The Solar System

The solar system is the Sun, plus everything that orbits it. That includes eight planets, five known dwarf planets, millions of rocky asteroids, icy comets, and countless tiny space pebbles called meteoroids.

If you spot something in the night sky that isn't a star or a faraway galaxy, it almost certainly lives right here in our solar system.

Everything orbits the Sun because of the Sun's gravity, the same gravity you've been learning about in every lesson. The eight planets travel in nearly circular paths. Comets and most smaller bodies follow long, stretched-out loops.

Here's the whole system. Click any object in the map, or use the search box on the right to look one up. Sizes and distances are not to scale. If they were, Earth would be a single pixel and the page would be miles long.

Until 2006 there were nine planets. Then astronomers agreed on three rules for what counts as a planet, and Pluto got kicked out into a new group called dwarf planets.

When the solar system formed about 4.6 billion years ago, most of the dust and rock clumped together into planets. The bits that couldn't quite become planets are still drifting around. Those are the asteroids.

Most asteroids live in the asteroid belt, a wide ring between Mars and Jupiter. They come in every shape (lumpy, stretched, dumb-bell, even bone-shaped) and every size (from a single grain of dust to small worlds hundreds of kilometres wide).

Movies often show the belt packed with rocks, but the real belt is mostly empty space. Spaceships fly through it just fine.

A comet is a chunk of ice, dust and rock. Basically a dirty snowball. Most of the time, comets sit way out in the cold edge of the solar system. Every now and then, gravity pulls one inward.

As a comet gets close to the Sun, its ice boils into gas. That gas and dust stream off the comet and form a glowing tail.

Same rock, three different names. The name depends on where the rock is on its journey to Earth. Press play to follow one all the way down.

From biggest to smallest:

• The Sun — a star. Its gravity holds everything else together.
• Planets — eight of them. Each one is the only big body in its orbit.
• Dwarf planets — round, but share their orbits with lots of other rocks.
• Asteroids — rocky leftovers, mostly between Mars and Jupiter.
• Comets — icy snowballs that grow tails when they get close to the Sun.
• Meteoroids — the smallest pebbles. They become a meteor when they streak through the air, and a meteorite when they land.

Drag any card into the right bin, or tap a card and then tap a bin. Sort all of them to win.