Vera Rubin…

If you have read A Bloke In A Hat from 2014 then you will know the names of a few female scientists. Science has been dominated by men but I think that things have now improved such that nearly as many women as men apply to take science courses at University. One very great female scientist died aged 88 on Christmas Day and her name was Vera Rubin. Her New York Times obituary said that she…

…transformed modern physics and astronomy with her observations showing that galaxies and stars are immersed in the gravitational grip of vast clouds of dark matter…

She was an outspoken voice in support of equality for the sexes and had four children each of whom earned a PhD. You may occasionally feel a little pressure to match the achievements of your brothers and sisters but imagine being the fourth child and the only one yet not to have received a PhD. It puts that Merit in Grade 3 piano into perspective!

Amongst other things, Rubin studied the Andromeda galaxy. This is a spiral galaxy like the Milky Way and our nearest neighbouring galaxy. It is also on a collision course with our galaxy, although not expected to collide for another 4.5 billion years (which is roughly the age of our planet). Her observations led her to what is known as the galaxy rotation problem. Galaxies are held together by the gravitational pull of the stars and other matter from which they are formed, however, they are spinning so fast that they ought to fly apart. This means that either Newton’s equations for gravity are wrong or some other explanation is holding the galaxies together.

Rubin calculated that galaxies would have to have about ten times the mass that we think they have (from counting their visible stars) to hold together as they do. She suggested that some invisible, or dark, matter must be holding the galaxies together. Although controversial at the time, later research has supported her findings. The idea that dark matter makes up about 27% of the observable Universe is now widely held to be the case by astronomers.

Questions…

1. What is a galaxy?
2. From which element are most stars made?
3. What process within the Sun produces its heat and light energy?
4. What is the gravitational constant on Earth?
5. Name a famous female scientist other than Vera Rubin (or Marie Curie) and say in which discipline they worked.