Pulsating RS Puppis, the brightest star in the image center, is some ten times more massive than our Sun and on average 15,000 times more luminous. In fact, RS Pup is a Cepheid variable star, a class of stars whose brightness is used to estimate distances to nearby galaxies as one of the first steps in establishing the cosmic distance scale. As RS Pup pulsates over a period of about 40 days, its regular changes in brightness are also seen along its surrounding nebula delayed in time, effectively a light echo. Using measurements of the time delay and angular size of the nebula, the known speed of light allows astronomers to geometrically determine the distance to RS Pup to be 6,500 light-years, with a remarkably small error of plus or minus 90 light-years. An impressive achievement for stellar astronomy, the echo-measured distance also more accurately establishes the true brightness of RS Pup, and by extension other Cepheid stars, improving the knowledge of distances to galaxies beyond the Milky Way. via NASA
Well, yeah, any guy could get that. (Heh, no.) But it took a woman, Henrietta Swan Leavitt, to notice it and its significance for the first time in history.
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I don’t get out at night anywhere near as much as I’d like, just to look up at the stars in the night sky. What I have been doing lately is watching a lot of YouTube and Netflix documentaries on the cosmos. It struck me how certain male astronomers throughout history have become household names, like Gallileo and Edwin Hubble, but I’d be willing to bet a bucket of dark matter that not all that many people have even heard of Vera Rubin. So, I got to thinking. In my video-watching, several women astronomers have been prominently featured; why not make up a short list of those incredible and very significant women of astronomical science and do a little write-up on them?
I’ll start with Henrietta Swan Leavitt (1868-1921), because of all the ones I’m going to list, I think her contribution to our understanding of the stars and galaxies was of singular importance. We’ve all looked up at the stars and we all see stars that are brighter than others, and just like car headlights up close or far away we intuit, from experience, that the brighter they are the closer they are. So, that goes for the stars too, right? The brighter, the closer. Nope, not necessarily. As we now know, some stars are intrinsically brighter than others, and a dim star, as seen by our naked eye, may actually be closer to Earth than a much brighter one immediately adjacent. So how could we figure which was what? Henrietta Swan Leavitt did just that.
Encyclopaedia Britannica
Leavitt’s outstanding achievement was her discovery in 1912 that in a certain class of variable stars, the Cepheid variables, the period of the cycle of fluctuation in brightness is highly regular and is determined by the actual luminosity of the star. The subsequent calibration of the period-luminosity curve allowed American astronomers Edwin Hubble, Harlow Shapley, and others to determine the distances of many Cepheid stars and consequently of the star clusters and galaxies in which they were observed. The most dramatic application was Hubble’s use in 1924 of a Cepheid variable to determine the distance to the great nebula in Andromeda, which was the first distance measurement for a galaxy outside the Milky Way. Although it was later discovered that there are actually two different types of Cepheid variable, the same method can still be applied separately to each type.
Without Leavitt’s work (and tedious it was, so all the more kudos to her) we might still be guessing just how far away the stars actually are.
Next, I want to mention Caroline Herschel (1750-1848), younger sister of telescope maker William Herschel, and the first woman to discover a comet. [bolding mine]
Caroline Herschel was born on March 16, 1750 in Hanover, Germany. Her father Isaac was a talented musician. Isaac Herschel encouraged all six of his children to train in mathematics, French and music. Caroline's mother did not see the need for a girl to become educated and preferred to make Caroline a house servant to the rest of the family.
At the age of ten Caroline was stricken with typhus. The disease permanently stunted her growth. Her parents concluded that she would never marry but would live her life as an old maid. Caroline remained in her parents' home until, at the age of twenty-two, her brother, William took her to live with him in Bath, England. Caroline became her brother's housekeeper.
William was an accomplished musician and a conductor. He gave Caroline voice lessons and trained her in mathematics as well. Caroline became a well known soprano and began to sing professionally. William's hobby was astronomy and he devoted most of his free time to making more and more powerful telescopes with which to look deeper into space.
William's reputation as a telescope maker grew to such an extent that he quit his job as a musician and devoted all of his time to the making of telescopes and to astronomy. Caroline began to help her brother in the manufacture of telescopes and to share his passion for astronomy. Caroline first served as her brother's apprentice then began to function more and more on her own. She helped her brother develop the modern mathematical approach to astronomy.
