Vera Cooper Rubin, the woman who discovered the dark side of the Universe

Vera Rubin looking through a telescope at Vassar College in 1947.
Credit: American Institute of Physics; Emilio Segrè Visual Archives
Vera Rubin looking through a telescope at Vassar College in 1947.
  • Vera Rubin looking through a telescope at Vassar College in 1947.
  • Vera Rubin and colleagues preparing the 72-inch telescope at Lowell Observatory in Arizona in 1965.
  • Mrs. Rubin studying photographic plates of galaxies in the early 1970s.
  • Portrait of Vera Rubin taken in 2003.
Vera Cooper Rubin, the woman who discovered the dark side of the Universe

The astronomer Vera Rubin isn’t a name to the general public. Nevertheless, she made some major discoveries, which became important research topics in astronomy.

An early passion

Vera Cooper Rubin was born in Philadelphia in 1928. Her family then moved to the Washington, DC area in the late 1930s. From the age of ten, Vera was fascinated by the stars. When she was twelve, her mother persuaded the municipal library to let Vera borrow astronomy books from the adult section. With her father, she even built her first telescope.

From that point, her choice was made: she wanted to become an astronomer. But her teachers tried to discourage her, and advised her to choose a simpler discipline. Even members of her family made fun of her taste for astronomy.

As luck would have it, her parents encouraged her to pursue her dreams, and even helped her achieve them.

Simple questions that have great impact

She studied astronomy at Vassar College and earned her bachelor of arts degree in 1948. During her master’s studies, Vera asked herself a simple question: do galaxies have a movement of their own if we remove their movement brought about by the expansion of the Universe? She discovered that the galaxies in our local group are in rotation around a common point.

That finding was not popular with her male colleagues. But time would prove Vera right: the movement of the galaxies towards a great attractor is now admitted by the entire astronomical community.

In her doctorate, Vera demonstrated that galaxies are not uniformly distributed through the Universe, but rather clump together to form a filamentary fabric. Despite the misgivings of her colleagues, on their initial publication, those results would be confirmed fifteen years later.

Discovering dark matter

In the 1960s, Vera would ask herself another question that seemed unremarkable, but that would have a major impact in astronomy. She wondered why spiral galaxies have varied shapes. She suspected that the rotation of the stars might play a role. She discovered that the rotation speed of stars in the Andromeda galaxy does not decrease as they move away towards the outer regions of the galaxy, as was thought at the time. On the contrary, the speed of stars’ rotation remains constant. The only way of explaining this observation is to suppose that the galaxy is surrounded by a halo of dark matter that affects the movements of stars.

This discovery of dark matter was fundamental, and revolutionized the ideas of the period. But here again, her male colleagues would attempt too refute – in vain – her hypothesis.

Today, the existence of dark matter is recognized, and the quest to discover the nature of that matter is one of the principal research topics in current physics.

A bizarre galaxy

In 1992, Vera became interested in a strange galaxy: NGC 4550. She discovered that this galaxy has a group of stars that turns in one direction and another that turns in the opposite direction. To explain this strange observation, the galaxy must have been formed further to a collision. Astronomers thus understood that galaxies are created by collisions and fusions of smaller elements.

An exceptional career

Vera Rubin’s career was exceptional in every way. The questions she raised profoundly changed our vision of the Universe.

Had she been a man, the discovery of dark matter alone would have earned her the Nobel Prize – but unfortunately, her nomination for that award was always ignored. Happily, though, her work and her talent came to be recognized towards the end of her career, and U.S. president Bill Clinton presented her with the National Medal of Science in 1993. Further, Vera Rubin in 1996 became the second woman, after Caroline Herschel in 1828, to receive the Gold Medal of the Royal Astronomical Society in London.

Something worth noting, Vera’s four children all earned doctorates in scientific fields. Her daughter, Judith, who died in 2014, followed in her footsteps to become an astrophysicist.


Many women scientists are unfortunately unknown to the general public, despite important discoveries. Learn more about some of them:

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