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 their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

.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 large town in Greater Manchester in North West England, formerly a part of Lancashire. A former mill town, Bolton has been a production centre for textiles since Flemish people, Flemish weavers settled in the area i ...

Lancashire Lancashire ( , ; abbreviated Lancs) is the name of a historic county, ceremonial county, and non-metropolitan county in North West England. The boundaries of these three areas differ significantly. The non-metropolitan county of Lancashi ...

. He was educated first in Bolton then at

Rochdale Rochdale ( ) is a large town in Greater Manchester, England, at the foothills of the South Pennines in the dale on the River Roch, northwest of Oldham and northeast of Manchester. It is the administrative centre of the Metropolitan Borough ...

Academy. After the death of his father, he was apprenticed from 1814 to 1821 to a merchant in Liverpool. He then 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 enabled him to indulge his interest in

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

. He built an observatory at his house "Starfield" in

West Derby West Derby ( ) is an affluent suburb of Liverpool, England. It is located East of the city and is also a Liverpool City Council ward. At the 2011 Census, the population was 14,382. History West Derby Mentioned in the ''Domesday Book'', Wes ...

, a suburb of

Liverpool Liverpool is a city and metropolitan borough in Merseyside, England. With a population of in 2019, it is the 10th largest English district by population and its metropolitan area is the fifth largest in the United Kingdom, with a popul ...

. There he had a

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

metal mirror reflector

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

(aka the "two-foot" telescope), for which he pioneered the use of an

equatorial mount An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, the polar axis, parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras. The ...

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, to

Bradstone Bradstone is a village in Devon, England, on the River Tamar. It has a small church and a Tudor hall (now a farm) with an attractive gatehouse. Bradstone Manor Farm is a Grade II listed manor house with a Grade I listed 16th century gatehouse. ...

. In 1846, Lassell discovered

Triton Triton commonly refers to: * Triton (mythology), a Greek god * Triton (moon), a satellite of Neptune Triton may also refer to: Biology * Triton cockatoo, a parrot * Triton (gastropod), a group of sea snails * ''Triton'', a synonym of ''Triturus' ...

, the largest

moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

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

, just 17 days after the discovery of Neptune itself by German astronomer

Johann Gottfried Galle Johann Gottfried Galle (9 June 1812 – 10 July 1910) was a German astronomer from Radis, Germany, at the Berlin Observatory who, on 23 September 1846, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the pl ...

, 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 nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

. In 1851 he discovered

Ariel Ariel may refer to: Film and television *Ariel Award, a Mexican Academy of Film award * ''Ariel'' (film), a 1988 Finnish film by Aki Kaurismäki * ''ARIEL Visual'' and ''ARIEL Deluxe'', 1989 and 1991 anime video series based on the novel series ...

and Umbriel, two moons of

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...

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

Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...

because of the observing conditions that were better than in often-overcast England. 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, on the southwestern bank of the River Thames. It had an estimated population of 70,374 and forms part of the border with southern Bu ...

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 ...

in the 1880s, but eventually dismantled. Lassell was a

Fellow of the Royal Astronomical Society (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NGO ...

(FRAS) from 1839, won the

Gold Medal of the Royal Astronomical Society The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...

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 judges 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 The Royal Medal, also known as The Queen's Medal and The King's Medal (depending on the gender of the monarch at the time of the award), is a silver-gilt medal, of which three are awarded each year by the Royal Society, two for "the most important ...

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 King George IV, to "reward literary merit and excite literary talent". A charity that represents the voice of literature in the UK, the RSL has about 600 Fellows, elec ...

(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 letters, judged to be "eminently distinguished in their subject". This soci ...

(HonFRSE) and of the Society of Sciences of Upsala, and received an honorary

LL.D. Legum Doctor (Latin: “teacher of the laws”) (LL.D.) or, in English, Doctor of Laws, is a doctorate-level academic degree in law or an honorary degree, depending on the jurisdiction. The double “L” in the abbreviation refers to the early ...

degree from the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

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 is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

, a crater on

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

, the

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

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

University of Liverpool , mottoeng = These days of peace foster learning , established = 1881 – University College Liverpool1884 – affiliated to the federal Victoria Universityhttp://www.legislation.gov.uk/ukla/2004/4 University of Manchester Act 200 ...

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

References

External links

Biography and other topics
{{DEFAULTSORT:Lassel, William 1799 births 1880 deaths People from Bolton 19th-century British 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

See also

References

External links