Category Archives: lectures

The search for Earth 2.0

Astronomers have to date discovered more than 3,700 exoplanets—planets in orbit around stars other than our Sun. With each discovery, someone wants to know if the newly discovered planet is like Earth.

Elizabeth Tasker

Elizabeth Tasker at Astronomy on Tap Seattle.

Elizabeth Tasker thinks that’s not a very good question. Tasker, associate professor at the Japan Aerospace Exploration Agency, Institute of Space and Aeronautical Science and author of The Planet Factory: Exoplanets and the Search for a Second Earth (Bloomsbury Sigma, 2017) gave a talk at the most recent edition of Astronomy on Tap Seattle. She said that some of the exoplanets confirmed so far have at least a little resemblance to Earth.

“Roughly one third of those are approximately Earth-sized, by which I mean their physical radius is less than twice ours,” Tasker said. News media often wish to leap from that to describing a planet as Earth-LIKE, but Tasker said we don’t have nearly enough information to make that sort of call. Our current methods of detecting an exoplanet can give us either its radius or its minimum mass, and a pretty good read of its distance from its host star.

“The problem is neither of those directly relates to what’s going on on the surface,” Tasker noted. Part of the challenge is what Tasker feels is the somewhat oversimplified notion of the “habitable zone” around a star, a band of distance in which liquid water—a key to life as we know it—could exist on a planet’s surface.

“Like all real-estate contracts, there is small print,” Tasker said. “Just because you’re inside the habitable zone doesn’t mean you’re an Earth-like planet. Indeed, of all the planets we’ve found in the habitable zone around their stars, there are five times as many planets that are very likely to be gas giants like Jupiter than have any kind of solid surface.”

Another misleading metric that has been used is something called the “Earth similarity index.” This method compared exoplanets to Earth on the basis of properties such as density, radius, escape velocity, and surface temperature.

“None of these four conditions actually measure surface conditions at all,” Tasker said, pointing out that the index didn’t take into account such features as plate tectonics, a planet’s seasons, it’s magnetic fields, greenhouse gases, or existence of water. We can’t observe any of those things about exoplanets yet. As an example of the flaws of the index, Venus came out at 0.9, pretty similar to Earth, which is at 1.0 on the zero-to-one scale. While Venus is about the size of Earth and is around the inner edge of the Sun’s habitable zone, its surface temperature could melt lead. Not very Earth-like, or habitable. It’s one of the reasons that the index is seldom used these days. So we don’t have much of a clue about conditions on any of the known exoplanets.

“Our next generation of telescopes is going to change that,” Tasker said. She noted that NASA’s James Webb Space Telescope is scheduled to launch next year, the ESA’s Ariel in 2026, and the UK’s Twinkle in the next year or so.

“All of these are aiming at looking at atmospheres, and these may be able to tell us what is going on on the surface, and may even give us the first sniff of life on another planet,” Tasker said. “Maybe then we’ll be able to talk seriously about Earth 2.0.”

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Serious fun with astronomy, history, and literature

The University of Washington College of Arts and Sciences is presenting a monthly Serious Fun Lecture series, and the event next week includes Brett Morris, co-founder of Astronomy on Tap Seattle and a Ph.D. candidate in the dual-title Astronomy and Astrobiology Program. Morris will be one of three speakers to tackle the topic “Secrets and Mysteries.”

Brett Morris

Brett Morris

“We hope to evoke your curiosity, with mysteries and secrets across disciplines,” Morris said. “I’m honored to be speaking alongside two distinguished faculty who work in history and literature, and wade into mysteries just as much as astronomers do. I’ll tell the story of one of the most important astronomers you’ve never heard of, and the mystery she uncovered in our Universe—and how we might solve it.”

The other speakers will be Andrew Nestingen, Chair and associate professor in the Scandinavian Studies Department, and Laurie Sears, Walker Endowed Professor in History.

The lecture will be held at 7 p.m. next Wednesday, February 21, in the Brechemin Auditorium, which is on the east end of the School of Music’s main floor in the Music Building on the UW campus in Seattle. The lecture is free but registration is required.

