Galileo's telescope and the Sidereus Nuncius
- Date
- March 1610
- Category
- Science, technology & invention
- Region
- Italy (Padua / Florence)
- Era
- Early Modern
- Significance
In 1609 the Italian natural philosopher Galileo Galilei learned of the newly invented spyglass, built improved versions reaching roughly twenty-fold magnification, and turned them on the night sky.
On 7 January 1610 he observed four points of light near Jupiter and soon realised they were moons orbiting the planet. He published his findings rapidly in Sidereus Nuncius (Starry Messenger) on 13 March 1610, the first scientific work based on telescopic observation. The slim treatise reported a rugged, cratered Moon rather than a perfect celestial sphere, vast numbers of stars invisible to the naked eye in the Milky Way, and the four satellites of Jupiter, which he diplomatically named the Medicean Stars after his patrons. The Jovian moons were decisive: they showed that Earth was not the sole centre of motion in the universe, undermining a core objection to heliocentrism. Galileo's telescopic discoveries, soon extended to the phases of Venus and sunspots, brought the Copernican debate out of mathematical abstraction and into direct observation, making him Europe's most celebrated and most controversial natural philosopher.
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Empires active in March 1610
- Ottoman Empire1299 CE – 1922 CE
- Solomonic dynasty1270 CE – 1974 CE
- Mughal Empire1526 CE – 1857 CE
- Portuguese Empire1415 CE – 1999 CE
- Ming Dynasty1368 CE – 1644 CE
- Spanish Empire1492 CE – 1976 CE
Related science, technology & invention events
- Copernicus publishes De revolutionibus and the heliocentric universe1543
- Newton's Principia and universal gravitation1687
- Kepler's laws of planetary motion1609
- William Harvey demonstrates the circulation of the blood1628
- Founding of the Royal Society of London28 November 1660 (chartered 1662)
- Watt patents the rotative steam engine1781
Also relevant
Further reading
The wider story
A Little History of Science
Warm, jargon-free tour of discovery from Babylonian stargazers to the genome.
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