The earth wasn’t formed by aliens of just popped out of nowhere When the solar system settled into its current layout about 4.5 billion years ago. Earth was formed when gravity pulled swirling gas and dust in to become the third planet from the sun. Like its fellow planets it has a central core, a rocky mantle and a solid crust. When earth was first formed it didn’t look like the earth we see today it was full of volcanoes,lava and rocks.