How many planets circle the sun? -- What holds our solar system together? -- What planet has the shortest year? -- What is the hottest planet in our solar system? -- Why is there life on Earth? -- Why are there footprints on the moon? -- Are there volcanoes on Mars? -- How wide is the asteroid belt? -- What is the biggest planet in our solar system? -- How did Saturn get its rings? -- Which planet used to be named George? -- What planet has a cloud named Scooter? -- What are dwarf planets? -- Are there glowing snowballs in space? -- Are there other planets beyond our solar system?.