Optical Telescopes: Gathering Light from the Stars

Optical telescopes collect visible light to magnify and study distant celestial objects.
The first practical designs appeared in the early 1600s, pioneered by Hans Lippershey and Galileo.
There are two main types: refractors (using lenses) and reflectors (using mirrors).
Galileo’s telescope revealed Jupiter’s moons, Saturn’s rings, and phases of Venus.
Modern telescopes use giant mirrors, some over 30 meters wide, to gather faint light.
Adaptive optics cancel Earth’s atmospheric blurring, producing sharper images.
Space-based optical telescopes, like Hubble, avoid atmospheric distortion altogether.
Large observatories, such as the Keck telescopes in Hawaii, have segmented mirrors for precision.
Optical telescopes help measure star positions, galaxy shapes, and planetary details.
From Galileo’s spyglass to mega-observatories, they remain humanity’s classic window to the cosmos.