How Does Comets: Crash Course Astronomy #21 Work?

Comets are like dirty snowballs that zoom through space and sometimes crash into planets, including Earth.

Imagine you have a big ball made of ice, dust, and rocks. That’s what a comet is. When it gets close to the Sun, the heat makes the ice melt, creating a bright tail that shines in the sky. It's like when you leave an ice cream out in the sun, it starts to drip and look messy.

Comets zoom through space because they are pulled by gravity, just like how Earth pulls things down. The Sun’s gravity is strong enough to make comets follow a path, or orbit, around it. Sometimes, other planets can nudge them a bit, kind of like when you push a swing.

Sometimes comets come too close to a planet, and they crash into it. It's like if you threw a ball really hard at a wall, if you throw it just right, it might bounce back, but if you throw it too strong, it might break the wall!

Comets crashing can be a big deal, some scientists think one comet hit Earth a long time ago and caused a giant explosion. That helped shape our planet!