Henrietta Swan Leavitt (; July 4, 1868 – December 12, 1921
) 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 ...
. A graduate of
Radcliffe College
Radcliffe College was a women's liberal arts college in Cambridge, Massachusetts, and functioned as the female coordinate institution for the all-male Harvard College. Considered founded in 1879, it was one of the Seven Sisters colleges and he ...
, she worked at 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 ...
as a "
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
", tasked with examining
photographic plate
Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinn ...
s in order to measure and catalog the brightness of stars. This work led her to discover the relation between the
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
and the period of
Cepheid variable
A Cepheid variable () is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude.
A strong direct relationship between a Cepheid varia ...
s. Leavitt's discovery provided astronomers with the first "
standard candle
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible o ...
" with which to measure the distance to faraway
galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...
.
Before Leavitt discovered the
period-luminosity relation
In astronomy, a period-luminosity relation is a relationship linking the bolometric luminosity, luminosity of pulsating variable stars with their pulsation period.
The best-known relation is the direct proportionality law holding for Classical Ceph ...
ship for Cepheid variables, the only techniques available to astronomers for measuring the distance to a star were based on
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 ...
and
triangulation
In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to the point from known points.
Applications
In surveying
Specifically in surveying, triangulation involves only angle me ...
. Such techniques can only be used for measuring distances up to hundreds of
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. Leavitt's work allowed astronomers to measure distances up to about 20 million light years. As a result of this, it is now known that our own galaxy, the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...
, has a diameter of about 100,000 light years. After Leavitt's death,
Edwin Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology.
Hubble proved that many objects ...
used Leavitt's period-luminosity relation, together with the galactic
spectral shifts first measured by
Vesto Slipher
Vesto Melvin Slipher (; November 11, 1875 – November 8, 1969) was an American astronomer who performed the first measurements of radial velocities for galaxies. He was the first to discover that distant galaxies are redshifted, thus providing t ...
at
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...
, to establish that the universe is expanding (see
Hubble's law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving a ...
).
Biography
Early life and education
Henrietta Swan Leavitt was born in
Lancaster, Massachusetts
Lancaster is a town in Worcester County, Massachusetts, in the United States. Incorporated in 1653, Lancaster is the oldest town in Worcester County. As of the 2020 census, the town population was 8,441.
History
In 1643 Lancaster was first ...
, the daughter of
Congregational church
Congregational churches (also Congregationalist churches or Congregationalism) are Protestant churches in the Calvinist tradition practising congregationalist church governance, in which each congregation independently and autonomously runs its ...
minister George Roswell Leavitt
and his wife Henrietta Swan Kendrick. She was a descendant of Deacon
John Leavitt
Deacon John Leavitt (1608–1691) was a tailor, public officeholder, and founding deacon of Old Ship Church in Hingham, Plymouth County, Massachusetts, the only remaining 17th-century Puritan meeting house in America and the oldest church in con ...
, an English
Puritan
The Puritans were English Protestants in the 16th and 17th centuries who sought to purify the Church of England of Catholic Church, Roman Catholic practices, maintaining that the Church of England had not been fully reformed and should become m ...
tailor, who settled in the
Massachusetts Bay Colony
The Massachusetts Bay Colony (1630–1691), more formally the Colony of Massachusetts Bay, was an English settlement on the east coast of North America around the Massachusetts Bay, the northernmost of the several colonies later reorganized as the ...
in the early 17th century.
(In the early Massachusetts records the family name was spelled "Levett".) Henrietta Leavitt remained deeply religious and committed to her church throughout her life.
Leavitt attended
Oberlin College
Oberlin College is a Private university, private Liberal arts colleges in the United States, liberal arts college and conservatory of music in Oberlin, Ohio. It is the oldest Mixed-sex education, coeducational liberal arts college in the United S ...
before transferring to
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
's Society for the Collegiate Instruction of Women (later
Radcliffe College
Radcliffe College was a women's liberal arts college in Cambridge, Massachusetts, and functioned as the female coordinate institution for the all-male Harvard College. Considered founded in 1879, it was one of the Seven Sisters colleges and he ...
), receiving a bachelor's degree in 1892.
At Oberlin and Harvard, Leavitt studied a broad curriculum that included Latin and classical Greek, fine arts, philosophy, analytic geometry, and calculus.
["1912: Henrietta Leavitt Discovers the Distance Key." Everyday Cosmology. N.p., n.d. Web. October 20, 2014. ] It wasn't until her fourth year of college that Leavitt took a course in astronomy, in which she earned an A−.
Leavitt also began working as one of the
women "computers" at 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 ...