A March lecture in the series will be about dragons, and in April they’ll take on time.

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Calendar: UW colloquium and AOT Seattle this week

A couple of interesting talks and no less than five club meetings fill the astronomy event calendar for this week.

UW Astronomy Colloquium

Juno at Jupiter

Juno at Jupiter. Image: NASA

Come learn about what the Juno mission is accomplishing at Jupiter. Sam Gulkis of the NASA Jet Propulsion Laboratory, one of the co-investigators for Juno, will speak at the University of Washington astronomy colloquium at 4 p.m. Thursday, February 15 in the Physics/Astronomy Auditorium on the UW campus in Seattle. Often the colloquia are a little heavy for the non-scientist audience, but this one sounds approachable. Gulkis will discuss how Juno peeks under Jupiter’s clouds using microwaves and other techniques, and he’ll fill us in on some of the mission’s early findings.

Astronomy on Tap Seattle

AOT Feb 2018Astronomy on Tap Seattle has an unusual Friday gathering this month, with two talks, astronomy trivia, and great prizes on the docket for 7 p.m. February 16 at Peddler Brewing Company in Ballard. The topic for the evening will be Cosmic Explorers. Dr. Jen Sobeck, a senior research scientist in the UW Department of Astronomy, will talk about the Harvard Computers—the women who mapped the sky! Dr. Elizabeth Tasker, author of The Planet Factory: Exoplanets and the Search for a Second Earth (Bloomsbury Sigma, 2017) will talk about “Earth 2.0” and the search for a habitable world. (By the way, if you buy the book from that link, Seattle Astronomy gets a small royalty at no cost to you! It helps us do what we do. Thanks!)

AOT is free, but remember to buy beer. Bring a lawn chair to create your own front-row seating!

Cosmic love

The Washington State University Planetarium in Pullman has a special show planned for Valentine’s Day, Wednesday, February 14. “Some Like It Hot” will show at 7 p.m. and again at 8:30. It’s not the movie with Marilyn Monroe, and Tony Curtis; this planetarium show is all about temperature—from the frigid to the muy caliente, the universe has it all.

Admission is $5 cash or check at the door. No credit cards are accepted at the planetarium.

Check our calendar page for a list of links to other planetaria in the area.

Astronomy club meetings

The Island County Astronomical also plans a public star party for 7 p.m. Friday, February 16 at Fort Nugent Park in Oak Harbor.

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Astronomy’s neglected stepchild

Robert Reeves has been an astronomer for nearly 60 years. The Moon was his first love; he shot his first photograph of it in 1959, and laments that it isn’t such a popular target for amateur astronomers any more.

Robert Reeves

Astrophotographer and author Robert Reeves was the guest speaker at the annual banquet of the Seattle Astronomical Society on Jan. 28, 2018. Photo: Greg Scheiderer

“The Moon is not just that big ball of light pollution in the sky,” said Reeves during his keynote talk at the Seattle Astronomical Society’s annual banquet last month. “The Moon used to be a target for American technology. The Moon was a place to be explored; it was a destination.”

Reeves was interested in the Moon even before there was a space program. We were all agog during the race to land on the Moon, but when the race was won many moved on to other things.

“Back then American heroes rode a pillar of fire and dared to set foot on another world,” Reeves said. “The scientific mindset, the desire to explore the solar system was there. That was a time when America was only limited by its imagination; we could do anything we wanted to do”

Alas, Reeves notes, politics is different now.

“America has lots its will, it’s lost the guts to go into deep space,” he said. “We’ve been rooted in low-Earth orbit for four decades.”

“Space exploration is not the same, but the Moon that we wanted to go to still beckons us,” he added.

Bringing the Moon back

Reeves’s talk was titled Earth’s Moon: Astronomy’s Neglected Stepchild. He aims to turn that around.

“I’m here to bring the Moon back,” he said. “The Moon is still a viable target; we can see it from our own back yard.”

