10 Most Influential Women In Astronomy (Pt.2)

This is a follow up to the first part of the article.

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5. Jill Tarter

If the human race ever makes contact with alien life, we will have a big debt of gratitude to Jill Tarter. Tarter has a long history in the astronomical community. She holds credit for coining the term “brown drawf” to describe a protostar that does not achieve nuclear fusion. But, her main focus in the search for extraterrestrial life. For her doctorate work Tarter helped develop radio telescopes designed to find alien worlds and receive their signals. Through her work she met Thomas Pierson. Together they developed SETI, the premier extraterrestrial life institute.

SETI headquarters is in California and operates a variety of radio telescopes that are constantly searching for life. Tarter has been with SETI its whole life, witnessing key events such as the “Wow signal.” When the film Contact was produced, Tarter provided key information and consulted on the script and filming. In 2012 Tarter retired from extraterrestrial life searching after spending 35 years looking for aliens.  Without Tarter, the human race would not be taking the search for intelligent life as seriously as it now is.

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4. Debra Fischer

Exoplanetary research is all the rage now in astronomy. Ever few months astronomers discover new and exciting worlds that expand our conception of universe’s habitability. One of the most important and influential figures in the search for exoplanets. In 1999 she lead the team that discovered the first multi-planet system outside of our solar system and since racked up an impressive list of a few hundred exoplanets discovered.

Searching for exoplanets is not easy and requires persistence. Fischer and her colleges pour over thousands of numbers trying to discover new planets. Fischer’s skill in looking for planets have earned her the title of principle investigator at the N2K consortium, a multinational exoplanetary research organization. Not content with using old techniques, Fischer is now spearheading the Fiber-optic Improved Next-generation Doppler Search for Exo-Earths project. The FINDS Exo-Earths project is a huge development in using radio telescopes to better search star systems and promises to take exoplanetary research to the next stage. Chances are that if we find a new habitable planet to colonize, Debra Fischer will discover it.

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3. Helen Sawyer Hogg

The fact that many of the women on this list were able to get degrees is in part due to the advocacy and determination of Helen Sawyer Hogg. Considered one of the greatest astronomers of her day, Hogg got her degrees in science when most universities would not allow women to graduate with scientific degrees. In her undergraduate work Hogg loved the stars especially after she viewed a solar eclipse. After graduating with an undergrad degree, Hogg worked with the Harvard Observatory and began studying variable stars.

However, Harvard in the 1920s had a strict policy of not awarding advanced degrees in science to women. Hogg had to actually get her degrees from Radcliffe College while she was still allowed to use Harvard’s equipment. The problems that she faced in obtaining an advanced degree made a huge impact on her life. It set her on a course to make scientific degrees more attainable to women. In her scientific pursuits Hogg was influential in discovering the structure of the Milky Way galaxy and investigating globular clusters. She was one of the first astronomers to travel to world to make varying observations.

During the 1940s, Hogg’s work allowed her to achieve a variety of astronomical positions. She became the head of a variety of Canadian astronomical societies at a time when some colleges would still not give women degrees in the fields. Hogg also headed the American National Science Foundation and helped find the site for the Kitts Peak Observatory. Through her work Hogg was able to help women get into the sciences and was a lifelong advocate of women scientists.

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2. Annie Cannon

Annie Cannon joined Harvard in the late 19th century to work with organizing and classifying stars. Astronomers had a large collection of photographs of stars coupled with their chemical spectra, but nobody really had a good classification scheme for them. Arguments ensued about how to classify stars as Cannon was doing her work. Unfortunately, Cannon also faced a lot of prejudice from the male astronomers who felt that women should not work in academia and should instead be home. Shrugging off the criticism, Cannon developed a reputation as an astute and careful astronomer.

As the debate about stellar classification raged on, Cannon realized that the old system was ineffective. The old system arranged stars by letter types using all 26 Latin letters. Cannon proposed to organize the stars by the strength of their absorption lines which showed which chemicals made up the star. When she began working on the system, Cannon realized that many of the letters were redundant and dropped all of them accept for A, B, F, G, K, M, and O. She kept the letters for those star types but rearranged them to show a descending strength of absorption lines.

The new stellar classification scheme ran OBAFGKM using the absorption lines. The simplicity of the system caught on and Harvard astronomers exclusively used it. Later, scientists discovered that the strength of the absorption lines directly correlated to the temperature of the star. This made stellar classification much more precise and Cannon’s system is still used today. O and B stars are hot blue stars while K and M are cold red stars. In Cannon’s system our sun has a classification of G2.

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1. Henrietta Swan Leavitt

In the early 20th century one of the biggest challenges to astronomy was to find the distance to faraway galaxies. For objects in Earth’s galactic neighborhood astronomers could measure the parallax angle that occurred when they observed stars at different times in the year. However, the farther away an object was from Earth the less reliable parallax measurements became. At the same time astronomers studied variable stars which seemed to have a luminosity that changed over time. Little did they know that the two problems were actually related and it was not until Henrietta Swan Leavitt that the problems were solved.

Leavitt began working at Harvard in 1893 as a “human computer”. Astronomers were doing thousands of observations and needed people to sort and classify their findings.  Leavitt worked with variable stars. As she looked at and classified the stars, she noticed an interesting properties. Brighter variable stars tended to have longer periods between luminosity changes. Plotting the data Leavitt discovered the logarithmic luminosity-period relationship. Because this relationship was precise, it allowed Leavitt and other astronomers to create equations that would tell how far away a star was depending on the logarithmic scale.

This made variable stars the first “standard candles” in astronomy. With a proven technique for determining their distance, astronomers could use variable stars to show how far away distant galaxies were. The luminosity-period relationship was critical for Edwin Hubble, who used the scale to show that galaxies are receding away from us and are red-shifted. Hubble’s discovery was a revolution in cosmological thinking. According to modern science historians: “If Henrietta Leavitt had provided the key to determine the size of the cosmos, then it was Edwin Powell Hubble who inserted it in the lock and provided the observations that allowed it to be turned.”

 

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