Category Archives: lectures

Seeing the invisible and finding aliens using polarimetry

The topic line for last week’s gathering of Astronomy on Tap Seattle was What the Hell is Polarimetry?, and it seemed that a significant portion of the audience at Peddler Brewing Company in Ballard shared the question.

UW postdocs Jamie Lomax and Kim Bott explained that when light starts from its source the oscillation of its wave—its “wiggle”—goes in all directions until an interaction with something makes it polarized.

“That just means that it’s wiggling in one direction,” Lomax noted. “There’s a preferred plane for that wiggle to happen in, and in polarimetry what we’re doing is measuring that preferred plane and we’re looking for light that has been polarized.”

“It can help you figure out the shape of things without having to resolve the object,” Bott added.

Polarimetry and massive stars

Lomax studies massive stars and has found use for polarimetry in her work. She gave a talk titled, “Seeing Invisible Circumstellar Structures.”

Jamie Lomax

Jamie Lomax

“The holy grail for us in massive star research is to be able to take a massive star at the beginning of its lifetime, figure out how massive it is,” Lomax said, “and map out what its life is going to look like and figure out what supernova it’s going to end its life as.”

“It turns out that is really hard, and it’s complicated by the fact that most massive stars are probably in binary systems,” she added. Since about two-thirds of massive stars are part of a binary system, one might expect that two-thirds of core-collapse supernovae would be from such systems.

“There’s a problem, and that is we’ve only seen maybe two or three core-collapse supernovae where we have evidence that suggests that it’s come from a binary star,” Lomax said.

Part of the problem, she said, is that we don’t yet know enough about the evolution of binary star systems.

“We can try to hammer out the details of how that mass is transferring between the two stars and when the system is losing material to try to figure out how that effects its future evolution,” Lomax said. “Once we start answering questions like that we can start to tease out why we aren’t seeing all of these binary supernovae we think we should be seeing.”

Lomax talked about the star Beta Lyrae, a binary system. The primary star in the system is losing mass that gets gobbled up by the secondary. This transfer of mass also forms a thick accretion disk of gas around the secondary—so thick light from the actual star can’t get through. There’s also evidence that there are jets shooting out of the system, but we don’t know where they are.

“These are all features that we can’t see very well,” Lomax said. “We can’t see the mass transfer stream between the two stars, we can’t see the jets.”

Here’s where polarimetry comes in. If a star is surrounded by a cloud of gas or dust that is circularly symmetrical, when the starlight interacts with that material the light becomes polarized, and the wiggles line up tangentially with the edge of the disk. If the cloud is elongated in some way, the wiggles form in a “preferred” direction.

“That preferred wiggle direction is 90 degrees from the direction of the elongation of the disk, so you can back out geometric information pretty quickly,” Lomax said. “Just by looking at how the light is wiggling I can tell you how the disc is oriented on the sky.”

Lomax figures that if you don’t do polarimetry you’re throwing out free information.

“You can see invisible things—to you—and that gives you extra information about what’s going on in different systems.”

Exoplanets and aliens

Bott’s talk was titled “The Polarizing Topics of Aliens and Habitable Planets.” She studies exoplanets and said polarimetry comes in handy.

“Stars don’t produce polarized light, which is really great if you’re trying to look at something dim like a planet,” she noted. The polarimeter will simply block out the starlight. There are then a number of things that might be spotted on the planet:

  • Glint from an ocean
  • Rayleigh scattering
  • Clouds and hazes
  • Rainbows
  • Biosignatures of gases in an atmosphere
  • Chiromolecules
Kim Bott

Kim Bott

These can help astronomers characterize a planet, judge its potential habitability, and even determine if life might already be flourishing there.

Bott said that polarimeters that are sensitive enough to study planets are a recent advance, and they’re studying big, bright planets to get the hang of it. Looking for rainbows can be revealing about liquids in the atmosphere of a planet.

“The light will bend in the droplets at a slightly different angle depending what the droplet is made out of,” Bott said, so they can tell whether its water, methane, or sulfuric acid.

