Building a Universe
This is a galaxy it is made up of many particles. Planets are also made up of many particles. Galaxies are home to thousands of planets and stars. Earth itself would just be a tiny speck in our galaxy the Milky Way.
After the big bang, dust and rocks and gases all floated through the air until they collided and stuck together and slowly got bigger and bigger. And that's how the planets were created. Mars has a thin atmosphere. Water evaporates at low temperatures. There is no life on Mars because there is no water.
After the big bang, there was only hydrogen in space. Then the hydrogen collided and started to form balls of gas and so stars were made.Did you know stars have made everything in the universe, because, over time, they make things like carbon which goes into oxygen which goes in to iron and so on. Then when the star gets old it will go super nova and explode, scattering dust and particles throughout space.