William Lassell - brewer turned astronomer and his discoveries

Oct. 24, 1851 - William Lassell discovered two moons of Uranus, Umbriel and Ariel.

William Lassell was an English merchant and made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy.

He built an observatory at his house "Starfield" in West Derby, a suburb of Liverpool. There he had a 24-inch (610 mm) reflector telescope, for which he pioneered the use of an equatorial mount for easy tracking of objects as the Earth rotates. He ground and polished the mirror himself, using equipment he constructed.

In 1846 Lassell discovered Triton, the largest moon of Neptune, just 17 days after the discovery of Neptune itself by German astronomer Johann Gottfried Galle. In 1848 he independently co-discovered Hyperion, a moon of Saturn. In 1851 he discovered Ariel and Umbriel, two moons of Uranus.

In 1850, Lassell made his first sighting of the dark inner ring of Saturn (called the crepe ring); he spent the entire night verifying the discovery only to find in his morning newspaper an article announcing William Bond’s discovery of the same phenomenon.

Umbriel is a moon of Uranus and consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle

Ariel is the fourth-largest of the 27 known moons of Uranus

The crater Lassell on the Moon, a crater on Mars, the asteroid 2636 Lassell and a ring of Neptune are named in his honour. At the University of Liverpool the William Lassell prize is awarded to the student with the highest grades graduating the B.Sc. program in Physics with Astronomy each year.

Sources -

1. Encyclopædia Britannica
2. Journal for the History of Astronomy
3. Wikipedia
4. Pacific Science Center