Thomas Henderson

FRSE 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 ...

FRS

FRAS FRAS may refer to: * Fellow of the Royal Astronomical Society, post-nominal letters * Fellow of the Royal Asiatic Society of Great Britain and Ireland Fellows of the Royal Asiatic Society of Great Britain and Ireland are individuals who have bee ...

(28 December 1798 – 23 November 1844) was a Scottish astronomer and mathematician noted for being the first person to measure the distance to Alpha Centauri, the major component of the nearest stellar system to Earth, the first to determine the

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

of a fixed star, and for being the first

Astronomer Royal for Scotland Astronomer Royal for Scotland was the title of the director of the Royal Observatory, Edinburgh until 1995. It has since been an honorary title. Astronomers Royal for Scotland See also * Edinburgh Astronomical Institution * City Observatory * R ...

Early life

Born in

Dundee Dundee (; sco, Dundee; gd, Dùn Dè or ) is Scotland's fourth-largest city and the 51st-most-populous built-up area in the United Kingdom. The mid-year population estimate for 2016 was , giving Dundee a population density of 2,478/km2 or ...

, he was educated at the

High School of Dundee The High School of Dundee is an independent, co-educational, day school in Dundee, Scotland, which provides nursery, primary and secondary education to just over one thousand pupils. Its foundation has been dated to 1239, and it is the only priv ...

, after which he trained as a lawyer, working his way up through the profession as an assistant to a variety of nobles. However, his major hobbies were astronomy and mathematics, and after coming up with a new method for using lunar

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

to measure

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

he came to the attention of Thomas Young, superintendent of the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

's "Nautical Almanac". Young helped the young Henderson enter the larger world of astronomical science, and on his death a posthumous letter recommended to the Admiralty that Henderson take his place.

Career

Africa

Henderson was passed over for that position, but the recommendation was enough to get him a position at the Royal Observatory at the

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. There he made a considerable number of stellar observations between April 1832 and May 1833, including those for which he is remembered today. It was pointed out to him by

Manuel John Johnson Manuel John Johnson, FRS (23 May 1805 – 28 February 1859) was a British astronomer. He was born in Macao, China, the son of John William Roberts of the East India Company and was educated at Mr Styles' Classical Academy in Thames Ditton and at ...

of the East India Company's observatory on

Saint Helena Saint Helena () is a British overseas territory located in the South Atlantic Ocean. It is a remote volcanic tropical island west of the coast of south-western Africa, and east of Rio de Janeiro in South America. It is one of three constitu ...

that the bright southern star Alpha Centauri had a large

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

, and Henderson concluded that it might be relatively close. The 1830s version of the "space race" was to be the first person to measure the distance to a star using

, a task which is easier the closer the star. Henderson was thus in a good position to be this person. After retiring back to the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

due to bad health, he began analysing his measurements and eventually came to the conclusion that Alpha Centauri was just slightly less than one

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

away, 3.25

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s. This figure is reasonably accurate, being 25.6% too small. Henderson did not immediately publish his results, however (there had been previous, discredited attempts to claim a measurement of stellar parallax), and eventually he was beaten to the punch by

Friedrich Wilhelm Bessel Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method ...

, who published a parallax of 10.3 light years (9.6% too small) for

61 Cygni 61 Cygni is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen ...

in 1838. Henderson published his results in 1839, but was relegated to second place because of his lack of confidence. He later published confirming observations by

Thomas Maclear Sir Thomas Maclear (17 March 1794 – 14 July 1879) was an Irish-born South African astronomer who became Her Majesty's astronomer at the Cape of Good Hope. Life He was born in Newtownstewart, County Tyrone, Ireland, the eldest son of Rev Jam ...

. Alpha Centauri remained the nearest known star until the discovery of

Proxima Centauri Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

in 1915 by Robert T. A. Innes.

Scotland

Thomas Henderson memorial on Calton Hill

In the meantime, his measurement work at the Cape had led him to be appointed the first

in 1834. The vacant chair of astronomy at the

University of Edinburgh The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 15 ...

was given to him on the advice of Prime Minister

Lord Melbourne William Lamb, 2nd Viscount Melbourne, (15 March 177924 November 1848), in some sources called Henry William Lamb, was a British Whig politician who served as Home Secretary (1830–1834) and Prime Minister (1834 and 1835–1841). His first pre ...

. From 1834 he worked at the

City Observatory The City Observatory was an astronomical observatory on Calton Hill in Edinburgh, Scotland. It is also known as the Calton Hill Observatory. The site is enclosed by a boundary wall with a monument to John Playfair, president of the Edinburg ...

(then called the Calton Hill Observatory) in Edinburgh until his death.Encyclopædia Britannica online
Retrieved 20 March 2013. In April, 1840 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 ...

. Henderson became a member or fellow of several distinguished societies, including the

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

(1832) and the

Royal Society of Edinburgh The Royal Society of Edinburgh is Scotland's national academy of science and letters. It is a registered charity that operates on a wholly independent and non-partisan basis and provides public benefit throughout Scotland. It was established i ...

(1834).

Personal life and death

The grave of Alexander James Adie, Greyfriars Kirkyard

He married

Alexander Adie Alexander James Adie FRSE MWS (1775, Edinburgh – 4 December 1858, Edinburgh) was a Scottish maker of medical instruments, optician and meteorologist. He was the inventor of the sympiesometer, patented in 1818. Life He was born the son of Jo ...

's daughter Janet Mary Adie (1808–1842) in 1836 and had one daughter, Janet Mary Jane Henderson (1842–1893) who is buried in the

Grange Cemetery The Grange (originally St Giles' Grange) is an affluent suburb of Edinburgh, just south of the city centre, with Morningside and Greenhill to the west, Newington to the east, The Meadows park and Marchmont to the north, and Blackford Hil ...

. He died at home 1 Hillside Crescent in Edinburgh on 23 November 1844 and is buried in

Greyfriars Kirkyard Greyfriars Kirkyard is the graveyard surrounding Greyfriars Kirk in Edinburgh, Scotland. It is located at the southern edge of the Old Town, adjacent to George Heriot's School. Burials have been taking place since the late 16th century, and a num ...

. The grave may be either in the grave of

or in a grave marked by the stone "to his memory". His name is not recorded on the Adie grave; Adie himself died 14 years after Henderson.

Recognition

A blue plaque is installed on his house at 1 Hillside Crescent. It refers to him as "Thomas J. A. Henderson", similar to middle names wrongly added to Wikipedia around 2007. A larger memorial (naming him "Thomas Henderson") is incorporated in the external wall of the

Publications

* *

References

External links

Astronomical Society of Edinburgh - journal 38
* {{DEFAULTSORT:Henderson, Thomas 1798 births 1844 deaths 19th-century Scottish scientists 19th-century British astronomers Scientists from Dundee People educated at the High School of Dundee Academics of the University of Edinburgh

Thomas Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (disambiguation) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Ap ...

Fellows of the Royal Society of Edinburgh Fellows of the Royal Society Fellows of the Royal Astronomical Society Scottish astronomers 19th-century Scottish lawyers 19th-century Scottish mathematicians Burials at Greyfriars Kirkyard South African astronomers