What is the scientific term for sky?

Why are some mountains taller than the other? What project began the US' effort to reach the moon? How does a cloudy night and a clear night relate to the greenhouse effect? What are 5 colors and their corresponding Frequency and Wavelength? How does the speed of a planet depends on its distance from the sun? Does a vacuum cleaner work in space? Does Jupiter have a hot interior? What maria did Apollo 11 land on? Why did roger bacon invent the magnifying glass? Does the earth rotate in a circle around the sun or a oval? What was April 17 2014 moon? What method is Mario using? How does a space probe leave earth's gravity and travel to outer space and what does it pass through? How many atoms are in the solar system? Which planet has a greater mass than the combined mass of all the remaining planets and their moons? How do they land a hot air balloon? What is the sun made up of that other stars are made of? What are stalactites and stalagmites are examples? Composition of the atmosphere of Neptune? What does a star mean at the end of a sentence?