Category Archives: lectures

Kelly Beatty’s history of Pluto

The history of Pluto goes way back before it became a tiny twinkle in Clyde Tombaugh’s blink comparator. Kelly Beatty, a senior editor at Sky & Telescope magazine, told the story of Pluto in his keynote address Saturday at the annual banquet of the Seattle Astronomical Society.

Scheiderer and Beatty

Kelly Beatty, right, with Seattle Astronomy’s Greg Scheiderer at the annual banquet of the Seattle Astronomical Society January 28, 2017. Astronomy guys love their astronomy ties. Photo: Greg Scheiderer.

In a way, according to Beatty, the hunt for Pluto dates back to the late 1700s. The Titius–Bode law (since repealed) of the distances to the planets from the Sun worked well, with one exception: according to the law, there should be a planet between Mars and Jupiter. Thus a group of astronomers calling themselves the “celestial police,” led by Franz Xaver von Zach, set out to find this elusive object. They did it; on New Year’s Day, 1801, Giuseppe Piazzi discovered Ceres. It wasn’t long before Juno, Vesta, and Pallas we found. At first all four were labeled planets, but now they’re known as the four largest asteroids—and possibly the first celestial objects to be demoted in status.

Dumb, fool luck

Lowell blink comparator

Blink comparator used by Clyde Tombaugh at Lowell Observatory to discover Pluto. Photo: © User:Pretzelpaws / Wikimedia Commons / CC-BY-SA-3.0.

Later, because of irregularities in the motion of Uranus, astronomers predicted another planet out beyond its orbit. But even after the discovery of Neptune in 1846, anomalies remained. Percival Lowell and William Pickering predicted there was yet another planet beyond Neptune. The hunt was on for Planet X, and Pluto was finally discovered by Clyde Tombaugh in 1930. We soon learned that Pluto was pretty small, which lent some irony to its discovery.

“Pluto didn’t have any effect on Uranus and Neptune at all,” Beatty said. “It turns out that the mathematics were incorrect, the positional accuracy of those early observations was bad. There was no basis to the prediction whatsoever, and by dumb, fool luck Clyde found the planet Pluto that he had been seeking within about six degrees of the predicted position. Freakingly by accident.”

We didn’t know a whole lot about Pluto for a long time. The best photos we could get were fuzzy Hubble Space Telescope shots. Astronomers found methane ice on Pluto in 1976, and its moon Charon was discovered in 1978. Pluto’s atmosphere was discovered in 1988 when it occulted a star.

Pluto on thin ice

“In 1998 the bottom fell out of the pro-Pluto movement,” Beatty said. The beginning of the end was the discovery of another distant object in what we now call the Kuiper Belt. Astronomers figured that there had to be more out there than just Pluto, and we now know of more than 1,800 of them. Many of these objects are locked in a 3:2 orbital resonance with Neptune, just like Pluto.

“Not only is Pluto not alone, it’s not even unique in its orbit,” Beatty said. “Things did not look good for Pluto and its planet status.”

The International Astronomical Union (IAU) started hearing chatter that Pluto should not be a planet, and in 1999 it passed a resolution declaring that it still was. Brian Marsden, who headed the minor planet center of IAU, really wanted to classify Pluto as an asteroid, according to Beatty.

Then, in 2005, Eris was discovered. At the time it appeared to be bigger than Pluto, though we now know it is slightly smaller. It was bureaucracy that finally knocked Pluto off the planet list. Different committees at the IAU name planets and asteroids, so to decide to which committee to refer the new discovery for naming, they had to decide what it was. This led to the new definition of planet, under which neither Eris nor Pluto fall. The IAU declared Pluto to be a dwarf planet in 2006.

Beatty is not fond of the IAU definition of planet: an object that orbits the Sun, has enough mass to be round, and has “cleared the neighborhood of its orbit.”

“It’s a really stupid definition,” Beatty said, mostly because it’s hard to know the mass of faraway objects, and so the definition is difficult to apply. Plus he finds it puzzling that a dwarf planet is not a planet.

