Telescopes quiz

Stars twinkle because moving air in Earth's atmosphere disturbs their light.

Why do astronomers build telescopes with bigger and bigger mirrors?

Light-gathering power is proportional to collecting area, which grows with the square of the diameter. How many times more light does an 8-metre telescope collect than a 2-metre telescope?

Why must X-ray telescopes be placed in space?

Space telescopes are used mainly because they are closer to the stars.

Why are space telescopes such as Hubble and Webb reflectors rather than refractors?

NASA gives Webb's primary mirror a collecting area of 25.37 m² and Hubble's 4.55 m². How many times more light does Webb collect? Give one decimal place.

A single radio dish has poor resolution compared with an optical telescope of the same size. Explain why, and how radio astronomers overcome it.

Weigh the main trade-offs between a large ground-based telescope with adaptive optics and a space telescope such as Webb.