Biography
At the end of the 19th century, the Harvard Astronomical Observatory undertook the ambitious project of trying to catalogue all the stars in the sky. From photographs of the sky obtained by their telescopes, the position, brightness and colour of each of the stars could be established. Due to the poor quality of the photographic plates, the task was tedious and required great visual acuity, great concentration and a huge amount of patience.
The director of the Observatory, Edward Charles Pickering, decided to exclusively hire women to carry out this task, as he was convinced that they had "the skills to do repetitive, non-creative work." What Pickering did not say is that a woman was paid significantly less than a man for doing the same job. Pickering's "harem", as it was soon to be derisively known, consisted of thirteen women. One of them was Henrietta Swan Leavitt.
Little is what we know about Henrietta's life. She was born in 1868 in Lancaster, Massachusetts (United States) into a Puritan family. She graduated from Radcliffe College at the age of 24 and, in 1893, she entered the Harvard Observatory as a volunteer. There she was in charge of studying the so-called variable stars, those whose luminosity changes periodically over time. Throughout her life, she would discover over 2,400.
But Henrietta was not going to settle for being a simple computer, the name by which women who carried out this type of repetitive work were then known. In her study of variable stars, she attempted to find a relationship between their luminosity and their period. The challenge for the time was enormous. If you see some birds in the sky and one of them seems smaller, how do you know if it is really smaller or just flying higher? The same thing happened to Henrietta. By not knowing the distance of variable stars from Earth, she could not know if their greater or lesser luminosity was simply a consequence of being closer or further away from us.
It was then that she noticed a particular type of variable stars called Cepheids, 25 of which clustered in the region known as the Small Magellanic Cloud. Being so close together, Henrietta considered that the distance of all of them to Earth should be approximately the same. It was like saying that, in a flock of birds, they all fly at the same height. Thus she was able to compare the data of these 25 Cepheids and reach the following conclusion: the luminosity of a variable star was greater the longer its period was. Behind this innocent phrase, a tool capable of measuring distances in the Universe was hidden. Indeed, by combining Henrietta's work with other astronomical methods, it was possible to calculate the distance to various Cepheids. Thus, in 1925, the American astronomer Edwin Hubble determined that the Andromeda nebula was actually a galaxy that was about 800,000 light years from us. It was the first of many other galaxies to be discovered in the years to come. Then, in 1929, Hubble himself proved that the Universe was expanding. Thanks to Henrietta, among others, the vision of a static Universe in which there was only one galaxy – the Milky Way – had been shattered.
Unfortunately, Henrietta would never get to taste the joys of her well-deserved success. In 1921, a devastating cancer ended her life in a few months. The news barely spread, to the point that, in 1924, the Swedish mathematician Gösta Mittag-Leffler wanted to propose her as a candidate for the Nobel Prize, without knowing that she had been dead for three years.
Today, asteroid 5383 Leavitt and the Leavitt crater on the Moon are named after her as a tribute.
https://mujeresconciencia.com/2014/07/04/henrietta-swan-leavitt-la-astronoma-calculadora/ (retrieved on 12/02/2022)