“We have dwarf stars which are considered stars.” he pointed out. “We have dwarf galaxies that are considered galaxies. A chihuahua is still a dog.”

New Horizons


New Horizons close-up of Pluto, one of the first and most iconic images from the mission. Photo: NASA.

Planet or not, the New Horizons flyby of Pluto in 2015 gave us a ton of new information about it and its moons. Beatty shared numerous photos of and findings about Pluto from the mission. It’s mostly made of rock, and might have liquid water below its surface. The surface features are mostly hard-frozen water ice, with a little frozen nitrogen, methane, and carbon dioxide mixed in.

Most fascinating is evidence of geology happening right now in the form of flowing nitrogen ice.

“Pluto’s surface, against all odds, out in the frozen corner of the solar system,” Beatty marveled, “has flowing glaciers on it.”

The last of the Pluto data from New Horizons arrived on Earth back in October, but the mission isn’t over. The probe is headed out for a look at the Kuiper Belt object 2014 MU69, at which it will arrive on January 1, 2019.

Beatty said this great new data about Pluto was worth the wait.

“We finally know what this planet/dwarf planet/interesting world looks like,” he said. “It was a 30-year effort from the time the Pluto missions were first conceived until we finally got out there. Some of the people involved, like Alan Stern, were there every year of the way, and boy, what a rich reward they have for their efforts.”


Start saving: flying to space with Blue Origin

If there’s any anti-science sentiment around these parts it wasn’t evident last Friday at Peddler Brewing Company in Ballard, where some 500 space enthusiasts packed the brewer’s beer garden—yes, we were sitting outside, in Seattle, in January—to hear from employees of Kent-based Blue Origin about the company’s latest testing and the prospects for an affordable ride to space any time soon. The event was the latest installment of Astronomy on Tap Seattle, organized by graduate students in astronomy at the University of Washington.

Blue Origin Folks

L-R Nicholas Patrick, Dan Kuchan, and Sarah Knights of Blue Origin after their presentation at Peddler Brewing Company. Astronomy on Tap photo: Brett Morris and Nicole Sanchez.

“Our ultimate mission is to have millions of people living and working in space,” said Sarah Knights, outreach coordinator at Blue Origin. “The way that we’re focused on that is to lower the cost of human spaceflight, and one of the ways to do that is to make vehicles reusable, so that’s our primary focus right now.”

Blue Origin’s current test vehicle is the New Shepard, a capsule and vertical takeoff/vertical landing rocket. It’s powered by the BE-3, for Blue Engine 3, which is fueled by liquid oxygen and liquid hydrogen and can deliver 110,000 pounds at full thrust. As suggested, the rocket blasts off, and then lands softly back on Earth.

“As it’s coming back down we can throttle it back to about twenty percent of its full throttle, so that means that as the propulsion module is coming down we can have an equal thrust-to-weight ratio, find the landing pad, and very gently set it down,” Knights explained.

Blue Origin safety test

Dan Kuchan, Product Development Team lead engineer on the New Glenn program at Blue Origin, said the most recent test of New Shepard, conducted in October, was of the vehicle’s full-envelope crew escape system.

“That means that if the rocket at some point decides that we can’t go to space today, the crew capsule can jettison itself and get out of Dodge,” Kuchan explained. It was the first such in-flight escape test for a space vehicle since 1965, during the Apollo program. Kuchan showed this video of the flight test during the presentation.

“That was an awesome test and it capped off the fifth flight and landing for that booster,” Kuchan said. “The system worked flawlessly.”

Astronauts soon

So far New Shepard has only flown without a crew, but they hope to have astronauts on board soon. That’s where Nicholas Patrick comes in. Patrick, a former NASA astronaut who flew on space shuttle missions for construction of the International Space Station, is now Blue Origin’s human integration architect.

“I’m responsible for worrying constantly about every aspect of flying on our spacecraft,” Patrick said. That includes everything from meeting rules and regulations, testing to make everything right, and every imaginable human factor.

