The Big Bang created a cloud of dust and rocks that included a lot of rocks that were made of ice, like giant snowballs. That’s where some of the water came from.
The InSight Lander mission to Mars is preparing for launch in May 2018. But there are seven (or eight) other planets to explore: why have we such a hang up on Mars?
The moon might harbor bits of the Earth that blasted off our planet billions of years ago. These lunar time capsules could hold secrets about conditions here at home back when life was first emerging.