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Telescope
1608 (Netherlands; priority disputed); Galileo 1609· Invention or discovery· Tools, energy & materials
DebatedHistorians or scientists disagree about what happened, when, or why.
An instrument using lenses or mirrors to make distant objects look closer, first offered for a patent in the Netherlands in 1608.
See it on the Technology & Medicine map →How it works
In September 1608 Hans Lipperhey, a spectacle maker in Middelburg, asked the Dutch government for a patent on a tube holding a convex and a concave lens that magnified about three times. Others claimed the same idea within weeks, so no patent was granted. Galileo heard of it in 1609 and built versions up to about 20 times. Kepler designed an improved two-convex-lens version in 1611, and Newton built a mirror telescope in 1668.
Why it mattered
It turned astronomy from naked-eye watching into study of objects no one had seen, supplying key evidence that Earth orbits the Sun. Armies and navies wanted it too.
How we know
Dutch government records of Lipperhey's October 1608 patent hearing; Galileo's Starry Messenger (1610) and his surviving telescopes in Florence; Newton's reflector, kept by the Royal Society.
Still unknown or debated
Who made the first telescope is disputed among Lipperhey, Jacob Metius and Zacharias Janssen; earlier, unrecorded lens experiments are possible.
Inside this (1)
Connections (2)
▸Eyeglasses led to the TelescopeMostly agreed
The connection
Spectacle makers spent three centuries learning to grind convex and concave lenses. In 1608 a Middelburg spectacle maker, Hans Lipperhey, put one of each in a tube and found distant objects looked about three times closer. The telescope came directly out of the eyeglass trade, which supplied both the lenses and the craftsmen.
When and how
Middelburg, the Netherlands, in 1608; Lipperhey and the other early claimants, Jacob Metius and Zacharias Janssen, all worked with lenses.
How sure are we?
The 1608 Dutch patent records describe Lipperhey as a spectacle maker, and the earliest telescopes used ordinary eyeglass-quality lenses.
Debates and open questions
Some suggest earlier lens combinations, such as Leonard Digges's in 1550s England, worked as telescopes; the evidence is thin.
▸Telescope was turned skyward by Galileo GalileiWell documented
The connection
Galileo heard of the Dutch spyglass in 1609 and, grinding his own lenses, built telescopes magnifying up to about 20 times. Turning them skyward, he saw lunar mountains, Jupiter's four largest moons, and later Venus's phases and sunspots, evidence against the old Earth-centered universe. He published his first findings in The Starry Messenger in March 1610.
When and how
Padua and Venice, 1609–1610; the Englishman Thomas Harriot sketched the Moon through a telescope a few months before Galileo but did not publish.
How we know
Galileo's 1610 book with its Moon drawings, his notes, his surviving telescopes in Florence, and other astronomers' confirmation of Jupiter's moons by 1610–11.
Debates and open questions
Priority for some discoveries, such as sunspots, is disputed with the Jesuit astronomer Christoph Scheiner and with Harriot.