- Person
- Vera Rubin
- Lived
- 1928–2016
- Field
- Astronomy
- From
- American
The story
In 1965 Vera Rubin joined the Carnegie Institution's Department of Terrestrial Magnetism in Washington, where she met the instrument-maker Kent Ford. Ford had built an image-tube spectrograph, a device that intensified faint light so that the spectra of objects previously too dim to analyse could be recorded. Wishing to avoid the most crowded and controversial topics of the day, Rubin turned to a quieter question: how do stars move in the outer reaches of galaxies?
In the late 1960s the pair began with the Andromeda galaxy, our nearest large spiral neighbour, measuring how fast stars and gas orbit at different distances from its centre. Their paper on the rotation of Andromeda appeared in The Astrophysical Journal in 1970. Newton's laws predicted that, as in the solar system, outer material should move more slowly than inner material. Instead the outermost stars were moving about as fast as those near the centre. As National Geographic put it, they were travelling so quickly that they should have been flying off into space.
Rubin and her colleagues went on to measure dozens more spiral galaxies and found the same flat rotation curves again and again. A 1980 paper surveyed 21 galaxies of very different sizes, and over her career, the Jewish Women's Archive notes, she analysed the spectra of more than two hundred galaxies. The simplest explanation was that each galaxy sits inside a vast halo of unseen matter. Her calculations showed that galaxies must contain five to ten times more mass than their light reveals.
The idea of hidden mass had been suggested by Fritz Zwicky in 1933, but it had remained on the margins. Rubin's results, confirmed by radio astronomers and later by other methods such as gravitational lensing, became the first persuasive evidence for dark matter. Carnegie Science described her as having confirmed its existence, and many physicists have argued that the work deserved a Nobel Prize.
Rubin herself liked to compare the ratio of dark to visible matter, about ten to one, with the ratio of our ignorance to our knowledge. Identifying what dark matter is remains one of the central questions of physics, pursued by experiments and sky surveys around the world.
Why it matters
Rubin's measurements showed that most of the matter in galaxies does not shine, reshaping cosmology and launching a worldwide search to identify what dark matter is made of.
About Vera Rubin
Astronomer whose measurements of how galaxies spin gave the first persuasive evidence for dark matter, and a lifelong champion of women in science.
More about Vera Rubin
- Vera Rubin found stars orbiting the wrong wayVera Rubin discovered galaxies in which some stars and gas orbit in the opposite direction to the rest, evidence that galaxies grow by merging with smaller systems.
- Vera Rubin broke the barrier at Palomar ObservatoryIn 1965 Vera Rubin became the first woman permitted to observe at the Palomar Observatory, and when told it had no women's bathroom, she taped a paper skirt to the men's room sign.
- Vera Rubin saw that galaxies clump togetherIn her 1954 doctoral thesis under George Gamow, Vera Rubin concluded that galaxies clump together rather than being scattered randomly, an idea ignored for two decades before it became central.
- Vera Rubin was a lifelong champion of women in scienceVera Rubin campaigned for decades to open astronomy to women, saying it was well known that she was available twenty-four hours a day to women astronomers.
Sources
- Vera Rubin Who Confirmed “Dark Matter” Dies Carnegie Science
- Vera Rubin, Pioneering Astronomer, Dies at 88 National Geographic
- Vera Rubin Wikipedia
- Vera Cooper Rubin Jewish Women's Archive
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.