“We’re trying to create these really robust models that will take into consideration polarized light from Rayleigh scattering in the atmosphere as well as from rainbows,” Bott said, “and if you have a planet where you can see the surface you’d be able to see the signature from glint as well.”

Since different substances bend light at different angles, we can also learn a lot by watching closely as planets move through their phases as they orbit their host stars.

“On Earth we have light going from air and bouncing off of H2O water,” Bott said. “That’s going to produce a maximum in polarized light at a different angle than on, say, Titan, where you have light going from a methane atmosphere and then bouncing off of a hydrocarbon ocean.”

“We can actually, in theory, tell what the ocean and atmosphere are made out of by looking at where, exactly, in the orbit we see this glint,” Bott explained.

As for aliens, life requires more complex molecules, chiromolecules, that are “wound” in a certain direction, like our own DNA. Such molecules would produce circularly polarized light, which if detected could be a sign that such molecules exist on the planet.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. It’s next gathering is scheduled for October 30 at Peddler Brewing Company in Ballard.

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Calendar: Orbit around October

A month of space and astronomy events are on the calendar at the Museum of Flight, with three events kicking it all off this week.

Orbit Around October

Orbit Around OctoberThe museum’s space month is dubbed Orbit Around October, with new events on Saturdays during the month.

It all starts off on October 5 with Astronomy Night during the museum’s monthly Free First Thursday. There’s no admission charge between 5 p.m. and 9 p.m. Area astronomy clubs will be on hand with telescopes and information, and there will be other educational activities throughout the evening.

The museum also offers a couple of events on Saturday, October 7. A 2 p.m. presentation called “21st Century Communities in Space: The Cultural Details in Living Away From Earth” will celebrate the 60th anniversary of Sputnik, and then look forward to the future when we’ve colonized the Moon and Mars and are creating communities in space. What sort of culture will be there?

Then at 5:30 p.m. join in on a reception, lecture, and book signing with space writer Leonard David. David’s book Mars: Our Future on the Red Planet (National Geographic, 2016) is a companion to the recent Mars miniseries produced by the National Geographic Channel. Tickets to this event are $25, $20 for museum members, and must be purchased online by October 3.

Haunted Night Sky

The Pierce College Science Dome brings back the popular planetarium show Haunted Night Sky on Saturdays during October. The show, geared for kids aged 3-12, guides viewers to use their imaginations to find creatures in the night sky, build a Frankenstein satellite, and take a tour of the Sea of Serpents on the Moon, the Witch’s Head nebula, and other spooky places in the universe. Showtimes are 12:30 p.m. and 2 p.m. each Saturday, and it runs about 45 minutes. Tickets are $6 for kids—adults are free—and are available in advance online.

Astronomy clubs

A quick rundown of the regional astronomy club meetings this week:

Mark your calendar

You can scout out future astronomy events by visiting our calendar page.


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Calendar: What the heck is polarimetry?

The monthly gathering of Astronomy on Tap Seattle and a variety of star parties highlight this week’s calendar.

AOT

AOT Sept 27My Webster’s Ninth New Collegiate Dictionary defines polarimeter as “an instrument for determining the amount of polarization of light or the proportion of polarized light in a partially polarized ray.” I still don’t know what that means or why astronomers might be into polarimetry, but we’ll find out at 8 p.m. Wednesday, September 27 when Astronomy on Tap Seattle meets at Peddler Brewing Company in Ballard.

The guest speakers are both UW postdocs: Dr. Jamie Lomax will discuss her research using polarimetry to detect the almost-invisible material around stars, and Dr. Kim Bott will explain how she uses polarimetry to hunt for signs of habitable worlds.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. The evening’s festivities include astronomy-themed trivia and fabulous prizes. It’s free, but buy beer. Bring your own chair to create custom front-row seating.

Star parties

Several star parties are on the calendar for the weekend. The Covington Community Park Star Party is scheduled for 9 p.m. Friday, September 29 at the park. The party is sponsored by Covington Parks and Recreation with support from the Seattle, Tacoma, and Boeing Employees astronomical societies.

The Seattle Astronomical Society plans its free monthly public star parties for 8 p.m. Saturday, September 30 at two locations: Green Lake in Seattle and Paramount Park in Shoreline.

