Finding life

A trio of scientists from the University of Washington took the audience on a search for life on other planets during a recent Science in the City talk at Pacific Science Center.

Professor Erika Harnett opened the evening explaining the overall work of NASA’s Virtual Planetary Laboratory, which is headquartered at the UW.

Erika Harnett
Photo: Greg Scheiderer

“We use a variety of techniques to study planets found in our solar system and in other solar systems for their potential habitability, the potential for life developing there,” Harnett explained.

Harnett’s particular research interest is on the vanishing atmosphere of Mars. Rovers there have helped us confirm that, while the Red Planet is now cold and arid, it was once warm and had oceans and flowing rivers. It also once had a global magnetic field, but it doesn’t any more.

“At some point in Mars’s history—and we’re really having a hard time telling when—its global magnetic field disappeared, and at that point its atmosphere was fully exposed to the radiation of space,” Harnett said. “Probably at that point it started losing a large amount of its atmosphere to space and that’s when water stopped becoming stable.”

There’s lots of ice at the poles and underground on Mars, but if warmed it would go straight to vapor because of the low atmospheric pressure.

Harnett and others are working to figure out the time line for if and when Mars was habitable.

Space is big

While we’ve been to Mars robotically and may well go in person one day, Harnett noted that space is big and there aren’t that many other places to go where life might be possible. For the rest of the universe we use remote sensing.

“We train telescopes looking at a variety of wavelengths at those locations and try to see what kind of information we can read from those wavelengths of light,” she said.

We can figure out a lot even from a little bit of light. Aliens looking at Earth from afar might conclude that the blue light means lots of water. They could measure our rotation by tracking light changes. Green or brown light might mean vegetation while white would be an indicator of ice. We could use similar methods learn such things about exoplanets far away.

Life on Jupiter’s moons

Marshall “Moosh” Styczinski is a UW graduate student who said he first got interested in Jupiter after watching the movie 2001: A Space Odyssey. Jupiter is still his favorite planet.

Moosh Styczinski
Photo: Greg Scheiderer

“Its got these four big moons that are a great place to start looking if we want to find life elsewhere in the solar system,” Styczinski said. The focus is on Europa, but the other Galilean moons play a part as well.

“Io plays a surprisingly big role in both why Europa is a promising place to look, and how we study it,” Styczinski noted. Io is pockmarked with volcanoes and its surface is coated with sulfur spewed from those volcanoes. The moons are heated internally because of tidal heating and orbital heating, and not just on the rocky moons.

“Tidal heating causes friction in the interior that warms up the rocks and melts the ice from the underside,” Styczinski explained. “The ice forms a thick crust on top that acts like a blanket, keeping the water warm from the cold space outside.”

Life needs more than just water. Europa also probably has nutrients because liquid water comes into contact with hot rocks.

“Hydrothermal vents are what makes Europa an exciting place to look for life,” Styczinski said. “It has all the basic ingredients that life needs: an energy source, nutrients, water, and shelter.”

We’ve learned a lot about Europa and made models based on our observations so far, but we need more data to get a better handle on questions like the inner structure of this moon, how deep the water is, and where geysers and hydrothermal vents might be found. The Galileo probe is no more, but a couple of other missions are on the drawing boards. NASA plans to launch the Europa Clipper some time in the next decade, and the European Space Agency is scheduled to launch JUICE—Jupiter Icy Moons Explorer—in 2022.

“Both of these missions are going to visit Europa many times, and return lots of valuable measurements that can help refine our models,” Styczinski said. “Finding the right model for Europa’s interior can directly guide future missions by telling them where to go and what we might find when we get there.”

Analyzing exoplanets

We know for certain of some 2,500 exoplanets—planets orbiting stars other than our own Sun—and there are about five thousand more possibles, of which UW grad student Brett Morris, a co-founder of Astronomy on Tap Seattle, expects about 95 percent will also be confirmed as planets. Most of these have been discovered by the Kepler telescope observing a dip in the light when an exoplanet transits in front of its host star. Morris said this discovery is not really so tricky as it sounds.

Brett Morris
Photo: Greg Scheiderer

“Probably even your iPhone camera is good enough to measure the change in brightness of the Sun when something goes in front of it,” he said. “If you just measure the brightness of the star instead of actually resolving the surface and seeing things going on, you can discover planets.”

Morris said that for every exoplanet the size of Jupiter, they’re discovering two that are about the size of Neptune and a dozen that are roughly the size of Earth.

“The big surprise is that the most common type of world is one that we don’t know anything about,” Morris said. A great many exoplanets have been discovered that are somewhere between the size of Earth and Neptune, which is about four times the diameter of the home planet. Since we don’t have any of these “mystery worlds” of that size in our solar system, the first thing astronomers want to figure out is at what size point these planets are more likely to be gaseous than rocky.

“Exactly where that line is will determine how much habitable real estate there is in the universe,” Morris said, as we don’t expect anyone or anything to be living on gas planets.

Morris is looking forward to the launch of the James Webb Space Telescope, now scheduled for next year. JWST will see in infrared, and will examine spectra of light from the atmospheres of exoplanets to reveal the elements that exist there.

