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Herschel, Sir (Frederick) William

discovered uranus telescope motion

[her shl] (1738–1822) German–British astronomer: discovered Uranus, the Sun’s intrinsic motion through space and the true nature of the Milky Way.

Herschel followed his father in becoming a musician in the Hanoverian Guards, entering as an oboist at 14. At 19 he came to England, working as a freelance musician before appointment as an organist in Bath. He was a keen amateur telescope maker and observer. His sister joined him in Bath in 1772.

Herschel’s first important discovery was the planet Uranus in 1781. This achievement, helped by his desire to name it after George III, resulted in his appointment the following year as Court Astronomer. This enabled him to finance the construction of a reflecting telescope 20 feet in length and with an aperture of 20 inches, with which he was to make many further discoveries. In 1787 he found two satellites of Uranus, Titania and Oberon, and soon afterwards two of Saturn, Mimas and Enceladus. In 1783 he discovered the intrinsic motion of the Sun through space by careful analysis of the proper motions of seven bright stars, showing them to converge towards a point. He had a special interest in double stars, cataloguing 800 of them and discovering in 1793 that many were in relative orbital motion. In 1820 he published a catalogue of over 5000 nebulae (a task that his son, John, was to continue in the southern hemisphere). He was the first to recognize the true nature of the Milky Way as a galaxy by counting the number of stars visible in different directions, finding that the greatest number lie in the galactic plane, and the least toward the celestial poles. Investigating the effect of parts of the Sun’s spectrum on a thermometer, he discovered infrared radiation, outside the visible range.

William Herschel in his garden at Datchet with the 20-foot (focus) reflecting telescope made by him and his sister Caroline. He thought it the most satisfactory of all their telescopes, using it to record over 2000 nebulae, star clusters and comets. It was awkward to handle, and Caroline (who positioned it and recorded observations) noted ‘I could give a pretty long list of accidents, which were near proving fatal to my brother as well as myself.’

Herschel, Sir John (Frederick William) [next] [back] Herschel, Caroline (Lucretia)

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