Planetarium

The WSU Planetarium in Pullman offers a new program this weekend, “Astronomy 101.” The show runs at 7 p.m. Friday, September 29 and repeats at 5 p.m. Sunday, October 1. Tickets are $5 at the door, cash or check; no credit cards.

Mark your calendar

The Museum of Flight will observe Astronomy Night next Thursday, October 5 beginning at 5 p.m. Astronomy clubs from the area will be on hand with telescopes and information. It’s part of the museum’s free first Thursday offerings.

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Learning about exoplanets with AoT Seattle

Often when an exoplanet is discovered the first question asked by the mainstream media is whether the new planet is “Earth-like.” In truth we know little about these far-away planets other than their mass or size, and whether they orbit within the habitable zone of their host star. Scientists are using PCA and SAMURAI to learn more about exoplanets, and LUVOIR may ultimately help us get a much better look at these distant worlds.

Tovar

Lupita Tovar spoke about mapping exoplanets at Astronomy on Tap Seattle August 23, 2017. (Photo: Greg Scheiderer)

Lupita Tovar is a first-year Ph.D. student in astronomy and astrobiology at the University of Washington, where she works at the Virtual Planetary Laboratory. She gave a talk titled “Mapping New Worlds” at the most recent Astronomy on Tap Seattle event at Peddler Brewing Company in Ballard. Tovar is helping develop the parameters for LUVOIR, which stands for Large UltraViolet/Optical/InfraRed Surveyor. It is one of four projects being considered by NASA as part of the 2020 decadal survey, which will help pick the agency’s next big project.

Big is the operative word for LUVOIR. Astronomers love aperture for their telescopes, and LUVOIR would dwarf any space telescope to date. The Hubble Space Telescope has a 2.4-meter mirror, and the James Webb Space Telescope, scheduled for launch next year, will be 6.5 meters. LUVOIR would nearly double that; Tovar said it is proposed right now to have a 12-meter mirror. It would also be equipped with a coronagraph which would block the light of a host star. Much as Venus and Mars were visible in the daytime during last month’s total solar eclipse, blocking starlight would allow us to see much dimmer objects nearby.

LUVOIR

Sketch of LUVOIR by NASA/Goddard

“The coronagraph will allow us to see those close-in planets, like Venus, and allow us to study those planets,” Tovar said. LUVOIR would be a powerful instrument. It could see Venus, Earth, and Jupiter from a distance of ten parsecs, or about 33 light years.

Fortunately, astronomers don’t have to wait for LUVOIR to make progress on mapping exoplanets. Tovar said that today they’re using PCA—Principal Component Analysis—to get a better idea about an exoplanet’s surface.

“We use PCA to extract how many components are there,” Tovar explained. “Is it just one, solid icy body? Are there two different types of surfaces sitting on that planet? Are there three? Are there more? PCA allows us to extract that information.”

Call in the SAMURAI

Once they know how many surface types there are, astronomers can then use SAMURAI—Surface Albedo Mapping Using RotAtional Inversion—to figure out just what those surfaces are. Tovar said it’s like looking at a beach ball as it is batted around. As the ball spins, different colors face the observer. SAMURAI uses algorithms to determine the composition of each surface type. For example, land reflects more light than ocean does, but an ocean’s reflection will spike when it’s near the edge of the exoplanet, from our view, because of the glint of light from the host star.

LUVOIR is just a glint in the eyes of astronomers now, but it along with PCA and SAMURAI could give us a much better idea about the makeup of exoplanets.

“Combined together, all of these three components will help you create a map,” Tovar said.

Is Tatooine out there?

Star Wars fans often speculate about the existence of planets like Luke Skywalker’s home world Tatooine, which has two suns. So far we know of a dozen exoplanets in orbit around binary star systems. Diana Windemuth, also a Ph.D. student in astronomy and astrobiology at UW, studies these sorts of systems and gave a talk titled, “By the Light of Two Suns” at Astronomy on Tap Seattle.

