Space Rocks

Space rocks like asteroids form when microscopic grains of stardust and gas in a spinning protoplanetary disk around a young star cool, stick together, and slowly collide over millions of years to build larger rock bodies called planetesimals.

A helpful animation showing how dust and gas gather to form early space rocks:

From Stardust to Pebbles

Stardust ingredients: Dying stars and supernovas blast heavy elements like iron, silicon, and magnesium into the universe.

Cloud collapse: Gravity pulls these gas and dust clouds together, forming a flat, spinning disk around a new star.

Condensation and sticking: As the material cools, tiny mineral grains stick together to form pebbles.

Growing Into Larger Bodies

Accretion: Pebbles crash and fuse together like sticky snowballs, growing into mile-wide rocks.

Planetesimals: These larger chunks gravity-pull more debris, forming massive space rocks.

Leftovers: Gravity from giant planets prevents some debris from forming planets, leaving fields of space rocks like the asteroid belt.

Main Categories in Space

Asteroids: Large, rocky chunks left over from when the solar system formed. Most live in the asteroid belt between Mars and Jupiter.

Comets: Icy bodies made of frozen gases, rock, and dust. When they get close to the sun, they heat up and grow a bright tail.

Meteoroids: Tiny pieces of broken asteroids or comets floating out in space.

NASA

Terms for Rocks Near Earth

Meteors: A meteoroid that enters Earth's atmosphere and burns up. People call this a shooting star.

Meteorites: A meteoroid that does not burn up completely and lands on the ground.

YouTube

Types of Meteorites Found on Earth

Stony: Made mostly of silicate minerals; the most common type found.

Iron: Made of iron and nickel metal; very heavy and magnetic.

Stony-Iron: A rare mix of both stone and metal.

Why Space Rocks MatterSolar System History: Scientists study them as ancient time capsules from the birth of the solar system.Origins of Life: They may have brought early water and organic building blocks to our planet.Planetary Defense: Space agencies track potential impactors to keep Earth safe.

Types of Space RocksAsteroids: Large rocky chunks that orbit the sun, mostly found in the asteroid belt between Mars and Jupiter.Comets: Icy objects made of frozen gases, rock, and dust that grow bright tails when they near the sun.Meteoroids: Smaller pieces of space debris or broken asteroids and comets.Meteors: Meteoroids that enter Earth's atmosphere and burn up, creating a bright streak of light known as a shooting star.Meteorites: Space rocks that survive the fiery trip through the atmosphere and land on the ground.