Today is International Women's Day. To celebrate, here's a post showcasing just a couple of the many really amazing discoveries made by women in astronomy.


Annie Maunder was born in Ireland in 1868. She won a scholarship to go to Cambridge, where she studied mathematics. She was top in her year, but did not receive a BA – they were only awarded to men at the time.

After her degree she began work as a 'computer' at the Royal Observatory, Greenwich. This was low paid, menial work. Luckily for Annie, she became assistant to Edward Walter Maunder, who was in charge to the Photographic and Spectroscopic Department at the Observatory. They collaborated in tracking sunspots – dark spots on the sun created by intense magnetic activity – and eventually married.

Annie resigned her post at the Observatory but carried on working with her husband. Together, they showed that there was a connection between the number of sunspots on the sun and the Earth's climate. The Maunder minimum, an extended period of time during which there was an unusually low number of sunspots, is named after the two of them.

Above is modern version of the butterfly diagram published by Edward Maunder and based on work done with his wife, Annie. The diagram shows that sunspot location varies over the sun's 11 year cycle. And it looks a bit like a line of butterflies – hence the name.

For more about the butterfly diagram and sunspot cycles, head over to NASA.


Caroline Herschel was the first woman to discover a comet – and went on to find eight in total. Though she is best known for her comets, she also discovered several deep-sky objects, including the Sculptor Galaxy.

Caroline was born in 1750 in Hanover, Germany. From the age of 22 she lived with her brother, William, in England. After discovering Uranus, William became an astronomer to the Royal Family, and Caroline his assistant. King George III granted Caroline a £50 salary for her work, making her the first woman to earn a living from astronomy.

Caroline discovered the Sculptor Galaxy, or NGC 253, in 1783. It lies about 13 million light years from Earth and is undergoing a huge burst of star formation. It's a dusty galaxy – only when looking at it in infrared can we see the true extent of the intense star formation within. This image, taken by the European Southern Observatory's VISTA telescope reveals the galaxy's spiral arms and bright core.

Caroline also independently discovered Messier 110, a satellite of the Andromeda Galaxy.


Today, of course, there are many more women working in astronomy. The barriers to entry are not the same as they were in Caroline Herschel's or Annie Maunder's days. But we've still got a long way to go before there are equal numbers of men and women working in science, engineering and technology. (According to the UKRC, for example, women make up only 15.5% of SET professionals in the UK.)

To find out more about International Women's Day see the website or search for #womensday on twitter.