Windemuth

Diana Windemuth discussed exoplanets orbiting binary star systems at AoT Seattle. (Photo: Greg Scheiderer)

“Our Sun is a bit of a weirdo in that it does not have a companion,” Windemuth said, explaining that about half of stars like the Sun have one. The more massive a primary star is, the more likely it is to have a companion, she said. Further, there are two types of stable orbits a planet in a binary star system can have. In an S-type orbit the planet will go around just one of the stars; it will be either a circumprimary or circumsecondary orbit. In the P-type, the exoplanet orbits both stars.

“A circumbinary planet goes around in a wider orbit around an inner, closer-in binary,” Windemuth explained. She said it is harder to find these sorts of systems using Kepler’s transit method because throwing in a third body complicates things. Kepler measures the overall light from a system, and the amount of light we see changes not only when the planet transits, but when the stars eclipse each other.

“These are called eclipsing binaries because they go around one another,” Windemuth said. Exoplanets are confirmed when dips in the light during transits happen at regular intervals. Usually a computer picks that out of the data, but it doesn’t work so well on binary systems.

It’s a trick!

“It turns out its difficult to train a computer to do that because of what we call the geometric effect,” Windemuth said. Because the stars move with respect to each other in binary systems, the period of transits can appear to vary because of differing distances the light travels to reach us. Gravitational interactions in the system can also create wobble and change the perceived period of transits.

“Even though the period of your planet might be the same, the transits will occur at different times,” Windemuth noted.

It’s probably because of these challenges that we’ve only discovered a handful of circumbinary planets so far, Windemuth said, and none of them are candidates to be the real-life Tatooine.

“No terrestrial circumbinary planets have been found yet,” she said. That could be because they’re too hard to find, or maybe planets with short periods are destroyed when they orbit too close to the binary stars.

“It’s probably because our detection algorithms are not good enough yet,” Windemuth concluded.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. The next gathering is scheduled for September 27 at Peddler Brewing Company in Ballard, and the topic will be polarimetry. We don’t know what that is, either, but are looking forward to finding out!

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Making beer and weighing stars

Science these days is often all about interdisciplinary work. It’s seldom just biology or just geology, and so it wasn’t surprising that the most recent gathering of Astronomy on Tap Seattle had a heavy dose of chemistry. It was for a good cause, though, as Trevor Dorn-Wallenstein, a second-year graduate student in the University of Washington Astronomy Department, gave a talk titled “An Unbeerlievable Tale” explaining how the universe made us beer, and a glass to put it into. The event happened July 26 at Peddler Brewing Company in Ballard.

It turns out you only need five elements for beer:

  • hydrogen
  • nitrogen
  • carbon
  • oxygen
  • phosphorous
Trevor Dorn-Wallenstein

Trevor Dorn-Wallenstein talks about celestial beermaking at Astronomy on Tap Seattle July 26, 2017 at Peddler Brewing Company in Ballard. (Photo: Greg Scheiderer)

We had the hydrogen about a millionth of a second after the Big Bang.

“It’s not until 10 seconds after the big bang that we can smoosh a proton and a neutron together and have deuterium and have that deuterium last,” Dorn-Wallenstein said. “Once we have that deuterium though, we’re off to the races.”

If you add a proton to the deuterium you make helium 3, or add a neutron and make tritium. Add the missing nucleon to either and you’ve got helium 4. It’s not in beer, but we’ll need it later. Much later. We have to wait about 1.5 million years, until stars start to form and start fusing new elements. Stars about two times the mass of our Sun can fuse hydrogen into helium, then toward the end of their life cylcles do what Dorn-Wallenstein called the “triple alpha reaction.” They smash three helium atoms into carbon, and add another helium nucleus to make oxygen. When the star reaches its red giant phase these elements blow off with the stellar wind.

“We’ve pollulted the interstellar medium with hydrogen, with carbon, with oxygen,” Dorn-Wallenstein said, “three of the things we need to make beer.”

Higher-mass stars, say ten times the mass of the Sun, can fuse things such as neon, titanium, silicon, sulfur, magnesium, aluminum, and calcium.

“It can unlock all of these additional stages of nuclear fusion,” Dorn-Wallenstein said.

Nickel beer night

The process leaves behind a stellar core of nickel 56 which decays into iron 56.

