In this video Nicholas Mee tells the story of Henrietta Swan Leavitt whose work on Cepheid variable stars led the way to our understanding of the vast scale of the universe. Leavitt referred to Cepheid variables as standard candles. They remain an important rung in the cosmic distance ladder.

Our current understanding of the scale of the universe dates back almost a hundred years to the 1920s, and the work of a relatively unknown female astronomer Henrietta Swan Leavitt was key to the advances made in that decade. Computers were originally people, mainly women, who were employed to perform repetitive and tedious calculations. Charles Edward Pickering at the Harvard College Observatory employed a team of about 80 women in the 1890s and early 20th century who were employed to perform astronomy calculations and Henrietta Swan Leavitt was one of Pickering's computers.

Leavitt's work did indeed lead to a revolution in our understanding of the scale of the universe but unfortunately she died of stomach cancer in 1921 at the age of 53 just too soon so see this revolution come about. In 1924 Edwin Hubble found Cepheid variables in the Andromeda nebula and used Leavitt's relationship to show that they are much more distant than any of the stars in our own galaxy and thereby demonstrated that the Andromeda nebula is in fact a separate galaxy to our own. By the end of the decade Hubble had used Leavitt's standard candles to show that the Milky Way galaxy is just one amongst a vast number of other galaxies and indeed that the universe itself is expanding.

Henrietta Swan Leavitt's discovery led to a total re-evaluation of the size of the universe. Her discovery still forms an important rung of the cosmic distance ladder which is the scheme that is used to measure the size of the universe.

Henrietta Swan Leavitt never obtained a doctorate or an academic position. However, if she had live just a few more years she almost certainly would have been nominated for a Nobel Prize. Many women have made important contributions to science and astronomy in particular, but they have been slow to receive the credit they deserve.

Nicholas Mee discusses another great female astrophysicist Cecilia Payne in this video: [ Ссылка ]

0:00 Introduction
0:01 Women of Science
0:20 Henrietta Swan Leavitt
2:56 Variable Stars
4:15 Intrinsic Luminosity
5:40 The brighter a Cepheid Variable the longer the period of time over which it cycles in brightness.
6:04 A Measuring Rod to the Stars
7:06 Standard Candles
9:04 The Cosmic Distance Ladder
10:47 The Cosmic Mystery Tour

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