Science

The Glass Universe: 8 key ideas

by Dava Sobel

The core ideas of The Glass Universe, each in under a minute, written in our own words. Want the full depth? Get the book.

1. IDEA 1 OF 8

   Women measured the stars

   Sobel tells the story of the women hired by Harvard College Observatory from the late 1800s to study photographs of stars.

   Known as computers, they made discoveries that transformed astronomy.

2. IDEA 2 OF 8

   Stars were captured on glass

   Sobel explains that the observatory collected hundreds of thousands of glass photographic plates of the night sky.

   The women studied these plates in detail. Studying the plates required patience, since each star had to be found and measured by hand.

3. IDEA 3 OF 8

   A director hired women

   Sobel describes how Edward Pickering, the observatory's director, hired women for this work.

   They were paid less than men but given real scientific tasks. The work opened a door for women in science at a time when few doors were open.

4. IDEA 4 OF 8

   A former maid became an astronomer

   Sobel describes Williamina Fleming, who began as a housekeeper and became a leading astronomer.

   She discovered many new stars. Her rise shows how talent can come from unexpected places when given a chance to work.

5. IDEA 5 OF 8

   Cannon classified the stars

   Sobel describes how Annie Jump Cannon developed a system for classifying stars by their spectra.

   Astronomers still use a version of it. Sorting stars into clear types gave astronomers a common language to compare them.

6. IDEA 6 OF 8

   Leavitt measured the universe

   Sobel explains how Henrietta Leavitt found a link between the brightness and pulsing of certain stars.

   This allowed astronomers to measure cosmic distances. Knowing how bright a star truly is makes it possible to judge how far away it lies.

7. IDEA 7 OF 8

   Payne found what stars contain

   Sobel describes Cecilia Payne's discovery that stars are mostly hydrogen and helium.

   Her finding was at first doubted. Her conclusion changed how astronomers understood the make-up of stars once it was finally accepted.

8. IDEA 8 OF 8

   Their legacy endured

   Sobel argues these women helped open astronomy to women.

   Their work underpins modern understanding of the universe. Today their careful work is still a base for research, and their story reminds us how many contributions were once overlooked.