, hired by its director
Edward Charles Pickering
Edward Charles Pickering (July 19, 1846 – February 3, 1919) was an American astronomer and physicist and the older brother of William Henry Pickering. Along with Carl Vogel, Pickering discovered the first spectroscopic binary stars. He wrote ''E ...
to measure and catalog the brightness of stars as they appeared in the observatory's
photographic plate
Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinn ...
collection. (In the early 1900s, women were not allowed to operate telescopes
, but the scientific data were on the photographic plates.)
In 1893, Leavitt obtained credits toward a graduate degree in astronomy for her work at the Harvard College Observatory, but she never completed that degree.
In 1898 she became a member of the Harvard staff. She left the observatory to make two trips to Europe and completed a stint as an art assistant at
Beloit College
Beloit College is a private liberal arts college in Beloit, Wisconsin. Founded in 1846, when Wisconsin was still a territory, it is the state's oldest continuously operated college. It is a member of the Associated Colleges of the Midwest and has ...
in Wisconsin. At this time, she contracted an illness that led to progressive hearing loss.
Astronomical career
![Leavitt henrietta b1](https://upload.wikimedia.org/wikipedia/commons/4/46/Leavitt_henrietta_b1.jpg)
Leavitt returned to the Harvard College Observatory from her travels in 1903. Because Leavitt had independent means, Pickering initially did not have to pay her. Later, she received , an hour for her work,
being paid only per week. She was reportedly "hard-working, serious-minded …, little given to frivolous pursuits and selflessly devoted to her family, her church, and her career".
One of the women that Leavitt worked with at the Harvard Observatory was
Annie Jump Cannon
Annie Jump Cannon (; December 11, 1863 – April 13, 1941) was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification. With Edward C. Pickering, she is credited with the creation of ...
, who shared the experience of being deaf.
Pickering assigned Leavitt to the study of variable stars of the
Small
Small may refer to:
Science and technology
* SMALL, an ALGOL-like programming language
* Small (anatomy), the lumbar region of the back
* ''Small'' (journal), a nano-science publication
* <small>, an HTML element that defines smaller text ...
and
Large Magellanic Cloud
The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the ...
s, as recorded on photographic plates taken with the Bruce Astrograph of the
Boyden Station of the Harvard Observatory in
Arequipa
Arequipa (; Aymara and qu, Ariqipa) is a city and capital of province and the eponymous department of Peru. It is the seat of the Constitutional Court of Peru and often dubbed the "legal capital of Peru". It is the second most populated city ...
,
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = Seal (emblem), National seal
, national_motto = "Fi ...
. She identified 1,777 variable stars. In 1908 she published her results in the ''Annals of the Astronomical Observatory of Harvard College'', noting that the brighter variables had the longer period.
![HSLeavittHSCr13Fig2 1912](https://upload.wikimedia.org/wikipedia/commons/9/97/HSLeavittHSCr13Fig2_1912.jpg)
In another paper published in 1912, Leavitt looked carefully at the relationship between the periods and the brightness of a sample of 25 of the Cepheids variables in the Small Magellanic Cloud. This paper was communicated and signed by Edward Pickering, but the first sentence indicates that it was "prepared by Miss Leavitt".
Leavitt made a graph of magnitude versus logarithm of period and determined that, in her own words,
She then used the simplifying assumption that all of the Cepheids within the Small Magellanic Cloud were at approximately the same distance, so that their
intrinsic brightness could be deduced from their apparent brightness as registered in the photographic plates, up to a scale factor since the distance to the Magellanic Clouds were as yet unknown. She expressed the hope that parallaxes to some Cepheids would be measured, which soon happened,
thereby allowing her period-luminosity scale to be calibrated.
This reasoning allowed Leavitt to establish that the
logarithm
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 o ...
of the
period
Period may refer to:
Common uses
* Era, a length or span of time
* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
is linearly related to the logarithm of the star's average intrinsic optical
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
(which is the amount of power radiated by the star in the
visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' or simply light. A typical human eye wil ...
).
Leavitt also developed, and continued to refine, the Harvard Standard for photographic measurements, a logarithmic scale that orders stars by brightness over 17 magnitudes. She initially analyzed 299 plates from 13 telescopes to construct her scale, which was accepted by the International Committee of Photographic Magnitudes in 1913.
In 1913, Leavitt discovered
T Pyxidis
T Pyxidis (''T Pyx'') is a recurrent nova
and nova remnant in the constellation Pyxis. It is a binary star system and its distance is estimated at about from Earth. It contains a Sun-like star and a white dwarf. Because of their clos ...
, a
recurrent 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 dramat ...
in
Pyxis
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass (contrasting with Circinus, which represents a draftsman's compasses). Pyxis was introduced by Nicolas-Lo ...
, and one of the most frequent recurrent novae in the sky with eruptions observed in 1890, 1902, 1920, 1944, 1967, and 2011.
Leavitt was a member of
Phi Beta Kappa
The Phi Beta Kappa Society () is the oldest academic honor society in the United States, and the most prestigious, due in part to its long history and academic selectivity. Phi Beta Kappa aims to promote and advocate excellence in the liberal a ...
