Comets, Asteroids and Meteors

Not everything in our solar system is a planet. Billions of smaller objects orbit the Sun too — rocky asteroids, icy comets, and the streaks of light we call meteors. These leftover pieces are like the crumbs from when the planets were built, about 4.6 billion years ago.

It is easy to mix up these objects, so here is the trick. An asteroid is a chunk of rock or metal in space. A meteoroid is a much smaller piece of rock. A meteor is the flash of light we see when a meteoroid burns up in our air. And a meteorite is a piece that survives the fiery fall and actually lands on the ground.

Comets are lumps of ice, dust, and rock — sometimes called 'dirty snowballs' — that travel in long stretched-out orbits. When a comet swings close to the Sun, the ice warms and turns straight into gas, releasing dust that forms a glowing tail. This tail always points away from the Sun, pushed by the solar wind — so on the way out, a comet travels tail-first!

When tiny pieces of space rock enter Earth's atmosphere, they heat up from friction and burn, creating a bright streak of light called a meteor — or shooting star. On certain nights of the year you can see dozens of meteors per hour during a meteor shower. These showers happen when Earth ploughs through the dusty trail left behind by a comet.

Very rarely, a large asteroid can hit a planet. About 66 million years ago, a city-sized asteroid struck Earth and helped wipe out the dinosaurs. Today, scientists carefully track 'near-Earth objects' and have even tested ways to gently nudge a dangerous asteroid off course.