They chose a capsule rather than a winged vehicle like the space shuttle partly for safety. The smaller capsule can get away from the booster quickly, as demonstrated in the video above. Patrick said it’s also a better way to travel.

“For those who are paying to ride aboard a New Shepard in the coming years this is a more authentic rocket flight experience than most other ways you could get to space,” he said.

The New Shepard capsule has big windows, the largest ever flown in space, and all passengers will have one of their own; there are no middle seats on New Shepard. Suborbital flights will last about eleven minutes, and passengers will be weightless for several minutes.

“We want to give them the best imaginable experience,” Patrick said. He showed this video animation of what a New Shepard flight will be like.

“That’s a New Shepard flight that we hope will be available to anybody who can get in and out of the capsule, who can tolerate the three Gs on ascent, and a little higher on descent,” Patrick said. “So start saving.”

At what cost?

How much to save is a question that Patrick said hasn’t yet been answered.

“Obviously everybody’s goal is to get this price down a long way,” he said. “We’re not going to get millions of people living and working in space by charging a quarter of a million or a hundred thousand dollars just for a suborbital flight.”

The question of when people will fly on New Shepard also hasn’t been answered.

“We’re not driven by that kind of schedule,” Patrick said. “We’re driven by our flight test program and the success or challenges we face in each of those tests.”

“What I can tell you is that I expect we’ll be flying people in the next year or two,” he added.

Kuchan noted that, in a way, New Shepard astronauts will be human guinea pigs.

“New Shepard and everything we’re doing, sending tourists into space, is all a way for us to practice and master landing a reusable rocket, and using it in a commercially viable way, so that over the next 50, 100, 200 years we can move civilization deeper into space,” Kuchan said.

Next steps: a bigger rocket

Blue Origin’s motto is gradatim ferociter—step by step, ferociously. The next step for the company is on the drawing board now: the New Glenn, which will get payloads into Earth orbit. The New Glenn will dwarf the New Shepard. While the latter is powered by one BE-3 engine that delivers 110,000 pounds of thrust, the New Glenn will have seven BE-4 engines that deliver 550,000 pounds of thrust each. That’s a lot of oomph. Again, there’s no totally firm timeline, but Kuchan said they’ve been asked to deliver the rocket by the end of the decade, and added that they plan to do so. It’s another step on the way to having millions of people living and working in space.

“Every single decision that gets made at Blue Origin is weighed against that ultimate goal,” Knights said.


Do not miss this! Tyler Nordgren and solar eclipses

Tyler Nordgren wants to make sure that what happened to him as a nine-year-old astronomy nut doesn’t happen to you this summer.

Tyler Nordgren

Tyler Nordgren reads an excerpt from his book Sun Moon Earth during a presentation January 14, 2017 at Town Hall Seattle. Photo: Greg Scheiderer.

Nordgren, a professor of physics at the University of Redlands and author of Sun Moon Earth: The History of Solar Eclipses From Omens of Doom to Einstein and Exoplanets (Basic Books, 2016), talked at Town Hall Seattle earlier this month about the book and his work to educate the public about the total solar eclipse that will cross the United States on August 21, 2017.

As a kid Nordgren was passionate about astronomy and already knew he wanted to be an astronaut. He was living in Portland, Oregon in 1979 when a total solar eclipse passed right over his house.

“Because of the news warning us about looking at the Sun, I was sure that if I accidentally looked at the Sun during the eclipse, there were these special rays that would come out and burn my eyes,” he recalled. “So I hid in the house with the curtains drawn and I watched it on TV.”

He could tell the eclipse was happening because the house got really dark, but that was his one and only take-away from the event.

“One of the things that has driven me to work on this and to help promote this eclipse that is coming up this year is I don’t want to see another nine-year-old child out there having the experience that I did!” Nordgren said.

Good things come to those who wait

“It took me twenty years to eventually, finally see (a total solar eclipse) for myself,” Nordgren noted. He described what it’s like, the things that happen approaching and during totality, but said that he had an unexpected reaction to that first totality.