“Iron 56 is the end of the line for a star,” Dorn-Wallenstein explained. “There is no physical way to get energy out of an iron 56 nucleus. You cant fuse it with something else, you can’t fission it and turn it into two more things, you get nothing out of this nucleus. That’s a problem for a star.”

The outer part of the star collapses onto the core and explodes into supernova, blasting all of the elements it has made out into the interstellar medium.

“The environment around this supernova explosion is so energetic that you can make pretty much anything you want,” Dorn-Wallenstein said. “Pick any element in the periodic table that’s heavier than iron—it’s probably made in a supernova.”

Nitrogen is conspicuously missing from the list, and it is kind of hard to make. Dorn-Wallenstein said we get a little bit, but not enough, from supernovae or at the end of a smaller star’s life.

“The only way to produce enough nitrogen is via this thing called the carbon-nitrogen-oxygen, or CNO, cycle,” he said, explaining that this is how stars produce helium from hydrogen. Since nitrogen takes longer, it builds up in stars. In the universe at large there are about four or five carbon atoms for every nitrogen atom, but in a star that’s doing the CNO cycle there are more than a hundred times more nitrogen atoms than carbon.

“Via this process of converting hydrogen into helium, we actually make nitrogen as a by-product,” Dorn-Wallenstein said.

The beer glass

We’ve got the ingredients for beer. Where do we put it?

“It turns out the most complicated thing that goes into a beer is the glass itself,” Dorn-Wallenstein said, noting that your mug is mostly silicon dioxide, with a bit of sodium oxide, aluminum oxide, calcium oxide, and trace amounts of potassium, magnesium, iron, titanium, and sulfur. All of that stuff came out of a supernovae.

We have all we need for beer. Now we just need a planet to form, simple life forms like yeast to emerge, wheat and hops to grow, and someone to mix it all into a barrel and let it sit for a while.

“Look at that; we’ve made beer,” Dorn-Wallenstein concluded.

Weighing stars

The second talk of the evening at Astronomy on Tap Seattle was given by Dr. Meredith Rawls, who spoke about “Weighing Stars with Starquakes.” Rawls employs asteroseismology—your word of the day!—to figure out the mass of stars.

Rawls

Dr. Meredith Rawls discussed a new method for determining the masses of stars at Astronomy on Tap Seattle. (Photo: Greg Scheiderer)

Rawls noted that one way to calculate the mass of a star is to observe binary systems. We can measure the blockage of light as the stars orbit each other, and the Doppler shift that occurs when they do. Combine those two measurements and you get a reliable measure of the stars’ masses.

The drawbacks, according to Rawls, are that not all stars are part of binary systems, and that this method is slow and uses a lot of limited telescope time. Rawls gets around this by using asteroseismology, measuring the oscillations, or starquakes, that occur in a star’s interior. They actually ring like a bell, though you can’t hear it because space is a vacuum, and the frequency is too low in any case. Like a bell, the more massive the star, the lower the frequency of the oscillation. You can’t see the oscillations because they’re inside the star, but they change the star’s brightness. This is something that can be observed, and astronomers chart brightness changes against the frequencies of the starquakes and see how they line up with other properties of the star.

“You fit a bunch of curves to a bunch of wiggles and you try to convince yourself you’re not making it up,” Rawls quipped. The method can give clues about a star’s surface gravity, density, and temperature, and with gravity and density you can calculate mass.

Does it really work?

Rawls said they like to study red giant stars for a couple of reasons: that’s the eventual state of our Sun, and red giants brighter and easier to see. After figuring masses of many red giants with asteroseismology, they went back and calculated them again using the binary method. Then they compared the two.

“Oh, crap!” was Rawls’s reaction upon seeing how they matched up. “It’s not one-to-one. I broke science!”

In fact, the masses calculated through asteroseismology differed from those returned by the binary method by about 16 percent, on average. It turns out that big, red giant stars are not quite so simply just huge versions of our Sun.

“They have their own weird convection stuff going on,” Rawls explained. “There’s different stuff happening in different layers of the star that isn’t quite the same as what happens inside our Sun, and it’s just complicated enough that you can’t compare them one to one, even though it would be super handy if you could.”

