How does a telescope work?: Quick Facts

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$Illustration comparing a reflecting telescope, which uses mirrors to focus light, and a refracting telescope, which uses lenses, both mounted on tripods and pointed at the night sky.$

Galileo's telescopes

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reflecting telescope refracting telescope telescope Telescope Radio telescope X-ray telescope Ultraviolet telescope Telescopes: Seeing Stars Infrared telescope Gamma-ray telescope Seeing Cassegrain reflector Heliostat