In 1783 Caroline Herschel discovered three new nebulae ( hazy clouds where stars form). Between 1786 and 1797 she discovered eight comets. In later years, Caroline catalogued every discovery she and William had made. Two of the astronomical catalogues published by Caroline Herschel are still in use today. On her ninety sixth birthday, Caroline Herschel was awarded the King of Prussia's Gold Medal of Science for her life long achievements.
There are several more women astronomers on my “short list” for today, and I’m going to get briefer as we go along, but this is not to diminish in any way their contributions to the science of the stars nor to exclude the many other women astronomers I have not the space to include here, along with the rightful appreciation they all deserve. It’s just that the following women astronomers are the ones that I’m most recently cognizant of.
What is the universe made of? Thanks to Vera Rubin (1928-2016) we now know that we don’t know, exactly. We know that whatever it is, we can’t see it, can’t say exactly what it is or why it’s there, and can’t even come up with a better name for it than Dark Matter. But we do know it’s there.
Astronomer Vera Rubin changed the way we think of the universe by showing that galaxies are mostly dark matter.
On a dry and clear night at the Kitt Peak Observatory in the mountains of southern Arizona, Rubin closely observed the spectra of stars in the Andromeda Galaxy to determine their velocities. Conditions for observation were perfect, if not for the heat rising from the Sonoran Desert below. Rubin alternated between eating ice cream cones and developing exposures just taken by her colleague, Kent Ford, in the observation deck. It was their first successful night determining how fast the galaxy's stars rotate around its center (what astronomers call the rotation curve). It was 1968, and the motions of galaxies were still a mystery.
"The surprises came very quickly," Rubin recalled years later in a written account of her life. "By the end of the first night, we were puzzled by the shape of the rotation curve."
The rotation curve was flat, meaning the stars in the outer spirals of the galaxy were orbiting at the same speed as stars near the center. More alarming, the stars in the outer spirals were orbiting so fast they should have flown apart. The mass of visible stars wasn’t enough to hold the galaxy together. There was an extraordinary amount of matter missing.
The Andromeda Galaxy became the first of many galaxies with unexplainable rotation curves, which Rubin observed with Ford. Rubin's decades of discoveries revealed there was much more to the universe than meets the eye. The cosmos was chock-full of dark matter.
Harking back to comets, Carolyn S. Shoemaker (1929-2016) and Heidi Hammel (b. 1960) were instrumental in bringing us the most stunning visuals of a comet in action, a comet which, had it hit the Earth instead of Jupiter, we would not even be here today to talk about it.
I’ve been to one observatory in my life, the Griffith Observatory, perched on the hills between Glendale and Hollywood. Laura Danly is the observatory’s curator. Thanks to Laura, more women have been taking up professions in astronomy.
Dr. Laura Danly is an American astronomer and academic. Currently, Danly serves as Curator at Griffith Observatory in Los Angeles. Prior to her current positions, she served as chair of the Department of Space Sciences at the Denver Museum of Nature & Science.
Previously, Danly held academic posts at the University of Denver (where she served as assistant professor), and at Pomona College (where she served as visiting assistant professor). In these positions, she developed curricula focusing on astronomy, archaeoastronomy, solar physics, astrophotography and astrobiology.
Danly spent several years at the Space Telescope Science Institute in Baltimore, Maryland, where she held a variety of positions including project scientist for education, assistant astronomer and Hubble Fellow. In addition, Danly conducted post-doctoral research at the STSci.
In 1991, Danly founded the Women's Science Forum to encourage young women to pursue careers in science by providing opportunities to meet and ask questions of leading women scientists and engineers and take part in hands-on activities to explore opportunities in various career disciplines. In 1993, Danly co-authored The Baltimore Charter for Women in Astronomy to address the concerns of women as a minority group in the field of astronomy.
Danly received a B.A. in Physics from Yale University, and earned a Ph.D. in Astronomy from the University of Wisconsin–Madison.
Laura Danly has also been a common guest scientist on the documentary series The Universe in all seven series and on How the Universe Works.
(By the way, Heidi Hammel, Laura Danly, and the last two I’ll be talking about today, Jill Tarter and Michelle Thaller, are all tied for first place in my search for the Fantasy Wife. I admire them that much. What can I say?) ¯\_( ͡❛ ͜ʖ ͡❛)_/¯
I first became acquainted with Michelle Thaller from watching The Universe, a series which covers every corner of everything we know about this big ol’ place we live in. Dr. Thaller is, more than anything else to my mind, a science communicator. We sure need more people like her if we are to survive as a species into the future. Below, she talks a little about herself.
