Measuring the Universe with Henrietta

This is a valentine for a woman history forgot.

A woman named Henrietta who figured out how we can measure the universe.

So, let’s put the universe aside for a moment. And get some vitals on Ms. Henrietta Swan Leavitt.

Ms. Leavitt lived a short life. A life that started in the summer of 1868. And ended (of cancer, possibly stomach) in the winter of 1921. She was a child of Massachusetts. Had six siblings and some hearing difficulties. Went to public school and private college. Never married.

But in her short life, Ms. Leavitt worked on the stuff of the universe.

As a senior at the Society for Collegiate Instruction of Women (which would become Radcliffe, which would become part of Harvard), Ms. Leavitt took an astronomy class.

And astronomy had a challenge on its hands: No one really knew how to measure the distance from us here on earth to many of the stars out there in the sky.

The astronomy class struck a chord with Ms. Leavitt. So, she went over to the Harvard College Observatory.

And while male astronomers gazed up at the night sky, Ms. Leavitt and her female co-workers stared down at photographs of the night sky. For some 30 cents an hour, the women were to measure the position and brightness of the stars in the photos.

Ms. Leavitt, however, sprung past her job description.

While comparing photos of the same patches of sky, she discovered not only 2,400 stars that vary in brightness (earning her the nickname ‘variable-star fiend’). But also that the variation rate of a star’s brightness indicates how bright it intrinsically is.

When you know the brightness of a star, you can begin to calculate the distance to a star. And when you can do that, you can – as science writer Simon Singh put it – “start to measure the universe.”

Edwin Hubble used Ms. Leavitt’s findings. And the Swedish Academy of Sciences tried to nominate her for a Nobel Prize in 1924. But she had been dead for three years.

The history books barely hold a footnote for this variable-star fiend. Maybe because she was a woman discounted in a man’s world. Maybe because she died so young.

But the universe isn’t measured by history books alone.

When we can count those who have been discounted. Regard what has been disregarded. And remember those who have been forgotten.

Then perhaps we, like Henrietta Swan Leavitt, will have measured the universe.

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