, the
American Association of University Women
The American Association of University Women (AAUW), officially founded in 1881, is a non-profit organization that advances equity for women and girls through advocacy, education, and research. The organization has a nationwide network of 170,000 ...
, the
American Astronomical and Astrophysical Society, the
American Association for the Advancement of Science
The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...
, and an honorary member of the
American Association of Variable Star Observers
The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization, founded in 1911, focused on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers. ...
. In 1921, when
Harlow Shapley
Harlow Shapley (November 2, 1885 – October 20, 1972) was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.
Shapley used Cepheid variable stars to estim ...
took over as director of the observatory, Leavitt was made head of stellar
photometry Photometry can refer to:
* Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision
* Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electro ...
. By the end of that year she had succumbed to cancer and was buried in the Leavitt family plot at Cambridge Cemetery in
Cambridge, Massachusetts
Cambridge ( ) is a city in Middlesex County, Massachusetts, United States. As part of the Boston metropolitan area, the cities population of the 2020 U.S. census was 118,403, making it the fourth most populous city in the state, behind Boston, ...
.
Scientific impact
![Henrietta Swan Leavitt 1921](https://upload.wikimedia.org/wikipedia/commons/9/97/Henrietta_Swan_Leavitt_1921.png)
According to science writer
Jeremy Bernstein
Jeremy Bernstein (born December 31, 1929, in Rochester, New York) is an American theoretical physicist and popular science writer.
Early life
Bernstein's parents, Philip S. Bernstein, a Reform rabbi, and Sophie Rubin Bernstein named him after th ...
, "variable stars had been of interest for years, but when she was studying those plates, I doubt Pickering thought she would make a significant discovery—one that would eventually change astronomy." The period–luminosity relationship for Cepheids, now known as "Leavitt's law", made the stars the first "
standard candle
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible o ...
" in astronomy, allowing scientists to compute the
distances
Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...
to stars too remote for
stellar parallax
Stellar parallax is the apparent shift of position of any nearby star (or other object) against the background of distant objects, and a basis for determining (through trigonometry) the distance of the object. Created by the different orbital p ...
observations to be useful. One year after Leavitt reported her results,
Ejnar Hertzsprung
Ejnar Hertzsprung (; Copenhagen, 8 October 1873 – 21 October 1967, Roskilde) was a Danish chemist and astronomer.
Career
Hertzsprung was born in Frederiksberg, Denmark, the son of Severin and Henriette. He studied chemical engineering at Cop ...
determined the distance of several Cepheids in the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...
; with this calibration, the distance to any Cepheid could be accurately determined.
Cepheids were soon detected in other galaxies, such as
Andromeda (notably by Edwin Hubble in 1923–24), and they became an important part of the evidence that "spiral nebulae" are independent galaxies located far outside of our own
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...
. Thus, Leavitt's discovery would forever change our picture of the universe, as it prompted
Harlow Shapley
Harlow Shapley (November 2, 1885 – October 20, 1972) was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.
Shapley used Cepheid variable stars to estim ...
to move our Sun from the center of the galaxy in the "
Great Debate" and
Edwin Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology.
Hubble proved that many objects ...
to move our galaxy from the center of the universe.
Leavitt's discovery of a way to accurately measure distances on an inter-galactic scale, paved the way for modern astronomy's understanding of the structure and scale of the universe.
The accomplishments of
Edwin Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology.
Hubble proved that many objects ...
, the American astronomer who established that the universe is expanding, also were made possible by Leavitt's groundbreaking research. Hubble often said that Leavitt deserved the Nobel Prize for her work. Mathematician
Gösta Mittag-Leffler, a member of the
Swedish Academy of Sciences, tried to nominate her for that prize in 1925, only to learn that she had died of cancer three years earlier.
(The Nobel Prize is not awarded posthumously.)
Cepheid variables allow astronomers to measure distances up to about 60 million light years. Even greater distances can now be measured by using the theoretical maximum mass of
white dwarf
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes fro ...
s calculated by
Subrahmanyan Chandrasekhar.
Illness and death
![Henrietta Swan Leavitt marker](https://upload.wikimedia.org/wikipedia/commons/f/f0/Henrietta_Swan_Leavitt_marker.agr.jpg)
Leavitt's scientific work at Harvard was frequently interrupted by illness and family obligations. Her early death at the age of 53 from stomach cancer was seen as a tragedy by her colleagues for reasons that went beyond her scientific achievements. Her colleague
Solon I. Bailey
Solon Irving Bailey (December 29, 1854 – June 5, 1931) was an American astronomer and discoverer of the main-belt asteroid 504 Cora, on June 30, 1902.
