Well Ellen thats a classic question! And still no one can really be sure!
The best ideas suggest that about 100 billion years ago, the Earth and the Universe and all the other planets were just clouds of dust particles in empty space. Over time, these particles became attracted to each other, and begin to form a massive disk, which spun extremely fast. As it spun so fast, it began to separate out into distinct rings, each building up huge amounts of energy. The middle of the disk became the sun, and the fast-burning particles on the outside began to turn into large balls of gas and molten-liquid that cooled and condensed to become a solid form.
After another few billions of years, these begin the planets of the solar system that we know, including Earth.
Nailed it Karen, and nice video too!
Scientists also think that once the earth was formed it was then hit by something really big (they’re not quite sure what) which caused it to break up into several chunks. One of these slowly became the moon that we know today and the other large chunks reformed into the earth that we know now.
The water on earth is also believed to have come from somewhere else, as it definitely wasn’t there when the earth was formed! It possibly came from other large meteorites with ice in them. Or somewhere else, who knows! Then once the molten mass of iron began to go hard in the middle this gave us our magnetic field around the planet, which is the most important thing about earth as it protects us from the solar radiation of the sun. Otherwise we’d be pretty crispy down here!