“What we hope to look for are oddballs,” Morris said. Earth, for example, is the oddball of our solar system. While Venus and Mars have atmospheres of mainly carbon dioxide, ours is rich with nitrogen, oxygen, and a host of trace elements.

“Life is what causes the atmosphere here to be different,” Morris said. “We might have trouble saying whether or not life is to blame if we were looking at planets in other solar systems, but we could definitely flag that one and then try to study it harder, because something interesting is going on there.”

After the talks we watched the 3-D movie The Search for Life in Space. The film is visually spectacular. One often had the notion that a moon or the Cassini spacecraft were about to land in the next seat. It’s worth a look if you get a chance. It’s showing at Pacific Science Center at least through January. Check out the trailer below.

Merging neutron stars and cool galaxies at Astronomy on Tap Seattle

One of the cool things about the Astronomy on Tap Seattle series of talks in pubs is access to scientists who are working on headline news. It happened at their October gathering at Peddler Brewing Company in Ballard. Jennifer Sobeck, a stellar astrophysicist in the Department of Astronomy at the University of Washington, was all set to give a talk titled, “A Hitchhiker’s Guide to the Galaxy: Bumming Around the Milky Way.” But a few days before the talk the news hit that LIGO and others had detected gravitational waves generated by merging neutron stars. Neutron stars are Sobeck’s thing, so the script went out the window and we learned about what happened.

Sobeck noted that neutron stars are what’s left behind when high-mass stars—around four to eight times the mass of the Sun—blow up in a supernova. Neutron stars are incredibly dense; the mass of the Sun packed into something 12 miles across. They have a crust, though light still gets through.
“Inside is just basically a soup,” Sobeck said. “It’s a hot mess.”

Everything inside is so compressed that scientists call it “degenerate.”

“There are no more atoms, there are no more molecules, those are all blown apart,” Sobeck explained. “It’s just like a soup of neutrons; there are just tons of neutrons, and the really cool thing is down in the center, they think the pressures are so high that you actually might get quarks.”

August discovery

Scientists knew they had detected a neutron star merger rather than the sort of black-hole mergers previously spotted by LIGO because the signals are different. The interesting thing about the detection of two neutron stars merging is that we could see it visually because the event created a kilonova, like a supernova, but smaller.

“It’s a little bit less on the explosion scale,” Sobeck said. “Kilonova means that you’re able to have electromagnetic radiation across the spectrum that a whole bunch of facilites were able to monitor.”

So when LIGO and VIRGO detected the gravitational wave, with the help of the Fermi gamma ray space telescope and the ESA’s Integral gamma-ray observatory they they were able to narrow down the location of the event and tell others to look there. When the optical observations came in, the kilanova was spotted in the galaxy NGC 4993.

“This has never been done before,” Sobeck noted. The detection occurred in mid-August of this year, and by the end of the month the visual was gone.

“This kilonova explostion lasted only for a period of only 15 days,” Sobeck said.

Observations were made not just in the visual, but across the spectrum from gamma rays to radio, and more than a dozen observatories were involved in the analysis.

“You’re getting a different piece of information from all of these parts of the spectrum,” Sobeck noted. “They all helped fill in that puzzle.”

The story in the media

Sobeck said the press went a little overboard with headlines such as collision “creates gold” (CNN)  and “Universe-shaking announcement” (New York Times), yet it’s true that the kilonova made some gold. Sobeck noted that hydrogen, helium, and a bit of lithium came from the Big Bang, but the rest of the elements were made in stars. But stars can only fuse elements as heavy as iron. To get the really heavy stuff called lanthanides you need a kilanova. The emitted light tells you what’s there. If you see blue light after a kilonova, that means there’s a high concentration of silver, cadmium, and tin. If the light is more red, then platinum, gold, mercury, or lead is present.

“This particular event went from blue very, very, quickly to red, and it stayed red most of the time,” Sobeck said. “Hence, we’ve got a bunch of gold on our hands.”

“We found out that neutron-star mergers do make elements,” she said. “We were right, so huzzah!”

All kinds of galaxies

Grace Telford, a graduate student studying astronomy and data science at the UW, stuck with her original topic of “A Whirlwind Tour of Galaxies: the Tiny, the Gigantic, and Everything in Between” for the October Astronomy on Tap. She noted that there are several ways to classify galaxies:

• Stellar mass or brightness
• Shape
• Star formation rate
• Nuclear activity

Stellar mass or brightness

This is pretty straightforward.

“Basically the more stars a galaxy has, the brighter it is,” Telford noted. There’s quite a range of sizes. The Milky Way is a pretty common-sized galaxy, and it’s hard to make them bigger. The largest are around 10 times the size of the Milky Way.” Smaller galaxies are plentiful.

“A dwarf galaxy is something that is at least a hundred times less massive than our Milky Way,” Telford said, and they can go a lot smaller.

Way out at the small end of the chart are ultra faint dwarf galaxies, which can’t really be seen because they’re too faint. They can’t be detected at long distances.

A recently discovered type is called an ultra diffuse galaxy. This may be the same size as the Milky Way but have 100 times fewer stars, all held together by dark matter.

“This is an open area of research,” Telford said. “It’s hard to explain how to form these wierdo galaxies that are not very massive at all, but huge.”

Shape

The three main shapes of galaxies are elliptical, spiral, and irregular. Spirals may come with a large central bulge or a bar. Irregular galaxies tend to be small.

Star formation rate

It’s in star formation rate that galaxies really differentiate themselves, Telford said. Galaxies that emit a lot of blue light have lots of young stars and new star formation. Galaxies that look red are “quenched.” Their stars are older, and there’s little new star formation.

In between red and blue is the “green valley” of galaxies. They don’t actually emit green light, but they’re in transition from blue to red.

An interesting type is the “starburst” galaxy. These are galaxies that somehow stumble into a source of gas that wasn’t available to them before.

“They have the ability to form stars at a very high rate relative to the normal amount of star formation for a galaxy of its size,” Telford explained. “As a result, you have a lot of these massive young stars that are dying and exploding as supernovae and injecting a lot of energy into the gas.”

These objects are short-lived, they exhaust their gas in a hurry, at least in astronomical terms—in between 100 million years and a billion years.

Nuclear activity

Most galaxies have supermassive black holes, which can create jets of energy.

“Sometimes these black holes eat a lot of gas really quickly and then they blow out a whole bunch of energy,” Telford explained. These jets are nuclear activity. Galaxies with active galactic nuclei are most typically found in the green valley, though they’re in other types as well.

Telford gave a plug for Galaxy Zoo, where you can go looking for these differing types of galaxies and actually participate in citizen science.

Visiting Vesta and Ceres

The Dawn spacecraft has found a lot of surprises at Vesta and Ceres. Debra Buczkowski
a geologist and planetary scientist at the Johns Hopkins University Applied Physics Lab, gave a talk recently at the Museum of Flight discussing some of the findings from the mission.

Dr. Debra Buczkowski, a geologist
and planetary scientist at the Johns
 Hopkins University Applied Physics
Lab, spoke about the findings of the
Dawn mission to Vesta and Ceres
recently at the Museum of Flight.
(Photo: Greg Scheiderer)

Vesta was Dawn’s first stop, entering orbit around the asteroid on July 15, 2011. Scientists expected to find volcanoes on Vesta. Buczkowski explained that this expectation traces back to meteorites found on Earth that are know to be from Vesta. These are known as HEDs: “howardite–eucrite–diogenite.” These closely resemble igneous rocks found on Earth, and those are made from volcanic activity. But the volcanoes aren’t there.

Before Dawn arrived at Vesta the Hubble Space Telescope showed that Vesta wasn’t spherical, but rather was significantly flattened out at its south pole. Scientists speculated that this was because of an enormous impact, and that proved to be correct. Dawn observed a huge impact crater, now called Rheasilvia Basin, the rim of which is almost as wide as Vesta itself.

“It really should have broken the asteroid apart,” Buczkowski said of the impact that created the basin, which has a huge central peak. Dawn also found a second impact crater, Veneneia Basin, which is almost as large.

Another surprise finding from Dawn is that Vesta is fully differentiated.

“Most of the asteroids are just kind of chunks of rock with one kind of rock all the way through,” Buczkowski explained. “Not Vesta; Vesta actually has a core, it has a mantle, and it has a crust.”
Vesta’s core is about half the diameter of the asteroid itself, about 220 kilometers.

“This is probably why Vesta did not fall apart when the Rheasilvia Basin formed, because it has this huge, massive core,” Buczkowski said.

The surface of Vesta was found to have lots of fractures, features larger that Earth’s Grand Canyon that look like faults. Buczkowski said they did a lot of computer modeling to see if an object the size of Vesta with a core the size of Vesta’s could develop fractures on the crust.

“The stresses that result from that huge impact kind of get redistributed because of the giant core,” she said of the findings. “Instead of being focused around the crater, they move to the equator and fracture at the equator. If we do this same model without the giant core, there’s no fracturing at the equator. So it’s because of the giant core that we have these huge fractures.”

Buczkowski said that was a little disappointing because they were hoping for volcanoes or magma-driven geology. While they didn’t find volcanoes, there is evidence of moving magma that didn’t break through to the surface. Rather, it pushed some of the surface upward, forming mounds.

On to Ceres

Dawn departed Vesta in September 2012 after spending about 14 months in orbit. As Dawn approached the dwarf planet Ceres there was much speculation about extremely bright spots on its surface that were found in Hubble images. Other observations had detected water vapor on Ceres. Since Ceres is relatively large but not dense, scientists were expecting to find ice. But there was more rock and less ice than anticipated. What they did find, Buczkowski said, was evidence of volcanism.

This image from NASA’s Dawn spacecraft shows Occator Crater
on Ceres, with its signature bright areas. Dawn scientists have
found that the central bright spot, which harbors the brightest
material on Ceres, contains a variety of salts. (Image
 credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

“We’re not expecting magma on Ceres,” she said. “Ceres isn’t dense enough for the kind of magma that we’re used to here on Earth, made out of silicate rocks. This is something called cryomagma; it is basically ice with a little bit of rock.”

The biggest and brightest of the bright spots, named Cerealia Facula, is in the crater Occator. Many of the craters on Ceres are fractured, even on the crater floors, and the many bright spots on Ceres are associated with these fractures.

“What it’s looking like is that we’re having cryomagmatic activity underneath (Occator) crater,” Buczkowski said, “and what’s coming up out of these fractures is a pyroclastic spray, and the water, the volatiles in that, is sublimating away and all it’s leaving is the sodium carbonates.” Those are the bright spots we see all over Ceres.

Dawn also found that Ceres is covered in ammoniated phyllosilicates.

“Ammonia is interesting,” Buczkowski explained. “We don’t expect to find ammonia this close to the Sun, it’s usually something that’s found further out in the solar system.” They’re still studying whether Ceres may have formed further from the Sun and migrated in, or if the ammonia somehow made its way to Ceres from the outer solar system.

It turns out that Ceres had quite a few volcanoes, though most of them have now collapsed. There’s one that hasn’t, known as Ahuna Mons, that stands about five kilometers tall. It’s a cryovolcano.

“The volcano that we thought would be on Vesta is on Ceres,” Buczkowski noted. Ahuna Mons may be younger than the others, and also may collapse over time.

Like Vesta, Ceres was found to be differentiated, though only partially so.

“There’s a rocky core, there’s a volatile-rich mantle, and there’s a muddy slurry, a mud ocean” below the crust, Buczkowski said.

Ceres is now considered a dwarf planet, while Vesta still has asteroid status because of its lopsided shape from the giant impact. Buczkowski figures Vesta deserves dwarf-planet status, too. Whatever you call them, she thinks they’re fascinating to study because they’re kind of a bridge between the asteroids and rocky planets.

“These are more involved bodies than just plain, old asteroids,” Buczkowski said. “They’re not just chunks of rock floating in space. They’re actually like little mini-planets. They’ve got a lot of planet-like properties.”

Though they’re pretty small, they can teach us a lot.

“They’re interesting to us because they tell us a lot about how Earth and the other planets formed,” Buczkowski said. “Studying these little protoplanets we actually are looking back to the beginning of the solar system.”

APOD: more than just pretty pictures

The Astronomy Picture of the Day is more than just a pretty photo. In fact, each of the featured images may well have more than a thousand words packed into it. You just need to drill down deeper into the site.

John McLaren, a NASA Solar System Ambassador and treasurer of the Seattle Astronomical Society, gave a presentation about APOD at the society’s meeting last week. He said the key to finding a wealth of information about celestial objects is dragging your eyes away from the pretty pictures long enough to notice the explanation of the photo and, more importantly, the submenu below it. McLaren uses this information when preparing presentations about astronomy for various groups.

“You can build a more complete story,” he explained. “There are good links here for education, for outreach, and home-schooling groups.”

You’ve probably noticed that the explanations of the photos use plenty of links to further information. Below the explanation there’s typically a set of “more on” links about objects or content. The real prize, though is in the index, a fully searchable listing of what’s on the APOD site.

That’s a lot of stuff. McLaren noted that the site was started by Robert Nemiroff and Jerry Bonnell when both worked at the Goddard Space Flight Center. The first posts were in June of 1995, and there have been more than eight thousand of them since. McLaren pointed out that when you look at the site, it is very 1995. There’s no flash or fancy moving menus. It’s pretty straight HTML, and the authors figured that changing things would run the risk of breaking a zillion links to APOD information.

The Earth from Apollo 17

Picture Credit: NASA, Apollo 17, NSSDC

They don’t update the photos published, either. Clicking on each photo gives you the best version of it that they have. The one at left, a photo of Earth taken from Apollo 17 in 1972, was posted in the first week of APOD’s operation. When McLaren showed this photo on the big screen during his presentation, there was some laughter about its low resolution. He reminded us that in 1995 we were probably dialing in to the Internet with a 2400 baud modem, and that wouldn’t deliver the high-res goods in the manner to which we’ve become accustomed in our broadband world.

Click the “archive” link on each page and you’ll find a long scroll, day by day, of every APOD ever. The “index” link takes you to a menu of stars, galaxies, and nebulae, solar system objects, space technology, people, and the sky. Clicking on these will give you a handful of “editors’ choice” photos they consider to be the most educational on the chosen subject.

McLaren found this photo, the APOD of October 20, 2002, of the space shuttle docked with the Russian Mir space station in 1995. It made him wonder who took it. Was it the first known selfie?

The Space Shuttle Docked with Mir. Credit: Nikolai Budarin,
Russian Space Research Institute, NASA

“Since it was the first docking, they wanted to get good information about how the two spacecraft functioned together,” McLaren explained. “So one of the Soyuz crews on Mir actually undocked their Soyuz spacecraft, did a fly-around, and observed the combination.” All of that was found by following the links on the photo page.

Astrophotographers who aspire to be published on APOD may well wish to check out its index of Messier objects. McLaren points out that many of the objects in the index are represented by numbers, not pictures.

“They don’t have photos of all the Messier objects posted yet, so if you submit a good color picture of them you may get your photo as the astronomy photo of the day,” he noted, which could lead to fame and fortune or at least bragging rights.

The search engine for the index is useful. Type in “Saturn rings” and it will find 200 items.

“There’s a wealth of information in there if you’re looking for something,” McLaren said.

So the next time you’re checking out the Astronomy Picture of the Day, remember that there’s a whole lot of knowledge lurking beneath those gorgeous photos.

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

Jamie Lomax

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

“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

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.

