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Updated: May 22, 2025
After Sir William Herschel discovered Uranus, in 1781, it was found that astronomers had observed it on many previous occasions, mistaking it for a fixed star of the sixth or seventh magnitude. Altogether, nineteen observations of Uranus's position, from the time of Flamsteed, in 1690, had been recorded. In 1790 Delambre, using all these observations, prepared tables for computing its position.
Considering the enormous circumference of Uranus's orbit, and his comparatively small mass, we may conclude that the ring from which he resulted was a comparatively slender, and therefore a hoop-shaped one: especially as the nebulous mass must have been at that time less oblate than afterwards.
But he did much more than this: his improvements in the construction of telescopes, and his devotion to astronomy in many other ways, would have caused him to be remembered without anything else. Of Uranus's satellites one, the nearest, goes round in about two and a half days, and the one that is furthest away takes about thirteen and a half days, so both have a shorter period than our moon.
But, since the publication of the Principia, in 1687, there is probably no analytical success which has raised among astronomers such a feeling of admiration and gratitude as when Adams and Le Verrier showed the inequalities in Uranus's motion to mean that an unknown planet was in a certain place in the heavens, where it was found.
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