Henrietta Leavitt
"A straight line can readily be drawn among each of the two series of points corresponding to maxima and minima, thus showing that there is a simple relation between the brightness of the variables and their periods."
Henrietta Swan Leavitt (July 4, 1868 – December 12, 1921) was an American astronomer who discovered the relation between the luminosity and the period of Cepheid variable stars. A graduate of Radcliffe College, Leavitt started working at the Harvard College Observatory as a "computer" in 1893, examining photographic plates in order to measure and catalog the brightness of the stars. Though she received little recognition in her lifetime, it was her discovery that first allowed astronomers to measure the distance between the Earth and faraway galaxies
Early years
Henrietta Swan Leavitt, the daughter of Congregational church minister George Roswell Leavitt and his wife Henrietta Swan, was born in Lancaster, Massachusetts.
She attended Oberlin College and graduated from Radcliffe College, then called the Society for the Collegiate Instruction for Women, with a bachelor's degree in 1892. She studied a broad curriculum including classical Greek, fine arts, philosophy, analytic geometry, and calculus. It wasn't until her fourth year of college that Leavitt took a course in astronomy, in which she earned an A–. She then traveled in America and in Europe, during which time she lost her hearing.
Career
Henrietta Swan Leavitt was one of a number of volunteer women astronomers who were allowed to serve as "computers" at Harvard College Observatory, doing tedious work male scientists wouldn't do, and ultimately making a discovery now known as Leavitt's Law, which allows us to measure the distance to stars.
Achievements
Leavitt’s outstanding achievement was her discovery in 1912 that in a certain class of variable stars, the Cepheid variables, the period of the cycle of fluctuation in brightness is highly regular and is determined by the actual luminosity of the star. The subsequent calibration of the period-luminosity curve allowed American astronomers Edwin Hubble, Harlow Shapley, and others to determine the distances of many Cepheid stars and consequently of the star clusters and galaxies in which they were observed. The most dramatic application was Hubble’s use in 1924 of a Cepheid variable to determine the distance to the great nebula in Andromeda, which was the first distance measurement for a galaxy outside the Milky Way. Although it was later discovered that there are actually two different types of Cepheid variable, the same method can still be applied separately to each type.
Awards and honors
During her lifetime she received neither plaudits, nor acclaim, nor even serious recognition from her peers. Even today, she is little known, with not even a plaque hanging to commemorate her name at the Harvard College Observatory where she worked, and where her far-reaching breakthrough took place.
Leavitt’s discovery brought fame and glory to many of her peers: without it, Edwin Hubble might have never been able to show that the spiral nebula Andromeda was not located at the edge of our galaxy, as had been previously thought, but almost a million light years away. Nor might the Danish astronomer Ejnar Hertzsprung been able to measure the parallax of many of the nearby Cepheid variables; even though while using Leavitt’s discovery to his advantage, a slip of his pen is alleged to have caused him to underestimate the stars’ distance by a factor of 10.
Some of those closer to the heart of Leavitt’s discovery profited too – not least Edward Pickering, who as director of the Harvard College Observatory publushed her findings in his own name, effectively taking most of the credit. The statement, which appeared in a Harvard Circular in 1912, referred to Leavitt only as the person who had ‘prepared’ it. Pickering’s successor at the observatory, Harlow Shapley, gained fame six years later when he built on Leavitt’s discovery of the period-luminosity relation to redefine our knowledge of the Milky Way. Without Leavitt’s findings his discovery would have not been possible, was once again barely mentioned.
Little is known of Henrietta Leavitt’s personal feelings about the way she had been overstepped. Hers was a shy and somewhat unassuming personality, and women at that time, even highly educated and brilliantly talented women who in a fairer world would have been respected as equals by their male peers, were all too often resigned to taking a lesser role, and were often just quietly grateful to be given any sort of role at all. A possible insight into Henrietta’s private thoughts is offered by her reply to a census taker who, in January 1920, the year before her death, asked her to state her occupation,There might have been a hint of defiant pride in her answer, ‘Astronomer’. But to the end, despite never rising above the position of assistant, she never spoke out openly.
In 1925, the Swedish mathematician Gösta Mittag-Leffler wrote her a letter: ‘Honoured Miss Leavitt, your admirable discovery ... has impressed me so deeply that I feel seriously inclined to nominate you to the Nobel Prize in Physics for 1926’, he had to be informed that she had in fact been dead for four years. As the Nobel Prize is not awarded after the death,, Leavitt never received her nomination.
Instead, Harlow Shapley, suggested in his reply to Mittag-Leffler that the real credit belonged to him, Shapley, for his interpretation of her findings.
Yet one day, perhaps, this important figure in modern astronomy will finally be given the recognition she deserves.