Describe the first time you made a personal connection with outer space.
I recently spoke to my mother about this, and she confirms that there never seemed to be a time when I wasn't obsessed with space. No one can really figure this out. Neither one of my parents are particularly inclined to astronomy, although my dad did teach geography at the local college and was always telling me about rocks and landforms. Basically, as soon as I was able to talk, I started pointing at the sky and going on endlessly about the Sun and the stars. But there does seem to be something hard-wired into my family. I have since found several relatives of mine who also work for NASA. We had never met before, but we could all trace ourselves back to the same relative, (my great-grandfather) an Austrian/Italian sailor who immigrated to the United States.
How did you end up working in the space program?
At first I pursued a purely academic track, and I assumed I would become a professor at a university, but like a lot of people my plans had to be modified when I fell in love and wanted to actually be in the same location as my boyfriend (now my husband). Andrew and I met while I was in Australia, taking data for my Ph.D. research. I was living on the east coast at the time, and such a long distance relationship was hard. So Andrew made a huge sacrifice by leaving his tenured professorship in Australia to find a job at JPL. This at least put us on the same continent. Later, I was able to find a post-doctoral position working for the Spitzer Space Telescope at JPL. That got my foot in the door on a NASA mission, and the rest followed naturally.
[...]
What is an Assistant Director of Science for Communications?
Beats me. This is actually a very real part of being a scientist at NASA -- many of our jobs are not terribly well defined. While this can be frustrating, it also allows a position to never become stale, but rather to change and grow with the abilities and expertise of the person holding that position. Officially, I represent the four science divisions here at GSFC: Earth Science, Planetary, Heliophysics and Astrophysics. My job is to get the four divisions to work together to do better public outreach and education, but I am also tasked to encourage scientists to work better together internally as well. (Scientists tend to get stuck in tribes with other people who share their same specialty. For example, as an astronomer, I had never gone to a planetary science convention, and I knew next to nothing about Earth science.) At NASA we've got to break down those barriers to be able to function as a whole.
I’ll close my tribute to Women in Astronomy with Jill Tarter, who is still very much working on the question “Is anybody out there?”
Dr. Jill Tarter is Chair Emeritus for SETI Research at the SETI Institute in Mountain View, California and serves as a member of the Board of Trustees for that institution. Tarter received her Bachelor of Engineering Physics Degree with Distinction from Cornell University and her Master’s Degree and a Ph.D. in Astronomy from the University of California, Berkeley. She has spent the majority of her professional career attempting to answer the old human question “Are we alone?” by searching for evidence of technological civilizations beyond Earth.
She served as Project Scientist for NASA’s SETI program, the High Resolution Microwave Survey and has conducted numerous observational programs at radio observatories worldwide. She is a Fellow of the AAAS, the California Academy of Sciences, and the Explorers Club, she was named one of the Time 100 Most Influential People in the World in 2004, and one of the Time 25 in Space in 2012, received a TED prize in 2009, two public service awards from NASA, multiple awards for communicating science to the public, and has been honored as a woman in technology. She is an Adjunct Professor in the Department of Physics and Astronomy at USC, Asteroid 74824 Tarter (1999 TJ16) has been named in her honor. She is the Jansky Lecturer in 2014.
Since the termination of funding for NASA’s SETI program in 1993, she has served in a leadership role to design and build the Allen Telescope Array and to secure private funding to continue the exploratory science of SETI. Many people are now familiar with her work as portrayed by Jodie Foster in the movie Contact.
In a way, Dr. Tarter is close to me. The Allen Telescope Array is located in Hat Creek, CA, not at all far away from where I live.
The Allen Telescope Array is the first radio telescope to be designed from the ground up to be used for SETI searches.
That situation has changed. Thanks to the far-sighted benevolence of many donors, including technologists Paul Allen (co-founder of Microsoft) and Nathan Myhrvold (former Chief Technology Officer for Microsoft), the first 42 elements of the ATA are conducting SETI searches every day of the week.
The instrument, called the Allen Telescope Array, is situated at the Hat Creek Observatory, located in the Cascade Mountains just north of Lassen Peak, in California.
Thanks so much for letting me share this with you today. Even though I’m just a “crusty old geezer” these women, along with countless others, are a never-ending inspiration to me.
Now It's Your Turn
Are there any women scientists you find particularly notable or inspiring? What have you noted happening in your area or travels? As usual post your observations as well as their general location in the comments.
Thank you.
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