Published on April 18th, 2011 | by Yellow Magpie1
Henrietta Swan Leavitt: She Changed The World But Paid The Price
While Edwin Hubble may have garnered all the plaudits for discovering other galaxies, the true genius that did all the work is often forgotten. Punished because of her sex, Henrietta Swan Leavitt’s work has changed the nature of astronomy forever.
Science, like virtually every aspect of humanity, is bound by our mindset. Sometimes we can be confined by convention and concepts that we take for granted. The greatest thinkers have questioned the status quo and have revealed our world to be much different than we imagine. Henrietta Swan Leavitt was one such person.
The Problem Of Measuring Distance
Scientists were faced with a very difficult problem when it came to measuring distance and time in the Universe. One of the earlier methods of calculating distance, was through parallax. This basically used two perspectives to measure objects. So for example, a star’s position was noted in both summer and winter. The angle between the two positions allowed astronomers to measure distances between stars in Space.
However, measuring distance using parallax had a significant drawback. The further away the objects were, the smaller the difference in perspectives. Certain objects could not be measured as they were too far away.
A Universe With Only One Galaxy
Prior to Leavitt many scientists maintained that the Milky Way was the only galaxy in the Universe. Although there were those that thought otherwise, neither side could conclusively prove their argument one way or another as it was possible to use evidence to support both sides.
This debate would not be solved until the 1920’s when an unsung woman would change the nature of the world for ever.
The Genius Of Leavitt
Henrietta Swan Leavitt changed all this as she helped to conclusively prove that there were a myriad of galaxies in the Universe. She worked as a so-called ‘computer’ counting images of stars on plate photographs taken from telescopes throughout the world.
With painstaking effort and detail Leavitt marked out the subtle details of the stars and recorded them. During the course of this work, she would come up with a remarkable idea that centred on objectively finding the true brightness of the stars.
The Cepheid Variable
One particular star that caught her attention is called a Cepheid variable. Cepheid variables are pulsing stars that populate the Universe. The genius of Leavitt was that she recognised that there was a distinct correlation between their luminosity and the rate at which they pulsed. To simplify, there was a relationship to the number of times they blinked and their brightness.
Once Leavitt knew this she could find Cepheid variables that pulsed at the same rate. These stars, even if one shun brighter than the other would burn at the same luminosity. The only difference was that the dimmer star was farther away. Using this Leavitt could calculate the distance between the brighter and dimmer stars. Leavitt had discovered a way of measuring stars that lay well beyond the limitations of parallax and the standard candle, which is used to measure the vast distances of Space, was born.
But Leavitt was a second class citizen. She, like countless others, was forbidden from using a telescope. Why? Because she was a woman and women were believed to be intellectually inferior to men. And so in this sexist environment she couldn’t progress her work.
Instead her work was taken up by the visionary and highly egotistical Edwin Hubble. Hubble, using the latest in telescopic technology, used Leavitt’s work to find a Cepheid that was outside of the Milky Way Galaxy.
The variable was located in our nearest neighbouring galaxy, in what would become known as Andromeda. The Andromeda galaxy is over 2.5 million light years away. Or if you look at it another way – what we see in the sky as Andromeda is what the galaxy looked like over two million years ago. When we look up at Andromeda in the night sky we are actually receiving the light that started off on its 2.5 million year journey before the existence of the modern human.
Through Leavitt, Hubble had shattered the belief that the Milky Way was an island galaxy, the only galaxy in the Universe. One can only speculate what Leavitt would have achieved in a non-sexist world but stuck in the early 20th century, it was clear that being a woman prevented her from realising her potential.
As it stands, despite all of this, Leavitt managed to change the world, she may not have received the Nobel Prize for Physics but thanks to her we now have a better understanding of the Universe, and the world that we inhabit.
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