Category Archives: lectures

Equinox sunset watch, Tyson visit highlight week’s calendar

A visit from astrophysicist Neil deGrasse Tyson, the final Jacobsen Observatory open house of the year, and a seasonal sunset watch are the highlights of this week’s calendar of astro-events in the Seattle area.

Tyson, director of the Haden Planetarium in New York, narrator of the recent Cosmos television series, author, and host of the StarTalk radio show and podcast, will speak at Seattle’s Paramount Theatre on two nights this week, Wednesday, September 21 and Thursday, September 22, both at 7:30 p.m. Some tickets are still available for both appearances.

Ring in autumn

AlicesAstroInfo-145Join Alice Enevoldsen of Alice’s Astro Info at Solstice Park in West Seattle at 6:30 p.m. Thursday, September 22 to enjoy the first sunset of autumn. The equinox sunset watch will be Enevoldsen’s thirtieth such event, part of her NASA Solar System Ambassador service. The event is free, low-key, and always informative.

TJO wraps its season

Theodor Jacobsen ObservatoryThe final open house of the year is set for 8 p.m. Wednesday, September 21 at the Theodor Jacobsen Observatory on the University of Washington campus in Seattle. The talk for the evening, reservations for which are already all spoken for, will be by student Anya Raj, who has been interning with NRAO-NM over the summer and who has built a dual-dipole radio telescope. Raj will talk about amateur radio astronomy and making your own radio telescope. Volunteers from the Seattle Astronomical Society will be on hand in the observatory dome to conduct tours and, if the sky is clear, offer looks through its vintage telescope.

The popular open house series will be on hiatus for the fall and winter and will resume in April.

Club events

Seattle Astronomical SocietyThe Seattle Astronomical Society will hold its monthly meeting at 7:30 p.m. Wednesday, September 21 in room A102 of the Physics/Astronomy Building on the University of Washington campus in Seattle. Guest speaker Ethan Kruse, a graduate student in astronomy at the UW, will talk about Proxima Centauri b, the exoplanet recently found orbiting our nearest stellar neighbor. Kruse will discuss how much we know about the planet right now, and what we might learn in the coming years.

By way of preview, check our articles about a talk by Kruse at an Astronomy on Tap Seattle event from earlier this year, and about a presentation by Prof. Rory Barnes at Pacific Science Center last month exploring the potential habitability of the planet.

Tacoma Astronomical SocietyThe Tacoma Astronomical Society plans one of its public nights for 9 p.m. Saturday, September 24 at the Fort Steilacoom campus of Pierce College. The indoor presentation will be about the reasons for the seasons as we shift into fall. Weather permitting, club members will have telescopes out for looking at the sky.

Futures file

You can scout out future astronomy events on our calendar. New additions to the calendar this week include:

  • World Space Week events October 4–7 at the UW Planetarium
  • The BP Astro Kids November 12 look at the craters of the Moon

Up in the sky

The ice giants Uranus and Neptune are well-placed for observing this week. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope offer additional observing highlights for the week.

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Proxima Centauri b and the question of habitability

The discovery of evidence of a planet in orbit around our nearest stellar neighbor, Proxima Centauri, has people all agog and with good reason. It’s something of a misnomer, however, to call the exoplanet Proxima Centauri b “Earth-like.” Rory Barnes, a professor in the Department of Astronomy and the Astrobiology Program at the University of Washington, points out that the planet’s mass is probably somewhere between 1.3 and five times that of Earth.

Barnes

UW prof. Rory Barnes speaking at an Astronomy on Tap Seattle event earlier this year. Photo: Greg Scheiderer.

“There’s a lot of excitement about this planet because it is so close in mass to the Earth, but we don’t actually know if it’s even rocky like the Earth,” said Barnes during a recent talk at the Pacific Science Center. Barnes, who uses computer modeling to study the habitability of exoplanets, noted that even though Proxima Centauri is the next closest star, it’s still pretty far away at 4.24 light years. If the Sun were the size of a baseball resting on home plate at Safeco Field, Barnes said Proxima Centauri b would be a grain of sand in New York City. Still, he noted there’s understandable excitement about the discovery.

