Author

Dava Sobel

24 key ideas across 3 books, each explained in our own words.

Galileo's Daughter

IDEA 1
A daughter's letters reveal Galileo
Sobel tells the story of Galileo through the surviving letters of his eldest daughter, Virginia, who became a nun called Suor Maria Celeste. Her letters show their deep affection and his private life.
IDEA 2
Galileo saw new worlds
Sobel describes how Galileo used his telescope to discover the moons of Jupiter, the phases of Venus and mountains on the Moon. These findings challenged old ideas. He wrote about them in clear language that ordinary readers could follow.
IDEA 3
His daughter lived in a convent
Sobel describes Maria Celeste's life in a poor convent near Florence. She wrote to her father often, sending him food and care. Her letters show a warm bond and a life of simple duty and faith.

IDEA 1
Sailors could not find longitude
Sobel explains that for centuries sailors could work out their latitude but not their longitude, their east-west position. This caused shipwrecks and huge losses of life. Without a way to know it, even skilled captains could get lost far from land.
IDEA 2
A prize was offered
Sobel describes how the British Parliament passed the Longitude Act in 1714, offering a large prize for a practical solution. Many scientists and inventors tried to win it. The reward showed how serious the problem had become.
IDEA 3
Time could reveal position
Sobel explains that knowing the exact time at home and on board would allow sailors to calculate longitude. But clocks of the time could not keep accurate time at sea.

IDEA 1
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.
IDEA 2
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.
IDEA 3
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.

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