What do they do to reconcile the differences between the two methods?

“We have to apply empirical corrections in order to get accurate masses,” Rawls explained. In other words, “We have to fudge it a little bit! But it’s consistent. It’s fine, it’s fine. Totally works. Not a problem. Don’t worry about it,” she laughed, adding that asteroseismology works just great for smaller stars like the Sun.

“It’s actually really useful, even though sometimes it doesn’t always work perfectly, because you can measure a lot of stars’ masses really fast,” she concluded.

Astronomy on Tap Seattle is organized by graduate students in astronomy from the University of Washington.


Some photos from recent Astronomy on Tap gatherings, and videos of the July talks:

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Solar eclipses and the stature of science

A total solar eclipse that crossed the American West in 1878 helped ignite a great boom in science in the United States. David Baron is hoping that, in an era in which people have to march in the streets in support of science, the total solar eclipse that will cross the nation next month will be similarly inspirational. Baron, a former science editor for National Public Radio, is the author of American Eclipse: A Nation’s Epic Race to Catch the Shadow of the Moon and Win the Glory of the World (Liveright, 2017). He spoke about the book last week at the Pacific Science Center, part of the center’s Science in the City lecture series.

Baron saw his first total solar eclipse from Aruba in 1998.

“I was just dumbfounded,” he said at the sight of the eclipse, which revealed stars in the daytime and Jupiter, Mercury, and Venus. “There, among the planets was this thing; this glorious, bewildering thing. It looked liked a wreath woven from silvery thread and it just hung out there in space, shimmering.”

It was the Sun’s corona, and Baron said the photos you’ve seen don’t do it justice. Soon, the eclipse was over.

“The world returned to normal, but I had changed,” Baron said. “That’s how I became an eclipse chaser.”

He said he decided that day, on the beach in Aruba, that he wanted to write a book about solar eclipses. He also figured 2017 would be the year to release it, with public interest in solar eclipses likely to be at its apex because of this year’s eclipse. So his book has been 19 years in the making. He said the work started in earnest about seven years ago, when he went researching for interesting eclipse stories to tell.

The American eclipse of 1878

Battle Lake markerBaron came upon a historical marker next to Battle Lake in the Wyoming Sierras, which claims that Thomas Edison came up with the idea to use bamboo as a filament for an electric light bulb while fishing at the lake in 1878. Baron found no evidence that this was actually true, but Edison was involved in eclipse watching in Wyoming that summer, for the total solar eclipse of July 29, 1878. The eclipse ran from Montana south down across the American frontier through Texas. At the time, Baron noted, Europeans were the clear leaders in eclipse science.

“Here was America’s chance to shine—or an opportunity to slip up and embarrass ourselves—but if all went well we would show the rest of the world what we were capable of as a scientific nation,” Baron said, “and so the eclipse was a big, national undertaking.” The eclipse and the expeditions to observe it received in-depth coverage in the newspapers.

Edison was among a group that went to Rawlins, Wyoming to view the eclipse. The group included Norman Lockyer, who had discovered helium on the Sun and founded the journal Nature; and James Craig Watson, an astronomer at the University of Michigan, who was in search of the hypothetical planet Vulcan that could explain orbital anomalies of Mercury.

David Baron

Author David Baron spoke about his book American Eclipse on July 19, 2017 at the Pacific Science Center. (Photo: Greg Scheiderer)

Also out west was Maria Mitchell, professor and director of the Vassar College Observatory, who brought a group of Vassar students to Denver to show that women could do science, too. For Edison’s part, he was anxious to test an invention he called the tasimeter, intended to detect minuscule changes in temperature. Astronomers were interested in the device, which might reveal if the Sun’s corona gave off heat.

“These three main characters of mine had a lot on the line,” Baron said, and on the day of the eclipse they declared great success and the press was highly positive, though neither Edison, Watson, nor Mitchell really achieved their set goals.

“Maria Mitchell did help open the doors of science and higher education to women, but it’s not like male scientists suddenly embraced their female counterparts,” Baron noted. “It was the beginning of a long, hard, continuing struggle.”