“The reason why I think that this is the biggest exoplanet discovery since the discovery of exoplanets is because it is still very close, at least relatively speaking,” Barnes said. “We really have a chance, with this planet, to potentially observe its atmosphere and its surface and maybe start to try and sniff out the presence of life on that planet. Or not. We don’t know yet. But being so close, it gives us a shot.”

Not really “like” Earth

While Proxima Centauri b is about the mass of Earth, plenty else is different. It’s twenty times closer to its home star than Earth is to the Sun, and goes around that star in just 11.2 days. We know little else about it. The star has just 12 percent of the mass and 14 percent the radius of the Sun, and its brightness is just one one-thousandth that of the Sun.

“This is a small, dim star,” Barnes said.

Is there life there?

Life requires energy, some bioessential elements, and liquid water. The energy and elements are abundant in the universe, so Barnes says the key to finding life elsewhere is liquid water.

“When we think about exoplanets, we’re really going to focus, at least for now, on surface water,” Barnes said. “Not only is it going to be easier to see, but it’s going to be more similar to the Earth and that gives us a better shot at maybe being able to interpret the observations that we’re going to get.”

The desire to find liquid surface water on a planet led us to the concept of the “habitable zone” around a star, an area where the temperature would be right for liquid water to exist. Barnes said Proxima Centauri b is smack in the middle of the habitable zone.

“This is a dream planet for those of us who study this field,” he said, but added a caveat: “Being in the habitable zone does not mean you’re habitable. It is just the first step we need to get to.”

“The habitable zone is jargon, and it’s really misleading,” Barnes added. “I apologize for my field for inflicting it on you!”

Barnes said there are several threats to habitability for planets orbiting M dwarf stars like Proxima Centauri. With the habitable zone so close to the star, there is potential that stellar flares could blow away the atmosphere of a planet within it. Planets that close are probably tidally locked, too, but this isn’t a deal-breaker; their atmospheres might distribute heat and energy effectively. Tidal heating could cause problematic volcanism.

Habitable zone chart

Barnes showed this chart demonstrating that while Proxima Centauri b is now within the habitable zone, the zone was once much further from the star.

The biggest threat to the habitability of Proxima Centauri b, according to Barnes, is that its star was once much bigger and brighter before it contracted into the dim, red phase it is in today. In the early years that would have meant that its habitable zone was out at a distance between .25 and .5 astronomical units, while Proxima Centauri b orbits at a mere .05 AU. Being so far inside the habitable zone after formation means that the planet could have lost all of its water and become a completely uninhabitable place like Venus. On the other hand, if Proxima Centauri b formed as something like Neptune, being so close to the star could have blasted away its hydrogen envelope.

“Maybe that planet could have actually transformed from an uninhabitable Neptune-like planet into a rocky planet like the Earth,” Barnes speculated. “This is what we at the University of Washington think is probably the best bet for how this planet could be habitable.”

Barnes is hopeful that the discovery of Proxima Centauri b will help boost support for the sorts of telescopes and observatories that can make the observations needed to learn more about this intriguing exoplanet and determine if it is habitable, and even inhabited.

While Barnes won’t give the odds of life there—there are way too many variables and so little we know right now—he sounds confident that we’ll find life somewhere. He noted that we’ve found life on Earth in the deep sea, extreme deserts, extreme cold, acidic environments, and under other harsh conditions.

“The realization that extreme life is everywhere is part of the astrobiological revolution that is occurring right now in science,” Barnes said. “This recognition that life finds a way gives us confidence as we go forward.”

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Annual Moon viewing festival highlights week’s calendar

The last installment of the Pacific Science Center’s Science Café series and an annual Moon viewing festival are the high points of this week’s astronomy events calendar.

Viewing the Moon

Seattle Japanese GardenThe popular annual Moon Viewing Festival at the Seattle Japanese Garden will be held beginning at 6 p.m. Saturday, September 17 at the garden, which is within the Washington Park Arboretum in Seattle. The evening will include music, a haiku contest, and a traditional Japanese Tea Ceremony. Volunteers from the Seattle Astronomical Society will be on hand with telescopes to offer a great, close-up view of the Moon. Unfortunately, as of this writing the event is sold out.

