William Lassell (18 June 1799 – 5 October 1880) was an English merchant and

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

.AN 98(1881) 108
He is remembered for his improvements to the

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

and his ensuing discoveries of four planetary satellites.

Life

William Lassell was born in

Bolton Bolton ( , locally ) is a town in Greater Manchester in England. In the foothills of the West Pennine Moors, Bolton is between Manchester, Blackburn, Wigan, Bury, Greater Manchester, Bury and Salford. It is surrounded by several towns and vill ...

, Lancashire, on 18 June 1799. He received his early education in Bolton and later attended

Rochdale Rochdale ( ) is a town in Greater Manchester, England, and the administrative centre of the Metropolitan Borough of Rochdale. In the United Kingdom 2021 Census, 2021 Census, the town had a population of 111,261, compared to 223,773 for the wid ...

Academy.. After the death of his father, William Lassell was apprenticed to a merchant in Liverpool from 1814 to 1821. He later made his fortune as a beer

brewer Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer, ...

, which afforded him the means to pursue his passion for

astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

. He built an observatory at his house
Starfield
in West Derby, a suburb of

Liverpool Liverpool is a port City status in the United Kingdom, city and metropolitan borough in Merseyside, England. It is situated on the eastern side of the River Mersey, Mersey Estuary, near the Irish Sea, north-west of London. With a population ...

. There he had a aperture metal mirror reflector

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

(aka the "two-foot" 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. The observatory was later (1854) moved further out of Liverpool, t
Bradstones
In 1846, Lassell discovered Triton, the largest

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

, just 17 days after the discovery of Neptune itself by German astronomer Johann Gottfried Galle, using his self-built instrument. In 1848, he independently co-discovered Hyperion, a moon of

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

. In 1851 he discovered Ariel and Umbriel, two moons of

Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...

. In 1855, he built a telescope, which he installed in

Malta Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two ...

because of the observing conditions that were better than in often-overcast England. While in Malta his astronomical observing assistant was

Albert Marth Albert Marth (5 May 1828 – 6 August 1897) was a German astronomer who worked in United Kingdom, Britain and Ireland. Life After studying theology at the University of Berlin, his interest in astronomy and mathematics led him to study astro ...

. On his return to the UK after several years in Malta, he moved to

Maidenhead Maidenhead is a market town in the Royal Borough of Windsor and Maidenhead in the county of Berkshire, England. It lies on the southwestern bank of the River Thames, which at this point forms the border with Buckinghamshire. In the 2021 Census, ...

and operated his telescope in an observatory there. The 48-inch telescope was dismantled and was eventually scrapped. The 24-inch telescope was later moved to

Royal Observatory, Greenwich The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux) is an observatory situated on a hill in Gre ...

in the 1880s, but eventually dismantled. Lassell was a Fellow of the Royal Astronomical Society (FRAS) from 1839, won the Gold Medal of the Royal Astronomical Society in 1849, and served as its president for two years starting in 1870. He was elected a

Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the Fellows of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural science, natural knowledge, incl ...

(FRS) in 1849 and won their Royal Medal in 1858. Lassell was also a

Fellow of the Royal Society of Literature The Royal Society of Literature (RSL) is a learned society founded in 1820 by George IV of the United Kingdom, King George IV to "reward literary merit and excite literary talent". A charity that represents the voice of literature in the UK, the ...

(FRSL). He was furthermore elected an honorary

Fellow of the Royal Society of Edinburgh Fellowship of the Royal Society of Edinburgh (FRSE) is an award granted to individuals that the Royal Society of Edinburgh, Scotland's national academy of science and Literature, letters, judged to be "eminently distinguished in their subject". ...

(HonFRSE) and of the Society of Sciences of Upsala, and received an honorary LL.D. degree from the

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

in 1874. Lassell died in

in 1880 and is buried at St. Luke's Church. Upon his death, he left a fortune of £80,000 (roughly ). His telescope was presented to the Royal Observatory in Greenwich. The crater Lassell on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

, a crater on

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

, the

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

2636 Lassell and a ring of Neptune are named in his honour. At the

University of Liverpool The University of Liverpool (abbreviated UOL) is a Public university, public research university in Liverpool, England. Founded in 1881 as University College Liverpool, Victoria University (United Kingdom), Victoria University, it received Ro ...

the William Lassell prize is awarded to the student with the highest grades graduating the B.Sc. program in Physics with Astronomy each year.

Obituaries

Astronomical Register
18 (1880), p.284 *

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

, 22 (1880), p.565 * The Observatory, 3 (1880), p.587 *

Monthly Notices of the Royal Astronomical Society ''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal in astronomy, astrophysics and related fields. It publishes original research in two formats: papers (of any length) and letters (limited to ...

, 41 (1880), p.188

References

External links

Biography and other topics

{{DEFAULTSORT:Lassel, William 1799 births 1880 deaths People from Bolton 19th-century English astronomers Neptune Uranus Saturn Recipients of the Gold Medal of the Royal Astronomical Society Fellows of the Royal Society Royal Medal winners Discoverers of moons Presidents of the Royal Astronomical Society Fellows of the Royal Society of Literature Members of the Royal Society of Sciences in Uppsala

Life

Obituaries

See also

References

External links