Johann Franz Encke (; 23 September 179126 August 1865) was a German
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 ...
. Among his activities, he worked on the calculation of the periods of comets and asteroids, measured the distance from the Earth to the Sun, and made observations of the planet Saturn.
Biography
Encke was born in
Hamburg
(male), (female) en, Hamburger(s),
Hamburgian(s)
, timezone1 = Central (CET)
, utc_offset1 = +1
, timezone1_DST = Central (CEST)
, utc_offset1_DST = +2
, postal ...
, where his father was the Pastor at
St. James' Church, Hamburg
St. James' Church (german: Hauptkirche St. Jacobi) is one of the five principal churches (''Hauptkirchen'') of Hamburg. In 1529, it became a Lutheran church. It is located directly in the city centre, has a 125 m tall tower and features a famous or ...
. He was the youngest of eight children, and at the time his father died, when he was four years old, the family was in straitened circumstances. Thanks to the financial assistance of a teacher, he was able to be educated at the
Gelehrtenschule des Johanneums
The ''Gelehrtenschule des Johanneums'' ( ''Academic School of the Johanneum'', short: Johanneum) is a Gymnasium (or Grammar School ) in Hamburg, Germany. It is Hamburg's oldest school and was founded in 1529 by Johannes Bugenhagen. The school's f ...
. He studied
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
and
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 ...
from 1811 at the
University of Göttingen
The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...
under
Carl Friedrich Gauss
Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...
, but he enlisted in the
Hanseatic Legion
The Hanseatic Legion was a military unit, first formed of a group of citizens from Hamburg. They had met in 1813 on the instigation of General Friedrich Karl von Tettenborn, in order to fight in the War of the Sixth Coalition. This association o ...
for the campaign of 1813–1814, serving as a sergeant in the artillery of the
Prussian army
The Royal Prussian Army (1701–1919, german: Königlich Preußische Armee) served as the army of the Kingdom of Prussia. It became vital to the development of Brandenburg-Prussia as a European power.
The Prussian Army had its roots in the co ...
, in Holstein and Mecklenburg. In 1814 he resumed his studies at the University, but after
Napoleon
Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...
's escape from Elba he returned to the military, serving until 1815 by which time he had become a lieutenant.
Having returned to Göttingen in 1816, he was at once appointed by
Bernhardt von Lindenau
Baron Bernhard August von Lindenau (11 June 1779 – 21 May 1854) was a German lawyer, astronomer, politician, and art collector.
Lindenau was born in Altenburg, the son of Johann August Lindenau, a regional administrator (''Landschaftsdirektor)' ...
as his assistant in the
observatory of Seeberg near
Gotha
Gotha () is the fifth-largest city in Thuringia, Germany, west of Erfurt and east of Eisenach with a population of 44,000. The city is the capital of the district of Gotha and was also a residence of the Ernestine Wettins from 1640 until the ...
(he had become acquainted with von Lindenau during his military service). There he completed his investigation of the
comet of 1680
C/1680 V1, also called the Great Comet of 1680, Kirch's Comet, and Newton's Comet, was the first comet discovered by telescope. It was discovered by Gottfried Kirch and was one of the brightest comets of the seventeenth century.
Overview
The co ...
, for which the
Cotta prize was awarded to him in 1817 by judges Gauss and
Olbers. He correctly assigned a period of 71 years to the comet of 1812, now known as ''
12P/Pons-Brooks''.
Following a suggestion by
Jean-Louis Pons
Jean-Louis Pons (24 December 176114 October 1831) was a French astronomer. Despite humble beginnings and being self-taught, he went on to become the greatest visual comet discoverer of all time: between 1801 and 1827 Pons discovered thirty-seven ...
, who suspected one of the three comets discovered in 1818 to be the same one already discovered by him in 1805, Encke began to calculate the
orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...
of this comet. At this time, all the known comets had an
orbital period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...
of seventy years and more, with an
aphelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ellip ...
far beyond the orbit 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 ...
. The most famous comet of this family was
Comet Halley
Halley's Comet or Comet Halley, officially designated 1P/Halley, is a List of periodic comets, short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye fr ...
with its period of seventy-six years. Therefore the orbit of the comet discovered by Pons was a sensation, because his orbit was found to have a period of 3.3 years, so that the aphelion had to be within the orbit of
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
. Encke predicted its return for 1822; this return was observable only from the southern hemisphere and was seen by
Carl Ludwig Christian Rümker
Carl Ludwig Christian Rümker (28 May 1788 – 21 December 1862) was a German astronomer.