Farewell to the science café

Pacific Science CenterThe Pacific Science Center is discontinuing its Science Café program after more than ten years at The Swiss Restaurant & Pub in Tacoma, Wilde Rover in Kirkland, and, up until a year or two ago, T.S. McHugh’s in Seattle. The center plans to have many of the same sorts of speakers and topics at its new, onsite Science in the City lectures.

One final astronomy-themed science café remains on the calendar and will be held at The Swiss at 6:30 p.m. Tuesday, September 13Josh Krissansen-Totton of the University of Washington Astrobiology Program and Department of Earth and Space Sciences will give a talk titled “The Search For Life Beyond Earth.” Krissansen-Totton will go beyond the headlines and explore how astronomers and astrobiologists are trying to detect life on exoplanets, and when they’re likely to be successful. Admission is free. Bring questions; there’s always plenty of time for Q-and-A.

OAS meets

Olympic Astronomical SocietyThe Olympic Astronomical Society will hold its monthly meeting at 7:30 p.m. Monday, September 12 in room Art 103 at Olympic College in Bremerton. They plan to make a comet, among other activities.

Futures file

You can scout out future astronomy events on our calendar. New additions this week include:

Up in the sky

September often offers great weather for stargazing as it’s still typically fairly warm in the evenings but the nights are getting longer. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy have observing highlights for the week.

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Wednesday astronomy at UW

Most of the week’s astronomy activity is focused on a couple of events Wednesday at the University of Washington.

Seattle Astronomical SocietyThe Seattle Astronomical Society will hold its monthly meeting at 7:30 p.m. Wednesday, June 15 in room A102 of the Physics/Astronomy building on the Seattle campus. Society member John McLaren will give a presentation about solar exploration, covering early human interactions with the Sun and their unexpected impacts on our growing technology. He’ll discuss how we learned about the Sun before the space age, what we’ve since discovered from space-based observing, and what the future holds for solar observations from space. The meeting is open to the public.

TJO goes retrograde

Theodor Jacobsen Observatory

Photo: Greg Scheiderer.

After the SAS gathering you’ll have just enough time to dash up campus to one of the twice-monthly open houses at the Theodor Jacobsen Observatory, which begins at 9 p.m. With both Mars and Saturn in the retrograde parts of their orbits, the observatory director, Dr. Ana Larson, will talk about what that means, will discuss the historical context, and help visitors plot the motion of Mars against the background stars using a star map.

With both planets well placed for viewing, hope for clear skies and at peek at them through the observatory’s vintage telescope, operated by volunteers from the Seattle Astronomical Society.

Planetaria

The Willard Smith Planetarium at Pacific Science Center has several astronomy shows every day. Check our calendar for the schedule.

Pacific Planetarium in Bremerton will offer public shows on Friday, June 17, with hourly presentations at 5 p.m., 6 p.m., and 7 p.m. The topic will be star hopping: how to explore the heavens using the constellations and stars as a guide. Admission to the shows is $5.

Up in the sky

Jupiter, Mars, and Saturn all remain well placed for evening viewing these days, but there’s plenty more to see. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope have other observing highlights for the week.

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Space oddities at Astronomy on Tap Seattle

Things got a little strange at the most recent gathering of Astronomy on Tap Seattle, and not just because we were all drinking beer at Hilliard’s Beer Taproom in Ballard and enjoying eats from the Cave Man Food Truck parked outside. The event, organized by astronomy graduate students at the University of Washington, took on space oddities like Hanny’s Voorwerp and Thorne-Żytkow Objects.

Seattle Astronomy gets all sentimental about Hanny’s Voorwerp because it has a cool name and it was a subject of our third post ever when we started this effort in January 2011. The Voorwerp was noticed by Hanny van Arkle, a Dutch schoolteacher who was categorizing galaxies in Sloan Digital Sky Survey images as part of the Galaxy Zoo project. The object (voorwerp is Dutch for thing or object) appeared as a blue blob near the galaxy IC 2497.

What’s a voorwerp?

John Ruan

Graduate Student John Ruan spoke about Hanny’s Voorwerp at Astronomy on Tap Seattle May 25. Photo: Greg Scheiderer.

During his talk titled, “Citizen Discovers Strange Black Hole Echoes: The Science Behind Hanny’s Voorwerp,” UW graduate student John Ruan said there were four ideas about what it was. All of them were wrong.

Imaging artifact. It could have been just a blip on the camera, Ruan said, but other observers were able to spot it.

Unknown solar system object. Ruan said solar system objects move rapidly, but the Voorwerp was found on photographic plates made more than 50 years ago, and it hadn’t budged.

Distant, high-redshift galaxy. The redshift was not high enough for the Voorwerp to be at great distance.

Milky Way nebula. Conversely, it wasn’t something in our own galaxy, either, this time because the redshift was not great enough.

It was in examining the spectra, though, that Ruan said a clue was found. The emission lines were strong.

“To get emission lines that are this strong, you need a really, really bright source that emits a lot of high-energy light,” Ruan said, the kind of light you get from gas falling onto a black hole. “This is evidence that this object was produced by a quasar.”

Hanny's Voorwerp

Hanny’s Voorwerp appears as a green blob in this photo by NASA, ESA, W. Keel (University of Alabama), and the Galaxy Zoo Team.

There was just one small problem with the idea. There’s no quasar in any of the photos. Ruan said the quasar was probably created when the galaxy merged with a smaller one.

“It disturbs the gas in this larger galaxy, and this gas, some of it, because it’s disturbed it will fall into the center of the galaxy and fall into the black hole,” Ruan explained. This ignited the quasar, but at some point it literally ran out of gas.

“That quasar became quiet again, and it looked like just a normal galaxy, however the gas cloud that the quasar was shining on still appears to be lit up,” he said. “And that is Hanny’s Voorwerp.”

Similar objects have been discovered and are generally referred to as quasar ionization echoes. Ruan said Hanny’s Voorwerp will gradually fade as the ionization of the gas wears off.

The weirdest stars in the universe

Emily Levesque is just finishing her first year on the astronomy faculty at the University of Washington, and her research bailiwick fit perfectly into space oddity night.

Emily Levesque

Emily Levesque makes a point about TZOs. Photo: Greg Scheiderer.

“I study weird stars, strange stars, the really oddball stars that we can’t easily explain,” Levesque said. Indeed, she started out looking at the odd couple of stars: red supergiants and neutron stars.

Red supergiants are enormous, massive, relatively cool stars. The largest one found so far is so big that it’s surface, if it were plunked into our solar system in place of the Sun, would reach almost out to the orbit of Saturn. Neutron stars are the small, dense remains of supernovae. They are no bigger than a city.

“There’s only one thing that I can do to red supergiants and neutron stars to make them weirder at this point,” Levesque said. “If we put a red supergiant and a neutron star into a binary, and we merge them, we get a very, very weird object.”

The TŻO

The weird object is called a Thorne-Żytkow Object (TŻO) because Kip Thorne of Caltech and Anna Żytkow of the University of Cambridge hypothesized just this sort of thing way back in 1977. Żytkow heard that Levesque was studying red supergiants, and sent an email asking if she’d like to give a shot at spotting a TŻO. It was quite a challenge.

“A neutron star is the size of the city of Seattle,” Levesque said. “A red supergiant is bigger than the orbit of Jupiter. If you embed a neutron star inside a red supergiant it’s virtually impossible to detect.”

As with Hanny’s Voorwerp, the spectra were the key. Inside a TŻO, convection pockets would circulate material and create bizarre chemical processes. As stuff nears the neutron star at the core it would be bombarded with protons, changing it into a different element. Then as it nears the surface of the star, it would decay into yet something else. The process repeats. If the spectrum reveals the presence of elements that you would not normally expect to see at the surface of a cold star, you may be onto something.

Two years ago Levesque and her team looked at 100 red supergiants, and 99 of them appeared normal. The spectrum of one of them, HV 2112, showed unusual concentrations of rubidium, lithium, and molybdenum.

“This was a signature that we’d actually found the first example of a Thorne-Żytkow Object in the universe,” Levesque said.

If true, it means a new way to make stars and a new way to make elements. Levesque said they’re still calling the star a candidate or possible TŻO because of the Sagan Standard that holds that extraordinary claims require extraordinary evidence.

“The evidence that we have is really compelling, but it’s three little blips in a spectrum,” Levesque said. “We desperately want to find more of these, we want to find other ways of detecting them. We’d ultimately love to have a whole set of Thorne-Żytkow Objects, and have a whole set of stars that we can look at that can hold the title of weirdest star in the universe.”

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Mars at opposition, AoT looks at weird objects

Mars from Hubble

Astronomers using NASA’s Hubble Space Telescope captured this striking image of Mars on May 12, when the planet was 50 million miles from Earth. Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), J. Bell (ASU), and M. Wolff (Space Science Institute).

The season of Mars begins this week as the Red Planet reaches opposition on Sunday, May 22! That means that Mars will rise around sunset, be highest in the southern sky at around 1 a.m., and will be visible all night long. When Mars is at opposition it also is near its closest approach to Earth, which this year happens on Memorial Day.

This year’s apparition is a particularly favorable one for Mars, which will draw nearer to Earth than it has been in more than a decade. At closest approach on May 30 Mars will be just 46.8 million miles away from us; it will be at its brightest for the year and we will have our best chance to see surface details through our telescopes. After Memorial Day Mars and Earth will slowly get further apart and Mars will appear to grow dimmer. The best views will be through June, but Mars will be reasonably well placed for observation through the rest of the year.

This NASA site has good information about the Mars opposition and current activity on the Red Planet.

Space oddities

AoT Seattle May 25, 2016The next edition of Astronomy on Tap Seattle is coming up at 7 p.m. Wednesday, May 25 at Hilliard’s Beer Taproom in Ballard. The monthly event organized by graduate students in astronomy at the University of Washington this time takes a look at real-life space oddities. UW astronomy professor Emily Levesque will talk about her research on “The Weirdest Stars in the Universe,” and grad student John Ruan will give a talk titled, “Citizen Discovers Strange Black Hole Echoes: The Science Behind Hanny’s Voorwerp.”

Astronomy on Tap also features trivia contests, good beer, good science, and a lot of fun. There are typically more participants than there are chairs, and the organizers suggest you can bring a lawn chair and create your own premium seating.

Fly above it all

Above and BeyondAbove and Beyond: The Ultimate Interactive Flight Exhibition opens May 28 and runs through September 10 at the Museum of Flight. It’s the west coast premiere for the exhibition, which explores the wonder of flight and the marvels of aerospace innovation, design, and technology. Above and Beyond is designed to be the most interactive touring exhibition on aerospace, with approximately 5,000 square feet of exhibition space, including a 180-degree immersive theater presentation, a high-tech media-rich historical timeline, a simulated space elevator ride, a challenge to design and test a supersonic fighter jet in a virtual high-speed flying competition, and an avatar-based motion-capture group experience that demonstrates flight like a bird.

Astronaut Tom Jones

Astronaut Tom Jones. Photo: NASA.

Seattle Astronomy plans to run a full-length preview of the exhibition later this week. It has been at the Smithsonian and in Abu Dhabi, and recently wrapped up runs at the St. Louis Science Center and the Gaillard Center in Charleston, South Carolina.

Shuttle astronaut Tom Jones will be at the museum Saturday to help kick off Above and Beyond. At 2 p.m. Jones will give a talk about what it’s like to fly in space. Afterward, he’ll sign copies of his book, Ask the Astronaut: A Galaxy of Answers to Your Questions on Spaceflight (Smithsonian Books, 2016). The lecture, and the exhibition, are free with admission to the museum.

Books by Tom Jones:

Up in the Sky

With Mars reaching opposition we have a pretty good three-planet show in the evenings. Jupiter was at opposition March 8 and these days is high in the south at dusk and sets around 2 a.m. Saturn will be at opposition June 3. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy have additional observing highlights for the week.

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New Horizons reveals much, raises questions about Pluto

I overheard a little academic snark after a recent University of Washington astronomy colloquium. “It must be nice to be a planetary scientist,” said one attendee. “The answer to everything is, ‘I don’t know.’”

Grundy

Will Grundy. Photo: Lowell Observatory.

The topic of the day was Pluto, and the speaker was astronomer Will Grundy of Lowell Observatory. Grundy is a co-investigator for the New Horizons mission that flew past Pluto last July and will be beaming data back to Earth through the end of this year. He heads up the mission’s surface composition science theme team.

To be sure, Grundy’s talk was peppered with words like probably, puzzle, conjecture, speculation, and, yes, “We don’t know.” To be fair, we have learned quite a lot from a spectacular collection of snapshots beamed back to Earth from a dwarf planet three billion miles away. UW astronomy professor Don Brownlee talked about the scientific achievement, and the advances of the last 50 years, in his introduction of Grundy.

“Mariner 4 went to Mars and took 22 exciting pictures which we would now think were absolute dirt because they were 200 by 200 pixels and had very poor signal-to-noise ratio,” Brownlee said. “We’ve had this fantastic half-century of discovery of things where objects in the solar system went from dots to actual worlds. The last first-time is Pluto.”

One thing that we know fairly definitively is the variety of materials that are on Pluto’s surface. Grundy, who is a spectroscoper, showed many of the colorful images that reveal which compounds are there.

“The outer solar system would be a really colorful place if our eyes could just see a little farther out into the infrared,” Grundy noted, “but I guess it wasn’t advantageous to us running around on the African savannah to be able to distinguish methane ice from nitrogen ice.”

Psychedelic Pluto

“The outer solar system would be a really colorful place if our eyes could just see a little farther out into the infrared,” says New Horizons scientist Will Grundy. Mission scientists made this false color image of Pluto using a technique called principal component analysis to highlight the many subtle color differences between Pluto’s distinct regions. Image Credit: NASA/JHUAPL/SwRI.

Many other images showed the fascinating and varied terrain of Pluto, and this is where a lot of the we-don’t-knows come in. There are features that look for all the world like drainage canals, but it’s way too cold on Pluto for liquids. Perhaps the features were caused by glaciers, or some material we don’t know about. Other areas show what look like sand dunes with ripples on them, but Pluto’s atmosphere is too thin to blow sand around. Perhaps there was a thicker ancient atmosphere. Each photo revealed amazing detail and features, and many may well remain mysteries until more data can be collected.

“All of these different things are going on on different time scales,” Grundy said. “Sorting out the processes that we’re seeing here is going to be a fun challenge.”

The images are truly remarkable, though Grundy suggested they’re even better in higher resolution than he could display on the lecture-room screen. He suggested delving into the New Horizons image archive for some good viewing.

Pluto may seem insignificant to some, especially in light of its reclassification to dwarf planet, but Grundy said it’s well worth it to explore the “cold fringes of the solar system.”

“These things are really faint, really far away, really hard to get to, not huge,” he said. “Arguably they are the debris that’s left over from the formation of the giant planets, and they preserve a lot of clues about the planet-formation process specific to our solar system and perhaps general solar systems more broadly.”

“From my point of view, I’m just interested in exploration, just seeing what the objects out there are like.” Grundy continued. “If you like geology, or real estate, most of the solar system’s solid surface is out there.”

As New Horizons continues to beam back data it collected during last summer’s fly-by, it also is zipping toward another Kuiper Belt object, 2014 MU69, at which it will arrive on New Year’s Day 2019.

There’s another chance to catch Grundy’s presentation about Pluto coming up this weekend. He is scheduled to give a talk titled “Pluto and Charon Up-close” at 2:15 p.m. Sunday, May 22 at the PACCAR IMAX Theater at the Pacific Science Center. It’s part of the center’s on-going observance of AstronoMay.

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