“As an astronomer, I know the mechanics of the celestial alignment, yet in this moment of totality, I fully understand the difference between knowledge and feeling,” he said. “When I finally, after 20 years, got a chance to see this for myself as a professional astronomer south of Budapest in Hungary in 1999, I swear the hair stood up on the back of my neck. It still remains the most amazing thing I have ever seen in the sky.”

“I could understand why generations of human beings would cower in fear at this,” he added, “and wonder, ‘When is the life-giving Sun going to come back?’”

Eclipse science

Nordgren described some of the stories different cultures cooked up to explain eclipses, and also discussed some of the science done during eclipses, including the determination, from spectra, that the Sun was largely made of hydrogen and contained some iron. Helium was discovered on the Sun 25 years before it was found on Earth. Perhaps the most famous science made possible by an eclipse was the determination that mass can indeed bend light waves, as predicted by Einstein’s theory of general relativity and measured during a solar eclipse in 1919. The media coverage turned Einstein from an obscure physicist into an icon.

“This is what made Einstein Einstein in the popular culture,” Nordgren said.

Do not miss this!

This August’s total solar eclipse will be the first to cross the United States from coast to coast since 1918. Nordgren, also an artist, has designed travel posters for many of the spots along the path of totality, and shared them as he talked about the path the eclipse will take. You can see, and buy, them on his website.

He pointed out that virtually everyone in the country will be able to see some degree of partial solar eclipse, but he urged us all not to settle and stay home just because there might be traffic.

“Do not miss this!” Nordgren urged.

“The difference between being inside and outside that path of totality is literally the difference between night and day,” he noted. “Inside totality, the sky goes black, the Sun turns dark, the stars come out, the corona is visible. Outside totality, yeah, it kinda gets sorta dark. Yeah, use your glasses. Yeah, there’s a bite taken out of the Sun. But it will pale in comparison to what you experience—not just what you see, but what you feel inside that path of totality.”

Nordgren said a good solar eclipse may be just the thing that we need.

“In difficult times, when, heaven knows, there have been lots of things that do not unite us, here is going to be a moment in which we are all united under the shadow of the Moon, and we will all be seeing this together,” he said. “This will become the most photographed, the most Tweeted, the most Instagrammed, the most shared group moment in the history of the world.”

“That’s what we have to look forward to this summer,” he concluded.

Further reading: Also check out our review of Sun Moon Earth, posted in December, and our article about Nordgren’s keynote address at the Seattle Astronomical Society annual banquet in 2014.


Grinspoon: Earth in human hands

David Grinspoon himself wonders how an astrobiologist wound up writing a book about the human impact on Earth. Grinspoon, author of Earth in Human Hands: Shaping Our Planet’s Future (Grand Central Publishing, 2016), answered the question during a Science in the City lecture recently at Pacific Science Center.

David Grinspoon

Astrobiologist and author David Grinspoon talked about his new book, Earth in Human Hands, January 10 at the Pacific Science Center. Photo: Greg Scheiderer.

“I am struck by the unique strangeness of the present moment,” Grinspoon said, noting that we are at the controls, if not actually in control, as we enter a new epoch in human history. Some find the proposed name of Anthropocene—the age of humanity—a touch self-centered or self-aggrandizing, but Grinspoon feels it is a fitting moniker.

“It represents a recognizable turning point in geological history brought about by one species: anthropos,” he said. “Our growing acknowledgement of this inflection point can be a turning point in our ability to respond to the changes we’ve set in motion.”

In fact, Grinspoon finds it promising that there’s some recognition that we the people are a major factor in what is happening.

“We need to learn all that we can about how planets work so we can make the transition from inadvertently messing with Earth to thoughtfully, artfully, and constructively engaging with its great systems,” he said.

A long history of planetary change

Grinspoon noted that it’s always fruitful to take a close look at the long-term history of Earth.

“We are not the first species to come along and radically change the planet and cause problems for the rest of the biosphere,” he said. In fact, the first one was not nearly so clever as we are. About 2.5 billion years ago the humble cyanobacteria caused a terrible calamity.

“They transformed the planet, the most radical chemical transformation that our planet has ever experienced,” Grinspoon explained. “They flooded the atmosphere with a poison gas that spelled certain doom for most of the other species that were living on the planet at that time.”

What they learned to do was photosynthesis, and the poison gas they spewed was oxygen. The oxygen also destroyed much of the warming methane in the atmosphere of the time, which led to a global glaciation that turned Earth into a giant snowball, a condition that lasted until volcanoes pumped out enough carbon dioxide to warm the planet up again.

“Cyanobacteria presumably never discussed that fact that they were starting to ruin the world,” Grinspoon quipped.

Four types of change

Grinspoon identifies four broad types of planetary change:

  • Random
  • Biological
  • Inadvertent
  • Intentional

The classic example of the random is an asteroid strike, something that just happens that there’s little control over. The cyanobacteria fall under the biological change. We’re in the midst of great inadvertent change right now, with automobiles, population growth and other factors driving a spike in carbon dioxide levels that began in the 1950s.

We’ve barely dipped our toes into the intentional. Grinspoon explained that our first stab at intentional change came with regard to fixing the hole in Earth’s ozone layer. The solution came from scientists studying Venus and trying to explain the planet’s lack of oxygen. They realized that chlorine destroys oxygen and ozone. Other scientists connected the dots and concluded that chlorofluorocarbons in refrigerants, propellants, and other products on Earth were eating away at our planet’s ozone layer.

Fixing the ozone

Interestingly, Grinspoon noted that this created an argument that may sound familiar. Some called the notion a hoax, there were attempts to discredit it, opposing “science” was created, and there was lengthy debate.

“The truth won out,” Grinspoon said. A global agreement was reached: the Montreal Protocol. Alternate chemicals were developed that didn’t deplete the ozone. Grinspoon said it’s working.

“It’s still going to be another fifty years or so because it takes time for the ozone layer to come back,” he said. “The natural chemical reactions that re-create ozone take fifty to one hundred years.”

“Assuming we stay on track, this is actually a success story, and it’s an existence proof that this kind of global change is possible,” Grinspoon added. “Not that it’s easy, and there are some ways in which fixing global warming will be inherently harder than this, but it shows that we are capable of a different approach.”

Thinking long term

While global warming is an important challenge, Grinspoon said it is a relatively short-term one, and that we need to think even further down the road. He said such random events as asteroid strikes don’t have to happen.

“We have a space program; the dinosaurs didn’t, and look what happened to them!” he quipped. We know how to identify possible threats and have a pretty good idea about what to do when they occur.

Further, Grinspoon said that we have an illusion that climate is always more-or-less fine, only because we’ve been lucky enough to live in a time of relative stability. We need to think about the next ice age, which he said will eventually occur.

“If we get over the near-term climate harm that we’re doing, we will have the knowledge that will allow us, when the need arises—we’re talking 10,000 or maybe even as much as 50,000 years in the future—we’ll have the ability to interrupt that cycle of ice ages and preserve the relatively benign climate, not just for ourselves but for other species as well,” Grinspoon said.

Who is out there?

All of this allowed Grinspoon to put on his astrobiologist hat and talk a little about the search for extra-terrestrial intelligence (SETI).

“When you do the math of SETI what you realize is that the question of is there anybody out there to talk to comes down to the question of longevity,” he said. “You can show this mathematically, that if civilizations last for a long time—that is, if this problem is soluble of how to create a stable technological civilization and use technology in the service of survival rather than self destruction—if that’s possible to do and if it happens on other planets, then there ought to be other civilizations out there that we could discover and maybe even communicate with.”

Thus the Anthropocene epoch represents something of a turning point. There are those who regard it as doom and gloom, as something we can’t beat, but Grinspoon doesn’t see it that way.

“The true Anthropocene is something that should be welcomed,” he said. “Though it is yet only in its infancy, it can be glimpsed. Don’t fear it; learn to shape it.”

“It is the awareness of ourselves as geological change agents that, once propagated and integrated, will provide us with the capacity to avoid doom and take our future into our own hands,” Grinspoon concluded.

Books by David Grinspoon:


LIGO and the era of multimessenger astronomy

Multimessenger astronomy is a fairly new buzz word in the science. Dr. Joey Key, an assistant professor of physics at the University of Washington Bothell and a member of the LIGO Scientific Collaboration, talked about the concept at last month’s meeting of the Seattle Astronomical Society.

Joey Key

Dr. Joey Key of the UW Bothell gave a talk about LIGO and the era of multimessenger astronomy at the Dec. 21 meeting of the Seattle Astronomical Society. Key made the same presentation to the Everett Astronomical Society Jan. 7. Photo: Greg Scheiderer.

As you probably know LIGO—the Laser Interferometer Gravitational-wave Observatory—made the first detection of gravitational waves, as predicted by Einstein’s theory of general relativity, back in December 2015 and announced the findings last February. So now what?

“The next big goal for LIGO is to have a gravitational wave detection where we also get an electromagnetic signal from the same source,” Key explained. She noted that various wavelengths of light, from gamma ray to radio, require different types of tools to detect and reveal different things about objects observed. Key said gravitational-wave astronomers refer to such science as “electromagnetic astronomy.” The big hope, then, is to learn even more if there can be an electromagnetic observation as well as a gravitational wave observation of the same event.

“That’s what we would call a multimessgenger source,” Key said.

A difficult search

Einstein never thought gravitational waves could be detected because he figured they would be too small. It took a century of technological advances to prove him right—again. Finding a multimessenger source may be an even more elusive needle in the cosmic haystack.

Key explained that, right now, it’s hard for LIGO to detect with precision from whence a source signal originates. When they detect a source they send an alert to about 60 electromagnetic astronomy partners and give them a general direction in which to look. In addition to the challenge of pinpointing the source, they also don’t really know what to look for. Key said their models aren’t very good, not yet anyway. Light from a source may have already passed, but there could be x-rays, gamma rays, afterglow, or shock waves under certain conditions.

Fortunately, LIGO is getting better. The addition of more Earth-based observatories will help better locate sources and discover collisions of neutron stars or stellar-mass black holes. Project LISA, scheduled to launch in 2029, will look for supermassive black hole collisions and “extreme mass ratio in-spirals” which occur when a little star or black hole falls into a big black hole. Pulsar timing arrays could detect when supermassive black holes collide in galaxy mergers. There’s even study of the cosmic microwave background to try to detect gravitational waves from early universe.

“Just like electromagnetic astronomy, different sources are detected by these different kinds of experiments,” Key said. “We need all these different kinds of gravitational-wave experiments to be able to study the gravitational-wave sky.”

The LIGO Scientific Collaboration includes more than a thousand scientists from 15 countries and 90 institutions. Four of the institutions are in Washington: The University of Washington, UW Bothell, Whitman College, and Bellevue College.

Unknown discoveries ahead

Key said it is an interesting time to be involved in the field as LIGO is just into its second observing run.

“We’re really going to be able to map out and explore the population of black holes in our universe,” Key said.

“We don’t know what we’ll discover, and that is always the story of a new astronomy,” she added. ”We do not know very much about black holes in general, and so this is a new way to study the universe and study what is out there. It will be very exciting!”

LIGO could discover new kinds of sources like cosmic strings, study supernovae, and maybe even lead to the detection of dark matter and dark energy.

“We are lucky we live in the era of gravitational-wave astronomy, and we hope soon that it will be the era of multimessenger astronomy,” Key concluded.


SU Search for Meaning Fest includes three talks with astronomy themes

If you’re looking for meaning you may be able to get some clues in February at Seattle University. The university’s annual Search for Meaning Festival is set for February 25, 2017, and will bring more than 50 authors and artists to campus to tackle topics surrounding the human quest for meaning and the characteristics of an ethical and well-lived life. Three of these talks may be of particular interest to astronomy enthusiasts.