Bailey joined the staff of Harvard College Observatory in 1887. He received an M.A. from th ...
wrote in her obituary that "she had the happy, joyful, faculty of appreciating all that was worthy and lovable in others, and was possessed of a nature so full of sunshine that, to her, all of life became beautiful and full of meaning."
"Sitting at the top of a gentle hill," writes George Johnson in his biography of Leavitt, "the spot is marked by a tall hexagonal monument, on top of which sits a globe cradled on a draped marble pedestal. Her uncle
Erasmus Darwin Leavitt and his family also are buried there, along with other Leavitts." A plaque memorializing Henrietta and her two siblings, Mira and Roswell, is mounted on one side of the monument. Nearby are the graves of
Henry
Henry may refer to:
People
*Henry (given name)
* Henry (surname)
* Henry Lau, Canadian singer and musician who performs under the mononym Henry
Royalty
* Portuguese royalty
** King-Cardinal Henry, King of Portugal
** Henry, Count of Portugal, ...
and
William James
William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States.
James is considered to be a leading thinker of the lat ...
.
Posthumous honors
* 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.
...
5383 Leavitt and the crater
Leavitt 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 ...
are named after her to honor deaf men and women who have worked as astronomers.
* One of the
ASAS-SN
The All Sky Automated Survey for SuperNovae (ASAS-SN) is an automated program to search for new supernovae and other astronomical transients, headed by astronomers from the Ohio State University,
including Christopher Kochanek and Krzysztof Stanek. ...
telescopes, located in the
McDonald Observatory
McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional facil ...
in Texas, is named in her honor.
Books, plays and other media
Lauren Gunderson
Lauren Gunderson (born February 5, 1982) is an American playwright, screenwriter, and short story author, born in Atlanta. She lives in San Francisco, where she teaches playwriting. Gunderson was recognized by ''American Theatre'' magazine as A ...
wrote a play, ''Silent Sky'', which followed Leavitt's journey from her acceptance at Harvard to her death.
George Johnson wrote a biography, ''Miss Leavitt's Stars'', which showcases the triumphs of women's progress in science through the story of Leavitt.
Robert Burleigh wrote the biography ''Look Up!: Henrietta Leavitt, Pioneering Woman Astronomer'' for a younger audience. It is written for four- to eight-year-olds.
Theo Strassell wrote a play, "The Troubling Things We Do," an absurdist piece that details the life of Henrietta Leavitt, among other scientists from her era.
Dava Sobel's book ''The Glass Universe'' chronicles the work of the women analyzing images taken of the stars at the Havard College Observatory.
The BBC included Leavitt in their ''Missed Genius'' series designed to celebrate individuals from diverse backgrounds who have had a profound effect on our world.
See also
*
List of female scientists
This is a ''historical'' list, intended to deal with the time period where it is believed that women working in science were rare. For this reason, this list ends with the 20th century.
Antiquity
* Gargi Vachaknavi (7th century BCE), Indian p ...
*
List of deaf people
*
Women in science
The presence of women in science spans the earliest times of the history of science wherein they have made significant contributions. Historians with an interest in gender and science have researched the scientific endeavors and accomplishments ...
*
Timeline of women in science
This is a timeline of women in science, spanning from ancient history up to the 21st century. While the timeline primarily focuses on women involved with natural sciences such as astronomy, biology, chemistry and physics, it also includes women f ...
*
Human computer
The term "computer", in use from the early 17th century (the first known written reference dates from 1613), meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available. Ala ...
*
Cepheids
A Cepheid variable () is a type of star that Instability strip, pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable frequency, period and amplitude.
A strong direct period-l ...
References
Further reading
*
Sources
*
*
*
External links
Women in Astronomy Bibliographyfrom the
Astronomical Society of the Pacific
Periods of 25 Variable Stars in the Small Magellanic Cloud.Edward C. Pickering, March 3, 1912; credits Leavitt.
Henrietta Swan Leavitt: a Star of the Brightest MagnitudeACS/Women Chemists Committee's biography with several links
Henrietta Swan Leavitt Tim Hunter (astronomer)
Timothy B. Hunter, better known as Tim Hunter, is an American radiologist and amateur astronomer, who was the president of the International Dark-Sky Association.
Education and profession
Hunter received his M.D. degree from Northwestern Univer ...
, The Grasslands Observatory
Henrietta Swan Leavitt's genealogy*
{{DEFAULTSORT:Leavitt, Henrietta Swan
1868 births
1921 deaths
Astrometry
American women astronomers
Cepheid variables
History of women in the United States
Harvard Computers
Harvard University staff
Radcliffe College alumni
People from Lancaster, Massachusetts
Leavitt family
American Congregationalists
Deaths from cancer in Massachusetts
19th-century American astronomers
20th-century American astronomers
19th-century American women scientists
20th-century American women scientists
Deaf people from the United States
Oberlin College alumni
Scientists with disabilities