Early life (1788-1821)
Rümker was born in Burg Stargard, in Mecklenburg, Germany, the son of J. F. Rümker, a court-councillor. He showed an aptitude for m ...
in Australia. The comet was also identified with the one seen by
Pierre Méchain
Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets.
Life
Pierre Méchain was born i ...
in 1786 and by
Caroline Herschel
Caroline Lucretia Herschel (; 16 March 1750 – 9 January 1848) was a German born British astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigolle ...
in 1795.
Encke sent his calculations as a note to Gauss, Olbers, and
Bessel. His former mathematics professor published this note and Encke became famous as the discoverer of the short periodic comets. The first object of this family, the
Encke comet, was named after him and so it is one of the few comets not named after the discoverer, but after the one who calculated the orbit. Later this comet was identified as the origin of the
Taurids
The Taurids are an annual meteor shower, associated with the comet Encke. The Taurids are actually two separate showers, with a Southern and a Northern component. The Southern Taurids originated from Comet Encke, while the Northern Taurids or ...
meteor shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extre ...
s.
The importance of the predicted return based on the calculation by Encke was rewarded by the
Royal Astronomical Society
(Whatever shines should be observed)
, predecessor =
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in London by presenting their
Gold Medal
A gold medal is a medal awarded for highest achievement in a non-military field. Its name derives from the use of at least a fraction of gold in form of plating or alloying in its manufacture.
Since the eighteenth century, gold medals have bee ...
to him in 1824. In this year Encke married
Amalie Becker
Amalie may refer to:
People
* Amalie (given name), a female given name, derived from Amalia
Places
* Charlotte Amalie, U.S. Virgin Islands, capital of the territory
* Amalie Arena, a hockey stadium in Tampa, Florida
Businesses
* Amalie Oil Com ...
(1787–1879), daughter of author, bookseller and publisher
Rudolph Zacharias Becker, the publisher of works from the Seeberg Observatory. They had three sons and two daughters. In 1825 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 ...
.
Eight masterly treatises on the comet's movements were published by him in the ''Berliner Abhandlungen'' (1829–1859). From a fresh discussion of the
transits of Venus
frameless, upright=0.5
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transi ...
in 1761 and 1769 he deduced a solar
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 8.57
arcsecond
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
. This and the corresponding distance to the sun were long accepted as authoritative.
His results were published in two separate tracts, entitled ''Die Entfernung der Sonne'' (The distance to the sun, 1822–1824).
In 1822 he became director of the
Seeberg
Seeberg is a municipality in the Oberaargau administrative district in the canton of Bern in Switzerland. The lake Burgäschisee is located on the border with Aeschi. On 1 January 2016 the former municipality of Hermiswil merged into Seebe ...
observatory, and in 1825 was promoted to a corresponding position at
Berlin
Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...
, where
a new observatory, built under his superintendence and with the support of
Alexander von Humboldt
Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, p ...
and King
Frederick William III of Prussia
Frederick William III (german: Friedrich Wilhelm III.; 3 August 1770 – 7 June 1840) was King of Prussia from 16 November 1797 until his death in 1840. He was concurrently Elector of Brandenburg in the Holy Roman Empire until 6 August 1806, wh ...
, was inaugurated in 1835.
Mostly on the recommendation of Bessel, Encke became director of the new observatory and secretary of the
Academy of Sciences
An academy of sciences is a type of learned society or academy (as special scientific institution) dedicated to sciences that may or may not be state funded. Some state funded academies are tuned into national or royal (in case of the Unite ...
.
He directed the preparation of the star maps of the Academy (1830–1859); beginning in 1830, he edited and greatly improved the ''Astronomisches Jahrbuch''; and he issued four volumes of the ''Astronomische Beobachtungen auf der Sternwarte zu Berlin'' (Observations of the Berlin observatory, 1840–1857).
Thereafter Encke was involved in the discovery and orbital parameter determination of other short periodic comets and
asteroids
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.
...
.
In 1837, Encke described a broad variation in the brightness of the
A Ring
The rings of Saturn are the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirel ...
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 ...
