Seth Carlo Chandler, Jr. (September 16, 1846 – December 31, 1913) was an American

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 ...

geodesist Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

, and

actuary An actuary is a business professional who deals with the measurement and management of risk and uncertainty. The name of the corresponding field is actuarial science. These risks can affect both sides of the balance sheet and require asset man ...

. He was born in

Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

to Seth Carlo and Mary (née Cheever) Chandler. During his last year in high school he performed mathematical computations for

Benjamin Peirce Benjamin Peirce (; April 4, 1809 – October 6, 1880) was an American mathematician who taught at Harvard University for approximately 50 years. He made contributions to celestial mechanics, statistics, number theory, algebra, and the philoso ...

, of the

Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United St ...

. After graduating, he became the assistant of Benjamin A. Gould. Gould was director of the

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 ...

Department of the

U.S. Coast Survey The United States Coast and Geodetic Survey (abbreviated USC&GS), known from 1807 to 1836 as the Survey of the Coast and from 1836 until 1878 as the United States Coast Survey, was the first scientific agency of the United States Government. It ...

program, a

geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

survey program. When Gould left to become director of the national observatory in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, Chandler also left and became an actuary. However, he continued to work in astronomy as an amateur affiliated with Harvard College Observatory. Chandler is best remembered for his research on what is today known as the

Chandler wobble The Chandler wobble or Chandler variation of latitude is a small deviation in the Earth's axis of rotation relative to the solid earth, which was discovered by and named after American astronomer Seth Carlo Chandler in 1891. It amounts to change o ...

. His research on

polar motion Polar motion of the Earth is the motion of the Earth's rotational axis relative to its crust. This is measured with respect to a reference frame in which the solid Earth is fixed (a so-called ''Earth-centered, Earth-fixed'' or ECEF reference f ...

spanned nearly three decades. Chandler also made contributions to other areas of astronomy, including

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

s. He independently co-discovered the

nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramati ...

T Coronae Borealis T Coronae Borealis (''T CrB''), is a recurring nova in the constellation Corona Borealis. It was first discovered in outburst in 1866 by John Birmingham, although it had been observed earlier as a 10th magnitude star. Description T CrB ...

, improved the estimate of the constant of aberration, and computed the orbital parameters of

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. ...

s and

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

s. Chandler was awarded 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 1896 and the

James Craig Watson Medal 400px, James Craig Watson Medal The James Craig Watson Medal was established by the bequest of James Craig Watson, an astronomer the University of Michigan between 1863 and 1879, and is awarded every 1-4 years by the U.S. National Academy of Scienc ...

in 1894. The crater

Chandler Chandler or The Chandler may refer to: * Chandler (occupation), originally head of the medieval household office responsible for candles, now a person who makes or sells candles * Ship chandler, a dealer in supplies or equipment for ships Arts ...

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.

References

Bibliography

*"Latitude, How American Astronomers Solved the Mystery of Variation" by Bill Carter and Merri Sue Carter, Naval Institute Press, Annapolis, MD., 2002. * {{DEFAULTSORT:Chandler, Seth 1846 births 1913 deaths American astronomers Recipients of the Gold Medal of the Royal Astronomical Society Harvard College Observatory people Recipients of the Lalande Prize The Astronomical Journal editors American geodesists American actuaries