Silent Sky chronicles Henrietta Leavitt’s most famous contribution to astronomy: the Cepheid variable period-luminosity relationship, which discovered in 1912. But what does this mean? It is explained a bit in the play, but if you’re not an astronomy person, then it may take more than a quick snip-it of dialogue to fully understand it. So here is a breakdown of this relationship.

Overall, Henrietta was looking at the overall luminosity (or brightness) of the Cepheids in the Small and Large Magellanic Clouds and found a pattern between the luminosity and the pulsations. In the play, this pattern is related to music, but the actual relationship is not quite as rhythmically interesting. However, the rest of the information in the play is accurate. Henrietta discovered that the more luminous the Cepheid is, the slower it pulses. That is the most simple explanation of her breakthrough, but of course, there are many more factors involved in her overall discovery.

Because of the relative ease in which one can find this relationship, Cepheids can be used to measure the distance to other galaxies. For example, Edwin Hubble used Henrietta’s discovery to measure the distance to the Andromeda Galaxy.

While the this is the most basic information about the Cepheids, it is a simple introduction to the subject matter and is the only relevant information you need to fully understand Silent Sky. If you would like any more information on period-luminosity relationship or Cepheids in general, here are a couple of great resources:

http://www.atnf.csiro.au/outreach/education/senior/astrophysics/variable_cepheids.html

http://astro.wku.edu/labs/m100/PLrelation.html

Women’s education has a long and complicated history. Education was not as accessible to women as it was men and even when women’s colleges came about, the quality of learning was not the same.

                                 Longfellow Hall

One particular women’s college that is relevant to Silent Sky, is Radcliffe College. Many notable women attended Radcliffe, including Henrietta Leavitt herself. Radcliffe was one of the seven sister colleges, which included Barnard, Bryn Mawr, Mount Holyoke, Smith, Wellesley, Vassar, and Radcliffe.

The college’s first president was Elizabeth Cabot Agassiz who ran a school for girls in her Cambridge home 1855-1867. Eventually, in 1879, it was established as the Society for the Collegiate Instruction of Women and nicknamed the “Harvard Annex.” And finally, it was renamed to Radcliffe College in 1894 after Ann Radcliffe who set up the first scholarship fund.

There was always tension between Radcliffe and Harvard. Radcliffe students were sometimes referred to as “Cliffies” and the Harvard students were encouraged to stay away from them.

Finally, during WWII, Harvard began admitting female students. And by 1963, Radcliffe quit giving out diplomas altogether. At this time, female graduates received Harvard diplomas that were jointly awarded by Harvard and Radcliffe.

                    Elizabeth Cary Agassiz House

In 1999, Harvard and Radcliffe officially merged andRadcliffe became Radcliffe Institute for Advanced Study.

Many women’s colleges have similar histories to that of Radcliffe and overall, women were not afforded the same opportunities as men. The federal Office of Education began collecting information on education for 1869-1870. At that time, there were only 63,000 students attaining higher education and 21% of those were women.

It is amazing to see the history of education and to specifically look at the struggles of women at Radcliffe. Henrietta Leavitt was one of the amazing women who defied odds and made something of herself, despite the limitations put on women.

If you have ever wanted to learn a little more about the Theory of Relativity AND you want to make sure you catch every joke in Silent Sky, then look no further! Check out this short video to get a better grasp on the concept: