A 24-inch aperture metal mirror reflector telescope, constructed in a private observatory at Starfield, allowed a Liverpool merchant to observe celestial bodies with unprecedented precision. By grinding and polishing his own mirrors and engineering an equatorial mount for superior tracking, the observer managed to secure discoveries that altered the known map of the solar system.
Early Career and Funding
Born in Bolton in 1799, William Lassell attended Rochdale Academy during his formative years. Following the death of his father, he entered a seven-year apprenticeship as a merchant in Liverpool starting in 1814. He ultimately built a significant personal fortune as a beer brewer. This financial independence permitted him to transition from his commercial duties to his primary interest, astronomy. He established an observatory at his residence, Starfield, in the suburb of West Derby.
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Lassell concentrated his technical efforts on reflecting telescopes. He pioneered the use of the equatorial mount, which permitted his instrument to track astronomical objects as the Earth rotated. Using equipment of his own design, he undertook the laborious tasks of grinding and polishing mirror surfaces. In 1854, he moved his operations to a new site at Bradstones, and in 1855, he constructed a larger 48-inch telescope. Seeking superior atmospheric conditions, he relocated the 48-inch instrument to Malta, where he employed Albert Marth as an observing assistant.
Planetary Discoveries
His technological advancements yielded significant empirical results. In 1846, he identified Triton, the largest moon of Neptune, only 17 days after the discovery of the planet itself. He achieved an independent co-discovery of Hyperion, a moon of Saturn, in 1848. By 1851, he had discovered two additional moons, Ariel and Umbriel, orbiting Uranus. These observations confirmed the efficacy of his self-built reflecting instruments.
Professional Recognition and Legacy
Lassell held several professional memberships, including being a Fellow of the Royal Society and a Fellow of the Royal Society of Literature. He received the Gold Medal of the Royal Astronomical Society in 1849 and the Royal Medal from the Royal Society in 1858. Between 1870 and 1872, he served as the President of the Royal Astronomical Society. Upon his death in Maidenhead in 1880, he left a fortune of £80,000. Today, he is commemorated by the crater Lassell on the Moon, a crater on Mars, the asteroid 2636 Lassell, and a planetary ring of Neptune.
Fast facts
- Born: 1799, Bolton
- Died: 1880, Maidenhead
- Primary Occupation: Astronomer and merchant
- Key Discovery: Triton, 1846
- President of the Royal Astronomical Society: 1870-1872
- Gold Medal of the Royal Astronomical Society: 1849
- Royal Medal: 1858
- Honorary LL.D., University of Cambridge: 1874
Questions readers ask
What significant astronomical objects did William Lassell discover?
He discovered Neptune's moon Triton, Saturn's moon Hyperion, and the Uranian moons Ariel and Umbriel.
Why did Lassell move his 48-inch telescope to Malta?
He relocated the instrument to Malta in 1855 to escape the frequently overcast weather conditions of England and gain better observational clarity.
Achievements
- Fellow of the Royal Society of Literature
- Royal Medal — 1858
- Fellow of the Royal Society
- Fields of research: astronomy
