William McCrea (astronomer)
Encyclopedia
Sir William Hunter McCrea FRS (13 December 1904, Dublin – 25 April 1999) was an English
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

.

Biography

His family moved to Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...

 in 1906 and then Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...

 where he attended Chesterfield Grammar School
Brookfield Community School
Brookfield Community School is a school located on Chatsworth in the west of the town of Chesterfield, Derbyshire in England.-Admissions:Brookfield Community School is a secondary school and a Sports College And A Language College...

. His father was a school master at Netherthorpe Grammar School
Netherthorpe School
Netherthorpe School is a secondary school designated science college status that is based in the town of Staveley in the Chesterfield district of Derbyshire.-History:The school was founded in 1572A quote from an 1857 directory:...

 in Staveley
Staveley, Derbyshire
Staveley is a town within the borough of Chesterfield, in Derbyshire, England. The town is situated alongside the River Rother, adjacent to Eckington to the north, Barlborough to the east, Sutton-cum-Duckmanton civil parish to the south and Brimington to the west.-History:It has traditionally been...

. He went to Trinity College, Cambridge
Trinity College, Cambridge
Trinity College is a constituent college of the University of Cambridge. Trinity has more members than any other college in Cambridge or Oxford, with around 700 undergraduates, 430 graduates, and over 170 Fellows...

 in 1923 where he studied Mathematics, later gaining a PhD
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...

 in 1929 under Ralph H. Fowler
Ralph H. Fowler
Sir Ralph Howard Fowler OBE FRS was a British physicist and astronomer.-Education:Fowler was initially educated at home but then attended Evans' preparatory school at Horris Hill and Winchester College...

. He was later appointed a lecturer of Mathematics at the University of Edinburgh
University of Edinburgh
The University of Edinburgh, founded in 1583, is a public research university located in Edinburgh, the capital of Scotland, and a UNESCO World Heritage Site. The university is deeply embedded in the fabric of the city, with many of the buildings in the historic Old Town belonging to the university...

 in 1929. He also served as reader and assistant professor at Imperial College London
Imperial College London
Imperial College London is a public research university located in London, United Kingdom, specialising in science, engineering, business and medicine...

. In 1936 he became head of the mathematics department at the Queen's University of Belfast
Queen's University of Belfast
Queen's University Belfast is a public research university in Belfast, Northern Ireland. The university's official title, per its charter, is the Queen's University of Belfast. It is often referred to simply as Queen's, or by the abbreviation QUB...

. After serving in the war, he joined the mathematics department at Royal Holloway College
Royal Holloway, University of London
Royal Holloway, University of London is a constituent college of the University of London. The college has three faculties, 18 academic departments, and about 8,000 undergraduate and postgraduate students from over 130 different countries...

 in 1944 (the McCrea Building on Royal Holloway's campus is named after him). In 1965, McCrea created the astronomy centre of the physics department at the University of Sussex
University of Sussex
The University of Sussex is an English public research university situated next to the East Sussex village of Falmer, within the city of Brighton and Hove. The University received its Royal Charter in August 1961....

.

Discoveries

In 1928, he studied Albrecht Unsöld
Albrecht Unsöld
Albrecht Otto Johannes Unsöld was a German astrophysicist known for his contributions to spectroscopic analysis of stellar atmospheres.-Career:...

's hypothesis, and discovered that three quarters of the Sun is made of Hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, and about one quarter is Helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

, with 1% being other elements. Previous to this many people thought the Sun consisted mostly of Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

. After this, people realized most stars consist of Hydrogen.

Awards

McCrea was president of the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...

 from 1961-3 and president of Section A of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...

 from 1965-6. He was knighted in 1985. He won the Gold Medal of the Royal Astronomical Society
Gold Medal of the Royal Astronomical Society
-History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...

 in 1976. McCrea died on April 25, 1999 in Lewes
Lewes
Lewes is the county town of East Sussex, England and historically of all of Sussex. It is a civil parish and is the centre of the Lewes local government district. The settlement has a history as a bridging point and as a market town, and today as a communications hub and tourist-oriented town...

.
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