We live in a world where everything about us and around us has been turned in to data.

This data is collected, stored, retrieved and processed by computers – electronic devices like smartphones, laptops, smart watches and tablets. These devices talk to each other via the internet, share our data and deliver us some personal benefit, like the answer to a question, up-to-the-minute news, a song we had forgotten, a message from a friend. And all this happens at speeds we can barely comprehend, delivering apparently instantaneous results.

But before the electronics revolution of the mid-20th century, a computer was quite a different thing altogether. A computer was a person. A human computer would do calculations just like a modern electronic computer does now, but at the speed of human brain and hands.

In the 1880s, the observatory at Harvard University used a team of human computers to process the data stored in their collection of approximately half a million photographic plates taken of the stars. These computers were educated and highly trained women, collectively known as the Harvard Computers, and they used equations to calculate the size, temperature, composition and brightness of stars.

And yes, it is true that modern electronic computers can carry out complex calculations at a rate the Harvard Computers could not hope to match. But the Harvard Computers’ mathematical skill paired with their human perception revealed much about the workings of the universe that may have otherwise gone unseen for decades, and much of it is still in use today.