Your answers to 10 tricky children's questions
Some interesting questions posed by children and some equally interesting answers.
2. HOW MUCH DOES THE SKY WEIGH?
Expert answer from the Science and Technology Facilities Council's Space Science and Technology Department: "If you want the total weight then it's about one millionth of the mass of the Earth, which is the equivalent of 570,000,000,000,000 adult Indian elephants."