Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. What is beyond outer space? – Siah, age 11, ...

Add Yahoo as a preferred source to see more of our stories on Google. Right above you is the sky – or as scientists would call it, the atmosphere. It extends about 20 miles (32 kilometers) above the ...

Right above you is the sky – or as scientists would call it, the atmosphere. It extends about 20 miles (32 kilometers) above the Earth. Floating around the atmosphere is a mixture of molecules – tiny ...