. The
Encke Gap
The rings of Saturn are the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirel ...
was later named in honour of his observations of Saturn's rings.
In 1844, Encke became professor of astronomy at the
University of Berlin
Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...
. Much labour was bestowed by him upon facilitating the computation of the movements of the asteroids. With this end in view he expounded to the Berlin Academy in 1849 a mode of determining an
elliptic orbit
In astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0. In a stricter sense, it ...
from three observations, and communicated to that body in 1851 a new method of calculating planetary perturbations by means of rectangular coordinates (republished in W. Ostwald's ''Klassiker der exacten Wissenschaften'', No. 141, 1903).
Encke visited England in 1840. He was elected a foreign member of the
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special ...
in 1836, a member to the
American Philosophical Society
The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...
in 1839,
and a Foreign Honorary Member of the
American Academy of Arts and Sciences
The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...
in 1849.
Incipient brain-disease compelled him to withdraw from official life in November 1863.
He still was director of the Berlin observatory until his death on 26 August 1865 in
Spandau
Spandau () is the westernmost of the 12 boroughs () of Berlin, situated at the confluence of the Havel and Spree rivers and extending along the western bank of the Havel. It is the smallest borough by population, but the fourth largest by land ...
. His successor was
Wilhelm Julius Foerster
Wilhelm Julius Foerster (16 December 1832 – 18 January 1921) was a German astronomer. His name can also be written Förster, but is usually written "Foerster" even in most German sources where 'ö' is otherwise used in the text.
Biography
A ...
.
He contributed extensively to the periodical literature of astronomy.
Encke's grave is preserved at a cemetery in the
Kreuzberg
Kreuzberg () is a district of Berlin, Germany. It is part of the Friedrichshain-Kreuzberg borough located south of Mitte. During the Cold War era, it was one of the poorest areas of West Berlin, but since German reunification in 1990 it ha ...
section of Berlin, the ''Friedhof II der Jerusalems- und Neuen Kirchengemeinde'' (Cemetery No. II of the congregations of
Jerusalem's Church
Jerusalem Church (german: Jerusalem(s)kirche, Jerusalemer Kirche) is one of the churches of the Evangelical Congregation in the Friedrichstadt (under this name since 2001), a member of the Protestant umbrella organisation Evangelical Church of ...
and
New Church) (entrance: opposite to 58–60, Zossener Str.; 61, Baruther Str. only for vehicles of the cemetery). His grave is close to that of the mathematician
Carl Gustav Jacob Jacobi
Carl Gustav Jacob Jacobi (; ; 10 December 1804 – 18 February 1851) was a German mathematician who made fundamental contributions to elliptic functions, dynamics, differential equations, determinants, and number theory. His name is occasiona ...
.
Honors
*Twice, in 1824 and 1830, the recipient of 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 ...
.
*The crater
Encke
Encke may refer to:
*Johann Franz Encke (1791–1865), a nineteenth-century German astronomer
**Encke (crater), a lunar crater
**Encke Division, a dark gap in the rings of Saturn
**Comet Encke, a short-period comet
***Encke (horse) (2009–2014), ...
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 ...
is named after him.
*
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.
...
9134 Encke is named in his honour.
*The
Encke gap
The rings of Saturn are the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirel ...
of Saturn's rings is named after him.
*
Comet Encke
Comet Encke , or Encke's Comet (official designation: 2P/Encke), is a periodic comet that completes an orbit of the Sun once every 3.3 years. (This is the shortest period of a reasonably bright comet; the faint main-belt comet 311P/PanSTARRS has ...
is named after him for his calculation of its orbit.
Notes
References
*
External links
Obituary of "John Francis Encke"
{{DEFAULTSORT:Encke, Johann Franz
1791 births
1865 deaths
Scientists from Hamburg
19th-century German astronomers
Prussian Army personnel of the Napoleonic Wars
Recipients of the Gold Medal of the Royal Astronomical Society
University of Göttingen alumni
Humboldt University of Berlin faculty
Royal Medal winners
Members of the Royal Swedish Academy of Sciences
Fellows of the American Academy of Arts and Sciences
Fellows of the Royal Society
Honorary members of the Saint Petersburg Academy of Sciences
Recipients of the Pour le Mérite (civil class)
People educated at the Gelehrtenschule des Johanneums
Recipients of the Lalande Prize