Refracting telescope
Lens-based telescope that opened telescopic astronomy.
Overview
Galileo's turn of a lens telescope toward the sky in 1609–1610 converted a novelty into a research instrument. Refractors revealed the Moon's rugged surface, Jupiter's moons and Saturn's rings, inaugurating four centuries of telescopic astronomy.
Key discoveries
- Galilean moons of Jupiter
- Phases of Venus and lunar mountains
- Saturn's ring resolved as a disk feature