OM DENNE EPISODE
The oldest objects on Earth didn’t come from our home planet. They were born in space more than four-and-a-half billion years ago. They fell to Earth as the most common type of meteorite.
Chondrites account for about 85 percent of all meteorites. They’re named for tiny round beads of material known as chondrules. The beads formed in the disk of gas and dust that encircled the newborn Sun. Grains of dust clumped together. The chondrules then mixed in with other particles to form asteroids. Collisions sent pieces of the asteroids racing off into space. Some of them plunged through Earth’s atmosphere, falling as meteorites.
Chondrites haven’t changed much since they formed, so they preserve a record of the early solar system. They tell us what kinds of materials came together to form Earth and the other planets.
There are three main classes of chondrites. The differences reveal where they formed. Some were born quite close to the Sun; others, near the inner edge of the asteroid belt; and still others even farther out. The different classes tell us about conditions in different regions of the early solar system.
Many chondrites contain a lot of water, so they may provide clues to the origin of water on Earth. And they contain some of the chemical building blocks of life, perhaps telling us about the origin of life itself – lessons from relics from the birth of the solar system.
More about meteorites tomorrow.
Script by Damond Benningfield