Reeves is a prolific writer about astronomy. His first published article appeared in Astronomy magazine in 1984. Since then he’s written some 250 magazine articles and 175 newspaper columns about the topic. In fact, just days after his talk here the March 2018 issue of Astronomy arrived, including an article and photos by Reeves about hunting for exoplanets. His mug also appears, along with one of his lunar photographs, on a back-cover advertisement for Celestron.

Reeves has written five books in all, including three how-to manuals about astrophotography: Wide-Field Astrophotography: Exposing the Universe Starting With a Common Camera (1999), Introduction to Webcam Astrophotography: Imaging the Universe With the Amazing, Affordable Webcam (2006), and Introduction To Digital Astrophotography: Imaging The Universe With A Digital Camera (2012). All are from Willmann-Bell.

Reeves feels the webcam book helped launch a whole industry and trained a generation of astrophotographers. He points out that back in the 1960s you could count the number of good astrophotographers with the fingers of one hand. Now there are thousands of people turning out great images, and they all get to use superior gear.

“Amateur instruments off the shelf today just blow away what the pros used to do on the Moon, and it’s relatively easy to do this,” Reeves said. I asked Reeves if he laments the passing of film photography. He said he did, a little, noting with a laugh that he has four decades worth of photography that is obsolete! But he said the fact that he can turn out more better-quality images in less time with digital makes up for that.

Check out Reeves’s website for a image-processing tutorial, to buy prints and posters, and find lots of other lunar photography information.

Asteroid 26591 is named Robertreeves and asteroid 26592 is named Maryrenfro after his wife; Renfro is her maiden name. It is believed they are the only husband and wife with sequentially numbered asteroids named after them! Robert noted that his takes about four years to orbit the Sun, while Mary’s goes around in about 4.4 years.

“Every ten years I catch up to her,” he said, “so for eternity I’m going to be chasing Mary around the solar system.”

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Books by Robert Reeves:

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Calendar: SAS banquet and Astronomy on Tap Seattle this week

The annual Seattle Astronomical Society banquet and Astronomy on Tap Seattle are the highlight events for the coming week. The Museum of Flight kicks off Astronaut Remembrance Week, and regional planetarium shows cap the calendar.

SAS Banquet

Robert Reeves

Robert Reeves

The Seattle Astronomical Society banquet always draws an excellent guest speaker, and this year is no exception: renowned photographer Robert Reeves will keynote the annual banquet, and talk in particular about observing and imaging the Moon. The banquet gets under way at 4 p.m. Sunday, January 28 at the Swedish Club on Dexter Avenue North in Seattle. Reservations are $65 for the general public, $55 for SAS members. Don’t wait; there were only 18 spots left as of this writing. Reservations are available online.

Reeves will do a special master class on lunar photography for the SAS Astrophotography Special Interest Group. The class is open to the public and will be held at 5:30 p.m. Saturday, January 27 in the Red Barn Classroom at the Museum of Flight.

Astronomy on Tap Seattle

AOT Seattle January 2018The topic will be exploring alien moons when Astronomy on Tap Seattle holds its first event of the new year at 7 p.m. Wednesday, January 24 in the beer garden at Peddler Brewing Company in Ballard. Second-year UW graduate student in astronomy and astrobiology Tyler Gordon will speak about his research on the search for exoplanetary satellites using current and future telescopes. UW Ph.D. student in oceanography Max Showalter will discuss looking for life when the trail goes cold, an update on his work using movement as a sign of life in icy places.

Showalter did a talk at Town Hall Seattle almost two years ago. Check our recap of that talk and learn how SHAMU is helping hunt for ET.

Planetarium shows

The Washington State University Planetarium in Pullman has a new show this week titled, “Millions of Miles to Mars.” The show explores the whats, hows, and whens of Mars visits. Showtimes are 7 p.m. Friday, Jan 26, and 5 p.m. Sunday, Jan 28. Tickets at the door are $5 cash or check; they don’t accept credit cards. Kids under six get in free.

The Willard Smith Planetarium at the Pacific Science Center has a variety of shows for all ages every day. Check their website for the complete calendar.

Astronaut remembrance

America’s three great spacefaring tragedies all occurred at this time of year. To honor the sacrifices of the fallen astronauts, the Museum of Flight holds an annual astronaut remembrance week. The event runs from Friday, January 26 through Sunday, February 4 and features displays and exhibits about the fallen astronauts and their accomplishments. Solar System Ambassador Ron Hobbs will give a presentation about the tragic missions, and about the risks and successes of space travel, at 2 p.m. Saturday, January 27. It’s free with museum admission.

Future file

A total eclipse of the Moon will be visible in the early morning hours of Wednesday, January 31. The event begins just after 3 a.m. PDT, the partial eclipse starts around 3:45, and it will be total from just before 5 a.m. until a little after 6:00. All you really need to do is go outside and look up, but if you want to watch with others, the Seattle Astronomical Society plans a group viewing event at Solstice Park in West Seattle.

You can always scout out future events on our calendar.

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Calendar: club events open December

As we flip the calendar to December, there are a couple of good headline events, four astronomy club meetings, and several educational events to look forward to.

Astronaut and mountaineer Scott Parazinski is the only person ever to have both flown in space and stood on the top of Mount Everest. He’ll be at the Museum of Flight at 2 p.m. on Saturday, December 9 to talk about his experiences and his new book, The Sky Below: A True Story of Summits, Space, and Speed (Little A, 2017). Parazinski will sign copies of the book after his talk, which is free with museum admission.

If you can’t make it Saturday, you can pick up the book by clicking the link above or the book cover at left; Seattle Astronomy gets a small royalty at no cost to you when you purchase this way, and it helps support our operations. Thanks so much!

Life in Space

The Pacific Science Center’s Science in the City lecture series continues at 7 p.m. Wednesday, December 6 with a program called Life in Space. Three University of Washington astrobiologists will discuss their research—including the search for planets around other stars, characterizing how stars influence the habitability of those planets, and techniques to mix computer modeling with data analysis to determine the characteristics of potentially habitable worlds. Two of the three presenters will be familiar to Seattle Astronomy readers. Brett Morris is a PhD candidate of astronomy and astrobiology at the University of Washington and is a co-founder and co-host of the popular Astronomy on Tap Seattle events. Dr. Erika Harnett is a research associate professor and was featured on the blog and podcast this year. The “new guy” is Marshall “Moosh” Styczinski, a grad student who does research using magnetic fields to peel back the icy crust of Jupiter’s moons, looking for places that life may be found.

After viewing the documentary The Search for Life in Space, the trio will answer questions about their research and other topics addressed in the film.

Tickets to Life in Space are $5, free for Pacific Science Center members.

Astronomy club activity

Four clubs have their monthly meetings this week:

In addition, two clubs have public outreach events on Saturday. The BP Astro Kids on Bainbridge Island will make LED holiday cards during sessions at 4 p.m. and 5 p.m. at the Ritchie Observatory on Bainbridge Island. Following at 7:30 p.m. the Battle Point Astronomical Association monthly planetarium show will focus on how neutron stars make gold, and how we can tell they’re doing it. The Tacoma Astronomical Society will hold one of its public nights at 7:30 p.m. Saturday, December 9 at the Fort Steilacoom campus of Pierce College. The indoor presentation will be a viewing of the movie The Christmas Star. At both the Battle Point and Tacoma events there will be stargazing if the weather permits.

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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.”

Neutron star merger animation by ESO/L. Calçada. Music: Johan B. Monell

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

Where stuff comes from

Periodic table showing origin of elements in the Solar System, by CMGLee on Wikimedia Commons based on data by Jennifer Johnson, Ohio State University.

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 showed the periodic table of elements at left (click to see it bigger), modified to show where all of the elements came from. She noted that hydrogen, helium, and a bit of lithium came from the Big Bang, the rest 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.

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