Watson didn’t find Vulcan, of course; the precession of Mercury’s orbit was explained later through Einstein’s general relativity. Edison’s tasimeter never lived up to the hype. He did head home and start work on the light bulb, though not in the way the Historical Landmark Commission of Wyoming would have you believe.

“The eclipse of 1878 did not illuminate America in the way the historical marker claims,” Baron said. “However it did enlighten America, helping to push this upstart nation toward what it soon would become—the undeniable global superpower in science, a country that would, in this intellectual realm, eclipse the world.”

Learning from history

Baron sees an interesting parallel with next month’s total solar eclipse.

“Once again the Moon’s shadow will visit us at an interesting time in our intellectual development,” he noted. “Today the issue isn’t whether America can rise up and take on the world in science, the question is whether America can maintain its global lead.”

It will undoubtedly be the most widely viewed total solar eclipse in human history. We’ll see whether it has the power to change hearts, minds, and the course of history.


You can purchase American Eclipse though the link above or by clicking the image of the book cover. Purchases made through links on Seattle Astronomy support our ability to bring you interesting astronomy stories. Thank you!

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Astronomy on Tap plus Nordgren eclipse talk highlight week’s events

Another episode of Astronomy on Tap Seattle is on the calendar for this week, and astronomer, artist, and author Tyler Nordgren will visit the Museum of Flight to talk about his latest book about total solar eclipses.

The whole premise of Astronomy on Tap is that astronomy is even better with beer. This month we go even one step further, learning how beer isn’t possible without science as we go “From Stars to Beer.” The gathering will be at 8 p.m. Wednesday, July 26 at Peddler Brewing Company in Ballard.

AoT co-host Trevor Dorn-Wallenstein will give a talk titled, “An Unbeerlievable Tale: How atoms come together in stars to make the most glorious structure in the low-redshift universe: beer.” That may be the longest subtitle ever, too! Dr. Meredith Rawls will discuss her research about “Weighing Stars with Starquakes” with a fantastic technique called asteroseismology.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. It’s free, but buy beer. Bring your own chair to create premium front-row seating in Peddler’s outdoor beer garden.

Nordgren on Eclipses

We’ve covered a number of talks by Tyler Nordgren over the last several years. Nordgren, astronomy professor at the University of Redlands, is also an author, artist, dark-sky advocate, and entertaining presenter. He’ll be at the Museum of Flight at 2 p.m. Saturday, July 29 to talk about his latest book, Sun Moon Earth: The History of Solar Eclipses (Basic Books, 2016).

The book is part travelogue covering some of Nordgren’s recent eclipse-chasing adventures, part history of eclipses and the myths and science surrounding them, and part primer for the total solar eclipse that will be visible from the United States next month. It’s a marvelous volume and we recommend it highly.

Nordgren spoke about the book at Town Hall Seattle back in January. You can read our re-cap of that talk and our review of the book. Nordgren will sign copies of Sun Moon Earth following his talk Saturday. Grab the book by clicking the book cover or link above; it helps Seattle Astronomy exist!

Star parties galore

The Seattle Astronomical Society will be involved in three star parties this weekend. The Covington Community Park star party will be held at 10 p.m. Friday, July 28 in said park. Volunteers from the Boeing and Tacoma societies also help out with this event.

SAS will hold its free monthly public star parties at 9 p.m. Saturday, July 29 at two locations: Green Lake in Seattle and Paramount Park in Shoreline. Bad weather cancels these star parties, so watch the SAS website or social media for updates. But hey, we’re on a good-weather roll!

Jazz Under the Stars

Jazz Under the StarsThe Tacoma Astronomical Society and Pacific Lutheran University physics department will lead stargazing at PLU’s Keck Observatory on Thursday, July 27 following the PLU Jazz Under the Stars concert. The artist for the free concert, which begins at 7 p.m. in the outdoor amphitheater of the Mary Baker Russell Music Center at PLU, is Anjali Natarajan, a Brazilian jazz vocalist out of Olympia. If the weather is bad the stargazing may be off, but the concert will just move indoors.

Jazz Under the Stars concerts will also be held on the next two Thursdays, August 3 and 10.


 

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