Henrietta Leavitt: The Woman Who Measured the Universe

In the wake of the Women’s March on Washington,  International Women’s Day seems to be enjoying a bit of a resurgence this year.

If you read my writing, you’ll know that I’m not a fan of gross statistics that describe large groups of people as if they were homogeneous. As such, you might imagine that I wouldn’t see much point in a holiday that purports to celebrate over half of humanity.

Typically, you’d be right. But a couple days ago, while reading on Fivethirtyeight, I learned about Henrietta Leavitt–an astronomer in all but title who, in 1912, discovered how to use variable stars to measure distances in space. Her story struck a chord with me, and I thought it might be cool to write a little bit about it.

Leavitt discovered that there was a relationship between the brightness of a variable star and its period of pulsation. The length of that period can be used to find the star’s intrinsic brightness, or how bright the star would be at a common distance. From there, she was able to compare the star’s intrinsic brightness to its measured brightness and calculate its distance.

Before her, scientists were able to measure about 100 light years out into space. Leavitt’s discovery helped pushed that boundary to 10 million light years.

Leavitt was, for a long time, largely uncredited for her contribution to our knowledge of the universe. Her boss, Edward Pickering, published her work under his own name–a pattern familiar to women of the era–and referred to her only as the person who “prepared” it. Leavitt has since been credited for her work and posthumously biographied multiple times.

Anyway, I thought she–and by extension, the too-often anonymous female contributors of the past–deserved a shout out. Part of the joy of meticulous work is getting to show off a finished product that makes people say, “You did what? Why?” It’s a shame Leavitt didn’t get to enjoy that in her lifetime. But better late than never, I suppose.

Happy International Women’s Day.