How does a telescope work?

Introduction References & Edit History Related Topics

Images

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

Galileo's telescopes

Side-by-side comparison of the Carina Nebula, with the James Webb Space Telescope image on the left showing sharp, detailed stars and gas clouds, and the Hubble image on the right with softer, more diffuse colors.

Comparison between the Hubble and Webb space telescopes.

How does a telescope work?: References & Edit History

Article Contributors

Primary Contributors

Elijah Tan

Other Encyclopedia Britannica Contributors

Article History

Type	Description	Contributor	Date
	Article title updated for style.	The Editors of Encyclopaedia Britannica	Nov 09, 2026
	Added media.	Rick Livingston	Sep 24, 2026
	Added diagram of reflecting and refracting telescopes.	Erik Gregersen	Aug 25, 2026
	New article added.	Erik Gregersen	Aug 18, 2026