Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: the fact that stars are made up of very lightweight hydrogen gas. Answer: hydrogen

Answer: What type of gas are stars made up of?

Question: Passage: Telescopes on Earth all have one big problem: incoming light must pass through the atmosphere. This blocks some wavelengths of radiation. Also, motion in the atmosphere distorts light. You see this when you see stars twinkling in the night sky. Many observatories are built on high mountains. There is less air above the telescope, so there is less interference from the atmosphere. Space telescopes avoid problems from the atmosphere completely since they orbit outside the atmosphere. Answer: the atmosphere

Answer: Many observatories are built on high mountains to avoid interference from what?

Question: Passage: A gas is a form of matter that has neither a definite shape nor a definite volume. A gas takes up the shape and volume of its container. This is because the particles of a gas are very far apart from one another compared to the particles that make up solids and liquids. Gases are easily compressed because of the large spaces in between gas particles. Gas particles are often invisible, but they can be detected in various ways, such as the light emitted when an electric current is passed through a sample of a gas ( Figure below ). Answer: gas

Answer:
What form of matter has neither a definite shape nor a definite volume?