ShetterlyMargot Lee Shetterly, author of Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race (William Morrow, 2016) will give a keynote talk at the festival about race, gender, science, the history of technology, and much else. She will show us the surprising ways that women and people of color have contributed to American innovation while pursuing the American Dream. Hidden Figures has been made into a feature film that opens in theaters in January.

Marie BenedictMarie Benedict, author of The Other Einstein (Sourcebooks Landmark, 2016) will talk about her novel and explore the life of Mileva Maric, who was Albert Einstein’s first wife and a physicist herself, and about the manner in which personal tragedy inspired Mileva’s possible role in the creation of Einstein’s “miracle year” theories. She’ll also discuss how Mileva’s story is, in many ways, the story of many intelligent, educated women whose own aspirations and contributions were marginalized, or even hidden, in favor of those of their spouses.

CoyneRev. George V. Coyne, SJ, former director of the Vatican Observatory and currently the endowed McDevitt Chair in Physics at Le Moyne College in Syracuse, New York, is author of Wayfarers in the Cosmos: The Human Quest for Meaning (Crossroad, 2002). Father Coyne will talk about the history of the evolution of life in the cosmos—a history which may lead us to a deeper understanding of what many secular physicists say themselves about the cosmos: that a loving creator stands behind it.

The full schedule for the daylong event is available online. General admission tickets are $12.50 and are also available online.

Get the books in advance:

Purchases made through links on Seattle Astronomy help our efforts to bring you interesting space and astronomy stories. We thank you for your support.


Dava Sobel and the ladies of the Harvard Observatory

If you don’t know the names Williamena Fleming, Antonia Maury, Henrietta Leavitt, Cecilia Payne, and Annie Jump Cannon, you’re not alone. Many people working in astronomy don’t recognize these women who have made enormous contributions to the field.

Dava Sobel

Dava Sobel talked about her new book “The Glass Universe” Dec. 15 at Town Hall Seattle. Photo: Greg Scheiderer.

“They’re making a splash now,” laughed Dava Sobel, author of the new book The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars (Viking, 2016). Sobel talked about the book Thursday night at Town Hall Seattle.

There is an impression that the women who worked at the observatory were trivialized or marginalized, Sobel said that really wasn’t the case.

“They really were well treated, they were given this tremendous responsibility, they made valuable discoveries, and they were well regarded—and some of them even world famous—in their own lifetimes,” Sobel said. She pointed out that Cannon, for example, held a number of honorary degrees, was a member and officer of the American Astronomical Society, and also was an honorary foreign member of the Royal Astronomical Society.

Interestingly enough, even Sobel, whose bailiwick is science history, hadn’t heard of Leavitt until her name came up during an interview for a magazine article she was writing 20 years ago. Her curiosity was piqued, and the seed for The Glass Universe was planted.

Cheap labor

Sobel noted that when Edward Pickering took over as director of the observatory in 1877 there were already a half a dozen women working there, many of them relatives of the resident astronomers. He liked working with the women. They did good work, and they were inexpensive.

“Women cost less,” Sobel said. “This is an old story about women earning less than men for doing the same work.”

But she added that it wasn’t just dollars and cents for Pickering.

“He was very open minded, broad minded, and felt that higher education for women was a good thing even at a time when this was questioned,” Sobel said. “There were people who really thought that college was bad for girls and could affect their ability to have children.”

Pickering recruited alumnae of women’s colleges who studied astronomy, asking them to make observations and contribute their data to the work of the observatory.

“That would be a way to prove to the world that women could make a contribution to science and that their education wasn’t wasted,” Sobel said.

Financial support from women

The observatory was a separate entity and didn’t receive any money from Harvard. Much of the work at the observatory was possible due to significant financial support from women.

Heiress Anna Palmer Draper and her husband, Dr. Henry Draper, had done some of the earliest work on photographing the spectra of stars. Henry Draper was a medical doctor, but he was, according to Sobel, a passionately engaged and inventive amateur astronomer. They built their own observatory and Henry created many of his own instruments for the work on spectra. Unfortunately, Henry got sick and died at the age of 45. Anna eventually donated much of their gear, and a lot of money, to the observatory to continue the work on stellar spectra.

