?

A Giant Asteroid Broke Apart

Scientists believe this huge increase in falling space rocks happened because a very large asteroid broke into many pieces. This asteroid was about 150 kilometers (93 mi) (93 miles) wide. It was orbiting in the asteroid belt, which is a busy area between Mars and Jupiter.

This big break-up happened around 468 million years ago. When the asteroid broke, many of its pieces were sent onto paths that crossed Earth's way. This idea is also supported by looking at how old impact marks are on many L chondrite meteorites that still fall to Earth today.

Did It Change Life on Earth?

Some scientists have thought that this shower of space rocks might have helped start, or at least added to, the Great Ordovician Biodiversification Event. This was a time when many new types of life appeared and grew on Earth. However, other scientists have questioned if the meteor event really had such a big effect.

A Ring System Around Earth?

A study from 2024 looked at 21 impact craters from this event. They found that all these craters were formed close to the equator, within 30 degrees. If the space rocks came directly from the asteroid belt, the craters should have been spread out randomly.

This finding suggests a different idea. It's possible that a large asteroid passed very close to Earth. It might have gotten so close that Earth's gravity pulled it apart. This could have created a ring system around Earth, similar to Saturn's rings.

Then, pieces from this ring system slowly fell out of orbit and crashed into Earth. This would explain why the craters were mostly near the equator. Some scientists even think that the shadow cast by this ring system might have helped cause the Hirnantian glaciation. This was a big ice age that happened later in the Ordovician period.

See also

• Österplana 065
• Lockne crater
• Målingen crater
• Pilot crater
• Tvären