Vera Rubin: Dark Matter
Rubin is the astrophysicist who confirmed the existence of dark matter in the atmosphere. She was also an ardent advocate for equality for women in astronomy, and in society. A role model for many, Rubin overcame high cultural barriers to succeed in observational astronomy. Rubin’s greatest passion was for spiral galaxies. It was her measurements of the speeds at which stars orbit around galactic centers, arguably her most important work, that confirmed theories of dark matter. It had long been assumed that this rotation would slow down with distance from a galaxy’s center, just as the planets orbit more slowly the farther they are from the Sun. She worked with astronomer Kent Ford in the ’60s and ’70s, when they discovered the reasoning behind stars’ movement outside of the galaxy. She’s dubbed a “national treasure” but remains without a Nobel Peace Prize due to Ford claiming most of the credit.
But what is dark matter? According to NASA: “We are much more certain what dark matter is not than we are what it is. First, it is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the universe to make up the 27% required by the observations. Second, it is not in the form of dark clouds of normal matter, matter made up of particles called baryons. We know this because we would be able to detect baryonic clouds by their absorption of radiation passing through them. Third, dark matter is not antimatter, because we do not see the unique gamma rays that are produced when antimatter annihilates with matter. Finally, we can rule out large galaxy-sized black holes on the basis of how many gravitational lenses we see. High concentrations of matter bend light passing near them from objects further away, but we do not see enough lensing events to suggest that such objects make up the required 25% dark matter contribution.”