Uranus
John Flamsteed records the earliest definite observation of Uranus
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Original prompt & settings (JSON) ↗The future planet entered astronomy as an innocuous catalogue entry: 34 Tauri.
13 December 1690: a sixth-magnitude object in Taurus
On 13 December 1690, at the Royal Observatory in Greenwich, Astronomer Royal John Flamsteed observed a faint object in Taurus. It was Uranus.
Flamsteed was systematically measuring and cataloguing the positions of apparently fixed stars for the observatory's star-mapping and navigation work. He recorded this one at sixth magnitude and treated it as an ordinary star.
The 13 December date is the contemporary English Julian one; modern astronomical tables commonly normalize it to 23 December 1690.
Filed as 34 Tauri
The object entered Flamsteed's catalogue as 34 Tauri — a star designation, not a planet. No new planet was announced in 1690.
He looked at the same wandering object again in 1712 and 1715 without recognizing that his 'star' had moved. At least six Flamsteed pre-discovery observations are known, spread across those three years.
The position later astronomers came back for
After Uranus was recognized as a planet, Johann Elert Bode went through older catalogues and argued that Flamsteed's 34 Tauri was the same body. The 1690 measurement became the earliest definite pre-discovery position of Uranus.
A scholarly proposal identifies a position inherited from Hipparchus's catalogue in 128 BCE as Uranus. Because that identification remains inferential, Flamsteed's is best described as the earliest definite recorded observation rather than the first human sighting.
Sources
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What the sources leave uncertain
- The listed 13 December date is the contemporary English Julian-calendar date. Modern astronomical tables commonly normalize it to 23 December 1690 Gregorian.
- A scholarly proposal identifies a position inherited from Hipparchus’s catalogue in 128 BCE as Uranus. Because that identification remains inferential, Flamsteed’s is best described as the earliest definite recorded observation, not necessarily the first human sighting.