Treknology looks at Star Trek gizmos

Star Trek first hit the airwaves over a half century ago, and Dr. Ethan Siegel finds it amazing how many of the gizmos, gadgets, and technologies imagined by the various Trek television series have become reality. Siegel, theoretical astrophysicist and science writer, is author of the new book Treknology: The Science of Star Trek from Tricorders to Warp Drive (Voyageur Press, 2017). Treknology is scheduled for release on October 15 and is available for pre-order on Amazon now.

Siegel, a Trek fan since discovering The Next Generation (TNG) as a kid, figures he was just the guy to dig into Star Trek’s technology.

“That intersection of an interest in Star Trek and Sci-fi, of an interest in what it means for humanity, and a knowledge of physics, all of those have come together to make this book possible,” Siegel said.

Treknology devotes a separate chapter to 28 different technologies that were used in the various series.

“These technologies that were so futuristic that they were imagined centuries in the future, some of them don’t appear to be that far off,” Siegel noted. “Some of them are already here and in widespread use. Others that we thought just a few years ago were going to be far-future technologies look like they’re coming to fruition.”

We’ve got that Treknology already

Siegel noted that it was The Original Series (TOS) that came up with the automatic sliding door, now a staple in every airport and supermarket. Your tablet is also cooler than anything Trek came up with.

“What you’ve got in your smart phone is much more impressive that anything that were on those touch-screen pads that Star Trek envisioned,” Siegel said. “Here we are with something that’s smaller, that’s more compact.”

That goes for pretty much all of the computers, he noted.

“We’ve gone way beyond what Star Trek would have envisioned much more quickly than anything that came about in the original series,” Siegel said. At the time of TOS in real life we had room-sized computers that had less computing oomph than today’s pocket calculators. When TNG came around, they figured they had to jazz up the computing and came up with something new and fancy—digital storage.

“Your flash drive is more powerful than a Star Trek isolinear chip,” Siegel noted. “As far as computation goes—ships computer, pads, isolinear chips—we’ve blown away what Star Trek would have envisioned.”

Medical technology

Dr. Ethan Siegel, author of Treknology,
during a lecture in Portland last year.
Photo: Greg Scheiderer.

As an astronomy and physics guy, Siegel said he was especially interested in learning about the medical technologies and biological situations that Star Trek dreamed up. He noted that we may soon be able to use synthehol, a substance with the positive effects of booze without the negative impacts.

“Synthehol is on track pharmacologically to become real,” Siegel said.

We may also be close to helping sightless people see, ala Geordi La Forge—the TNG character played by LeVar Burton—who wore a special visor that allowed him to see the entire electromagnetic spectrum.

“If we can make an implant somewhere in your brain’s visual cortex, and we can wirelessly feed an external signal to that implant,” Siegel said, “this is a potential way to restore sight to the blind,” even if they have no eyes or optic nerves at all. NASA actually tinkered with sight-improving technology in the late 1990s, and called its project JORDY: Joint Optical Reflective DisplaY.

Not there yet

There are other Treknologies that aren’t so close yet. Warp drive is at the top of that list. He says it’s mathematically possible, but it will be tough to make it work in our universe.

“It depends on if you can either have negative gravitational mass or negative energy,” Siegel explained. “If you can, then great, we can build warp drive. If that’s a physical impossibility—and we haven’t discovered anything like that yet—then I don’t know how warp drive can be possible.”

“This is probably one of the most difficult technologies to achieve, but I still don’t want to rule it out and say it’s impossible,” he added. “I want to look at what it would take to make it possible.”

A few other technologies such as subspace communication and transporters would require “extensions” to our current physics to become reality, Siegel said, and we’re a ways from life-like androids and holodecks, too.

Siegel has written widely. His first book was Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific Publishing Co., 2015). He writes the Starts With a Bang blog on Forbes, and produces a podcast of the same name. Siegel can be found under that handle on Twitter and Facebook. He expects to be touring conventions and bookstores around the country in support of Treknology. We look forward to the book’s release next month.

Planning for the 2024 total solar eclipse

Last month’s total solar eclipse was the first one I had ever seen. Like many newly minted and experienced umbraphiles alike, I’m already thinking about the next total solar eclipse to cross the United States, which will happen on April 8, 2024. It seems like a long time off, but you don’t want to be like those folks who were frantically looking for eclipse glasses the day before the event!

As I ponder the last two years of planning for 2017, I realize that the advice received in the course of the enterprise was somewhat contradictory. In summary, when preparing for a total solar eclipse, one should plan carefully and well in advance, always have a plan B, and be ready to chuck it all and just wing it in the case of bad weather or other opportunities and circumstances.

Plan ahead

Fred Espenak
Photo: Greg Scheiderer

Our first tutorial in eclipse planning came from Mr. Eclipse himself, Fred Espenak, who spoke at the Seattle Astronomical Society banquet in January 2016. (Here’s our recap of that talk.) Espenak and his weather guru partner, Jay Anderson of Eclipsophile, scouted the entire path of totality for viewing and weather conditions. It was Espenak’s declaration of Madras, Oregon as having the best clear-sky prospects for eclipse day that drove thousands of people to central Oregon. My favorite remark from Espenak from that talk: “On eclipse day you don’t get climate, you get weather.”

Oregon had the best odds, many of us rolled the dice on that and came out winners.

Have a plan B

For many eclipse chasers plan B amounts to watching the weather forecast in the days and weeks leading up to the eclipse and, if things look dicey, going somewhere else. Many choose their preferred viewing site based on the ability to get away. That’s one reason that Espenak viewed last month’s eclipse from Casper, Wyoming: the weather prospects there were good, and major highways running east and west along the path of totality meant a good chance to run to find a break in any clouds that might move in. The Astronomical League held its annual convention there, too.

Seattle Astronomy’s Greg Scheiderer with Stephen O’Meara at
the Seattle Astronomical Society meeting Aug. 16, 2017.

The week before the eclipse Steven O’Meara, a columnist for Astronomy magazine and an avid eclipse chaser, gave a talk to the Seattle Astronomical Society. He recounted how, as a young child, his mother showed him little eclipses reflected through the holes in their home’s window blinds.

“Partial eclipses have been dear to me ever since I was a child,” O’Meara said. He noted that a thought struck him after a recent similar presentation.

“I realized how wonderful partial eclipses are and how much more fun I have at partial eclipses, because there’s no pressure,” O’Meara said. We think he actually thrives on the pressure though, and he told a number of entertaining stories about last-ditch efforts to beat the clouds and catch at least a glimpse of an elusive eclipse. Some of the more interesting ones involved Pop Tarts and essentially hijacking a boat in Indonesia when it appeared there would be no eclipse viewing on land. He may well be the king of plan B.

My own plan

Writing the Seattle Astronomy blog and producing our podcast was my research and planning for last month’s eclipse. I’ve done 27 posts (including this one) and did 15 podcasts about the eclipse, with the subject of many being the question of why one would choose Stapleton, Nebraska or Nashville for eclipse watching over the other places in the path of totality. I learned a lot about the activities each community had planned, and what else there was to do there once an eclipse was over. With all of that information, I ended up picking Salem, Oregon. I had three reasons: proximity, population, and weather.

Data by NASA/GSFC. Graph courtesy
Jay Anderson, Eclipsophile.com

Proximity. I reasoned that, if I lived in the Salem area, I probably would not have gone anywhere else. I’d have gone to a local park, or sat in my own back yard, to watch the eclipse. One short move may have been to get a little closer to the center line. With Salem just a four-hour drive from Seattle, this seemed a sensible option.

Population. At some point in my deliberations, I decided that I preferred a more urban setting to a rural one. It seemed that accommodations, the ability to get around, and access to stuff like food and a porta-potty might be more likely in a setting with more infrastructure.

Weather. Yes, many people would and did laugh about this. Walk up to anyone and tell them that you plan to watch a solar eclipse in western Oregon, and about 80 percent of them will immediately laugh and declare that, “It will rain.”

Looking at Anderson’s chart above of weather along the path of totality revealed a different story, however. While, statistically, the weather in Salem on August 21 of any year isn’t as good as that in Madras, it’s still pretty close, and a far sight better than just about any place east of Missouri. Salem seemed a good bet. When the date arrived and climate turned into weather, it helped that we were in the middle of the driest, clearest summer anyone can remember.

Chuck it

As I asked people along the path if accommodations were available in their town or city, most of them noted that hotels don’t even book for more than a year in advance. In fact, I heard several funny stories about innkeepers befuddled by someone wanting to book a room five years ahead of time! Naturally, when I went online to look for reservations in Salem 13 months prior to the eclipse, everything was completely sold out. Some time later I stumbled across an available motel room in Lebanon, Oregon and snapped up the reservation. I got tickets to OMSI’s eclipse event at the fairgrounds in Salem, and I was ready to go.

Back in December I published a post and podcast interviewing Elaine Cuyler of Orbit Oregon, publisher of the kids’ book The Big Eclipse. Cuyler, a former marketing director for Eola Hills Winery near Salem, was putting together the Wine Country Eclipse festival at the Polk County Fairgrounds. She invited me to speak at the festival, complete with gratis lodging in a residence hall at nearby Western Oregon University in Monmouth. It seemed like a no-brainer, and I jumped at the chance. I cancelled my motel reservation and gladly stayed in the dorms at WOU (pronounced “woo”, according to the staff.)

So, after about 20 months of planning, I ended up doing something that was only finalized about two or three weeks ahead of the eclipse. As noted in my post about eclipse weekend, it couldn’t have worked out better.

Total solar eclipse, 2024

Map courtesy Michael Zeiler, GreatAmericanEclipse.com

If this year’s was “The Great American Eclipse,” then some are already dubbing the 2024 event “The Great North American Eclipse.” As you can see from the map at left, this one will first hit land in Mexico, swoop up through Texas, cross the path of the 2017 eclipse in Carbondale, Illinois, and zip northeast until it crosses Maine and the maritime provinces of Canada. Thanks to Micheal Zeiler of GreatAmericanEclipse.com for the map; Zeiler was one of our interview subjects, too!

So, where will you be in April 2024? I’ve been looking at Jay Anderson’s weather maps already, and it seems the best weather prospects will be in Mexico, but I’m leaning toward Texas right now. I’d try to make hotel reservations, but nobody books more than a year in advance. And some cool opportunity might turn up at the last minute.

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.

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.

“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.

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.

Dreamy musical astronomy show Starball plays Seattle

A dreamy, musical astronomy show will return to its birth town of Seattle next week after more than a decade away. Starball, created by John Kauffman and Dan Dennis, will play at West of Lenin in Fremont from September 7–11.

According to the show’s Facebook page, “Audience members play villagers in a dystopian future in which the global government, or World Regime, has ended the relationship between humanity and the stars. But two Astronomasons, the Conductor (Kaufmann) and the Proxy (Dennis), have rebelled, calling the villagers to a secret clearing for a creative ritual.”

It sounds a little dark, but director Rachel Katz Carey and producer A.J. Epstein call it “giddy fun.”

Carey said Kauffman and Dennis were the perfect people to create this show.

“They’ve got charm and charisma for days and they’ve got improv experience and they’ve got huge, open hearts, so people just want to jump in and work with them,” Carey said. “They also have the hard science. They’re not just theater guys who thought they found a gimmick; they really, truly know their astronomy.”

Both were working at the Willard Smith Planetarium at the Pacific Science Center when they created and first performed Starball in 2002. In 2004 they brought in Carey and Epstein to help take the show to new places.

“What they needed was scaffolding to give some form and structure,” Carey said. “It’s been my experience that improv thrives the best when there is a scaffolding and structure to support it.”

In the intervening years Starball has been performed in Chicago, New York, Philadelphia, Baltimore, Baton Rouge, and even Spain. For its return to Seattle it will be performed in an inflatable planetarium on the West of Lenin stage.

Epstein explained that as audience members enter they will be asked to anonymously jot down notes about a recent dream. During the performance dreams will be drawn at random, and the actors and audience will look for parts of the dream in the stars projected on the planetarium dome. The audience and actors together will create stories based on the dreams identified in the sky.

L-R: Seattle Astronomy’s Greg Scheiderer, Starball producer AJ
Epstein and director Rachel Katz Carey in front of the inflatable
 planetarium in which Starball will be performed Sept. 7-11
at West of Lenin. (Photo: Greg Scheiderer)

“By the end of the night we have an entirely new sky mythology, not just individual constellations but a mythology unique to that group of people,” Epstein said. “And then they write a song.”

“An original song for every show based on what’s shown up in the sky,” Carey added.

“A Jungian devotee would have a field day with this show,” Epstein laughed.

He laments that, as a culture, we’ve lost our connection to the night sky.

“Most of us now live in cities where we can maybe see a couple of stars,” he said, “so the show really is very loudly but very elegantly getting people to actually look up at the sky and make a connection.”

At Seattle Astronomy we like to explore the intersections of art and science. Some would set up a divide there, but neither Carey nor Epstein see it.

“That’s sort of a Mac/PC religion question!” Epstein laughed.

“The stars were art before they were science,” Carey said. “We’ve been telling stories about stars long before we had telescopes.”

“The best scientists and the best writers about science that I know absolutely have the connection to art and imagination,” Carey added. “How do you get the big discoveries if you can’t imagine ahead of your data and then do the work to see if it’s there?”

Both admit to bias because of their involvement, but insist that Starball is way different than any planetarium show you’ve ever seen.

“You just have to be there, and when you leave you’re different because you’ve figured some stuff out,” Carey said.

“This one really grabs an audience by the heart and brings them to a place where they get it,” Epstein added.

Starball runs at West of Lenin for seven performances September 7-11. Tickets are $20 and are available online. Early purchase is recommended because the planetarium will only seat around 40 people.

Solar eclipse dispatch from Monmouth--Totality!

My biggest concern about viewing today’s total solar eclipse was that, after doing 14 podcasts and at least 25 blog posts about the event over the last 19 months, it would be underwhelming.

Greg Scheiderer of Seattle Astronomy snapped a selfie while 

watching the eclipse from Western Oregon University.

Silly me.

I’ve seen Saturn hundreds—thousands?—of times, but I still do a little gasp whenever I get the planet into the field of view of my telescope. There it is! Crank that up about a thousand times, and that’s what I felt when I saw first contact of my very first total solar eclipse from “The Grove” at Western Oregon University in Monmouth, Oregon, and again when the diamond ring went away and the whole campus went dark as if a light switch had been thrown, revealing the Sun’s shimmering white corona for a glorious two minutes.

The intervening hour and 13 minutes (or so) between the onset of the eclipse and totality offered plenty of chances to observe interesting natural phenomena, tricks of light, and human behavior. The university had a number of semi-official viewing spots, on the football stadium and other athletic fields, mostly. But some hundred of us chose The Grove, with nice trees providing shade from the diminishing summer Sun, and also leaving easy access back into the lawn for a view of the progress of the eclipse.

My favorite eclipse watcher, or non-watcher, perhaps, was a young lad of seven or eight who kept stomping off from his family group muttering, “It’s not that impressive.” Some time into the eclipse another kid was heard informing the elders that he needed a bio break. Mom loudly exclaimed, in order to make the point emphatically, that you shouldn’t poop during an eclipse. She soon relented and escorted the kid to the loo, no doubt considering the consequences. Many of the kids in attendance—one of the weekend activities was a camp for children—seemed far more interested in play than in some dumb-ass sky thing the adults wanted to see. Where are the water-powered rockets when you need them?! Other kids were totally along for the ride, watching through their eclipse glasses or goggles and declaring, “It’s awesome.”

