Who is Apollo's rival?

What are three main fuels that stars use as fusion? Is the earth weigh less now than 2000 years ago? What is earth orbiting the sun? Why is space exploration important to man? Which moon is too cold for liquid water to exist on the surface? Do robots work in space? What are the minor gases on Neptune? What is the term for the condition of the atmosphere in a given area at a given time? Does your solar system have 11 planets? What makes earth a good planet to live on? Which way do storms in the northern hemisphere rotate? What inner planet has the thickest atmosphere? How does a periscope use light? What is the name of the space agency created by the government in 1958? What is it called when you study space and stars? Why do we always see the same side of the moon from Ears? Can you become a mermaid when the full moon is out? What did charlie duke discover on the moon? What was the purpose of the NASA Explorer 9 mission? What was the earliest form of a hot air balloon look like?