Philanthropist Catherine Wolfe Bruce donated $50,000 to help the observatory set up a telescope in Peru for observing the skies of the southern hemisphere. Data from this instrument informed Leavitt’s work on variable stars.

Major achievements

The contributions by the computers were significant. A few examples noted by Sobel:

Leavitt studied variable stars and discovered that the brightest ones took longer to cycle through their changes, and that the length of the cycle correlated to the true brightness of the star. Knowing this, one can calculate how far away a variable star is based on how bright it appears from Earth.

Harvard women 1918

Some suggest this 1918 photo of Harvard College Observatory women in “paper doll” pose marginalizes them, but Sobel says they were regarded and treated well in their time. Photo: Harvard University Archives.

“This work was fundamental to distance measurements all over the sky,” Sobel said. The discovery, most often called the period-luminosity relation, is more often these days being referred to as “Leavitt’s Law.”

Cannon, a renowned observer, came up with the star classification system still in use today.

Fleming first came to the observatory as a maid, but later found astronomical success, too.

“She was the first woman to get a university title at Harvard,” Sobel said. “She was the curator of astronomical photographs.” Her analysis of some ten thousand stars were critical to the publication of the first Henry Draper Catalogue.

Maury, Draper’s niece, studied at Vassar, graduated with honors in astronomy and physics, and went to work at the observatory, where she came up with a system of identifying stars.

Payne was Harvard’s first Ph.D. in astronomy. It was no surprise that a woman earned the top degree first; all of the early graduate students in astronomy were women because the only money the observatory had for the graduate program came through fellowships established for women to study there. Payne studied spectra of stars and found that hydrogen was far more prevalent in stars than any other element. She wrote about her findings in her dissertation, but it was so counterintuitive that it was downplayed. Within a few years, however, her findings were confirmed.

Given the stature of the accomplishments, it seems astounding that these women are not more well known.

“A lot of history gets buried just because there are so many people, so many characters, so much time goes by,” Sobel noted, adding that the women didn’t feel marginalized at the time. “They really loved what they did and were credited for it, but over time I think it has been downplayed.”

They’re making a splash now

There’s been a lot more attention for the women astronomers in recent years. A decade ago George Johnson penned the biography Miss Leavitt’s Stars (W.W. Norton and Company, 2006). A couple of plays have been written about them, including Silent Sky by Laruen Gunderson, which was produced earlier this year in Seattle by Taproot Theatre. You can go back to read our coverage of the play. The 2014 reboot of the television series Cosmos with Neil deGrasse Tyson featured a segment about the computers.

“This got the attention of a lot of young women,” Sobel said. The Harvard women are also featured in the web series Insignificant.

“It’s great fun to see their story being remembered in so many ways. There are even Lego figures,” of Cannon, Leavitt, and Payne, Sobel said. “You know you’ve made it!”

Several other recent books have highlighted the work of women in space and astronomy. Sobel singled out The Rise of the Rocket Girls (Little, Brown and Company, 2016) by Nathalia Holt, a story about the women who made contributions to space science at the NASA Jet Propulsion Lab; and Hidden Figures (William Morrow, 2016) by Margot Lee Shetterly, a look at the African-American women who worked at Langley in the 1940s and ‘50s. Hidden Figures has been made into a feature film that is scheduled to open in theaters in January.

An important story for our times

Sobel said she enjoyed getting to know the personalities of the ladies of the Harvard College Observatory and feels that their story is an important one in the era of fake news and anti-science attitudes.

“All of us need to be telling true stories about science,” Sobel said. “I feel especially good about this one not only because it’s true, but because I hope it will be inspirational to young women to have models like these ladies and to show that women have always been interested in science.”

More books by Dava Sobel:

Purchases made through links on Seattle Astronomy help cover our costs of bringing you interesting space and astronomy stories. We thank you for your support!