Mini eclipses project through oak leaves during the eclipse.

We saw the little mini eclipses projected through the gaps between oak leaves in The Grove. We noticed bright Venus popping out in splendor several minutes—an hour? Time moves at a different pace during an eclipse—before totality. It got considerably cooler. I kept looking west for a glimpse of the Moon’s shadow. I noticed that deep, twilight purple of dusk relatively high in the sky; was that the umbra, above us but not yet reaching ground? I’m not sure. Then—BAM! Just like that it was dark and there was that amazing corona. I’ve since seen social media posts from people who took photos, and the corona looks round in those images. I saw almost wing-like structure reaching out a couple of solar diameters on either side. The eye and the camera see very different things. As a total solar eclipse newbie, I took the advice of many: Don’t try to photograph totality; just watch and enjoy.

I was expecting to see more stars, but they didn’t really appear. I thought I saw Mars, just for a moment or two, but it was pretty close to the Sun, and it might have been a trick of the light. I couldn’t spot Mercury. I really just kept going back to the corona. I can see all of that other stuff most any time. I also didn’t catch any animal behavior. There are a few squirrels on campus, but I didn’t spot any of them going eclipse crazy.

Then, in what seemed like way less than the two minutes we were promised, the Sun came back out from the other side of the Moon. The glasses went back on, for most. Others began to pack up and head on their way. Said one kid: “Can we go play now.” But I can’t help thinking that the “It’s not that impressive” kid will wind up with a Ph.D. in astronomy. Old Sol works in mysterious ways. We stayed and watched as the Moon slowly slipped away, and in another hour the eclipse was really over.

The light and warmth came back and everything was as it was, even though everything had changed.

I will always remember this amazing natural spectacle, watched from a lawn at Western Oregon University.

I can’t wait for the next one, and already have a great plan for the eclipse of 2024.

Solar eclipse dispatch from Monmouth

Seattle Astronomy is in Monmouth, Oregon for the total solar eclipse. As of this writing, just after 1 p.m. on eclipse eve, the weather outlook is highly optimistic for eclipse viewing from Salem and environs. We noted that Cliff Mass named Salem number one in a Thursday article about eclipse weather, and stuck with that analysis in updates on Friday and Sunday.

We arrived in Monmouth at just after noon on Saturday, August 19, having set out from West Seattle at 8:04 a.m. after breakfast at Luna Park Café. Our goal: get to Salem ahead of the slackers, though it has been suggested that we actually ARE the slackers! Traffic problems were nil on Saturday morning. We took the I-205 route to avoid downtown Portland, and the only traffic delay we encountered on the trip south was a brief slowdown right near the PDX airport.

We’ve seen several reports of clear sailing on the highways from others headed into the path of totality, both here in the I-5 corridor and also in Eastern Oregon. It made us wonder if predictions of eclipse-ageddon traffic were merely ways to discourage the faint of heart from making the trip. This morning we’ve also seen reports that officials are now worried that previous light traffic means a super crush later today and on eclipse morning. We shall see; a big part of the job of “officials” is to worry, and we had some discussion of this in our blog and podcast with Jim Todd of OMSI last year. In any event, we’re here early and enjoying this college town.

We’re in Monmouth because we’re bunking at Western Oregon University. Greg is giving a talk about chasing the Sun at 3 p.m. today, Sunday, at the Wine Country Eclipse event. We’ll also be watching the eclipse there on Monday morning. Our original plan was to be at the OMSI event at Salem Fairgrounds until Orbit Oregon offered us the speaking gig at the festival.

A few local businesses are embracing the eclipse to a degree. Portland-based Breakside Brewery has created Path of Totality IPA, and several pubs in town are carrying the eclipse-themed brew. (We’ve been doing exhaustive research on this.) As we enjoyed a burger and a couple of pints over lunch at Main St. Pub & Eatery in downtown Monmouth, there was just a trickle of foot and vehicle traffic in mid-afternoon.

Monmouth would qualify as a small town at population just over ten thousand. We’ve seen no sign yet that the town and its infrastructure will be over-run with eclipse-watchers, though our wait at breakfast was a bit long this morning and many of the folks at J’s Café were wearing eclipse t-shirts of various designs, a sure mark of a tourist. We probably made the wait a bit longer for locals coming in for their Sunday breakfast! There are definitely more people around that there were on Saturday, but it’s hardly a crunch.

Even Monmouth City Hall is getting into the act; they’re not opening until 1 p.m. on Monday so that everyone can enjoy the eclipse.

We hope you do, too! Tell us about your eclipse destination in the comments!

We were on KING TV this morning talking solar eclipses

Seattle Astronomy‘s Greg Scheiderer was on the KING 5 television program New Day Northwest today for a segment about viewing solar eclipses! It was a fun time, and an enthusiastic studio audience had lots of questions after the recording. They just about had to drag me off in order to record the next segment!

Alas, fame is fleeting—they spelled my name wrong in the graphics on the program. That’s not what George M. Cohan (or maybe Oscar Wilde) suggested.

If you missed it, the video is at this link.

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 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 polluted 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.

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.



Videos of the July talks: