Cannibal galaxies and asteroid mining

Our galaxy is a cannibal, and we have quite an appetite for resources in our own little corner of the Milky Way, too. That’s what we learned at the latest Astronomy On Tap event in Seattle, held last week at Bad Jimmy’s Brewing Company in Ballard.

John Lurie

John Lurie talked about the cannibal Milky Way galaxy at Astronomy on Tap Seattle. Photo: Greg Scheiderer.

John Lurie, a graduate student in astronomy at the University of Washington who studies the structure of the Milky Way, started his talk with a bit of history. For millennia, up until recently when light pollution made the Milky Way invisible to a great many of us, people saw it and made up stories about what it was. To Lurie’s mind, some of the violent images of Greek mythology seem fitting.

“Our Galaxy is actually a cannibal, and it likes to eat other galaxies,” he said. “Not only that, but the entrails of its victims are strewn across the heavens.”

We didn’t know much at all about the Milky Way until Galileo pointed his telescope at it four centuries ago and wrote down that he saw individual stars.

“Up until the beginning of the 20th century that was basically it,” Lurie said. “The entire universe, as far as we knew, was contained in the Milky Way.”

New learning

Fast forward to Edwin Hubble, who used a much larger telescope, the 100-inch at Mt. Wilson, to look at cepheid variables. Hubble calculated that what was then known as the “Andromeda nebula” was about 2.5 million light years distant—way too far away to be part of our galaxy. It was another galaxy.

If this ball were the Sun, the next nearest star would be in New York. Photo: Greg Scheiderer.

If this ball were the Sun, the next nearest star would be in New York. Photo: Greg Scheiderer.

Galaxies seem awfully far-flung to be cannibalizing each other, but Lurie explained that they’re actually relatively close together. He noted that if the Sun were a yellow ball a bit smaller than a pint beer glass (an apt analogy given the locale of the talk) our next nearest stellar neighbor would be in New York. However, if the disk of the Milky Way galaxy were represented by a frisbee, the next nearest major galaxy would be inside Bad Jimmy’s, a mere 20 feet away. In addition, between us and Andromeda are a number of dwarf galaxies. Astronomers have found streams of stars that are evidence that the Milky way has collided with one of them, the Sagitarius dwarf galaxy.

“That’s why I claim that our galaxy is actually a cannibal,” Lurie said. “It’s in the process of eating this galaxy. Gravitational tidal forces of the Milky Way are tearing the stars off of this dwarf galaxy and they’re being strewn out into space.”

Bigger fish

Lurie says that when it comes to cannibal galaxies there’s always someone bigger out there.

“The Andromeda galaxy is coming to get us,” he said. “It’s a little bit bigger than us, and we’re on a collision course.”

Not to worry. It won’t happen for another four billion years or so, and since individual stars are so spread out, the likelihood that two would collide is pretty small. Some stars could get flung out of the galaxy, but mostly the Milky Way and Andromeda will eventually coalesce into one big galaxy.

Mining asteroids

Matt Beasley of Planetary Resources explained the best types of asteroids for mining useful materials. Photo: Greg Scheiderer.

Matt Beasley of Planetary Resources explained the best types of asteroids for mining useful materials. Photo: Greg Scheiderer.

Closer to home folks are thinking of mining nearby asteroids for the valuable materials they contain. Dr. Matthew Beasley, a senior engineer at Redmond-based Planetary Resources, gave a talk titled, “Resources on Asteroids: What’s There, How Much, and Why?”

Beasley noted that there are 872 known asteroids of about one-kilometer orbiting in near-Earth space, and perhaps as many as 20,000 smaller ones down to about 100 meters. That’s a lot of potential targets for asteroid mining.

Why go to the trouble?

“Asteroids are extremely rich in useful materials,” Beasley said.

There are three main types of asteroids. Beasley explained that the first ones Planetary Resources will target are C-type carbonaceous asteroids. These make up about 75 percent of all asteroids, but only about six percent of the known near-Earth asteroids. They’re hard to spot because they’re so dark in color, like a lump of black clay. C-type asteroids are around 20 percent water by mass, and that’s what makes them appealing. Water is handy for space explorers to drink, and it can be broken down into hydrogen and oxygen for spacecraft fuel.

“One 75-meter C-type asteroid full of water could have fueled all of the shuttle missions,” Beasley noted. It will cost a lot less to pick up water and fuel in space than it does to launch them into space from Earth.

The second target type of asteroid is the M-type, which is heavily metallic. M-type asteroids contain virtually no water, but are rich in metals such as nickel, iron, and platinum, and maybe some silicates.

“One 500-meter metallic contains more platinum than has ever been mined by humanity,” Beasley said, adding that all of the platinum on Earth probably got here through collisions with asteroids. Platinum-group metals are highly sought after for electronics and other manufacturing, and all of the metals could be useful for building things in space. As with the water, it’s a lot less expensive to find it out there than it is to take it with you.

aotjuneA third common asteroid is the stony S-type. These contain no water, some metals, but basically are between 75 and 90 percent silicates.

“They’re a little light on volatiles and organics, lots of rock,” Beasley said, noting there’s little interest in this type of asteroid. “Basically, they’re fill dirt.”

The next Astronomy on Tap Seattle is set for 7 p.m. Wednesday, June 24 at Bad Jimmy’s. They’ll be viewing the first episode of the original Cosmos television series, featuring Carl Sagan. Idea: grab the book to read beforehand; you’ll have a leg up in the Cosmos trivia competition at the event! A guest speaker will introduce the episode, lead discussions and answer questions about it, and give updates on discoveries since the series first aired. It’s free, RSVP here.


Seattle Astronomy calendar, week of May 25

It’s a light week for astronomy events in the Puget Sound area, though the Tacoma Astronomical Society holds a public night on Saturday and there are several notable anniversaries this week.

Learn about black holes at the Tacoma Astronomical Society public night at the Fort Steilacoom campus of Pierce College starting at 9 p.m. Saturday, May 30. If the weather is good there also will be telescopes and observing outdoors. Directions and more on the TAS website.

Happy birthday to Sally Ride

Tuesday would have been the 64th birthday of astronaut Sally Ride, the first U.S. woman in space. Ride passed away in 2012. She joined NASA in 1978 and  took her first space flight aboard the shuttle Challenger, launching on STS-7 on June 18, 1983.

Journalist Lynn Sherr wrote a biography of Ride that was published last year. Sally Ride: America’s First Woman in Space is an interesting read about Ride, who became close friends with Sherr, who covered space news for ABC television. Sherr spoke about the book in August of last year at Town Hall Seattle. Read Seattle Astronomy‘s recap of the talk.

“Before this decade is out…”

The Soviet launch of Sputnik fired up the space race, but President John F. Kennedy kicked it into high gear with his speech to Congress on May 25, 1961, urging the nation to “commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.” The speech also kick-started NASA’s budget, which increased more than tenfold between 1960, when it was just over $400 million, and 1964, when it topped $4 billion. By 1966 it peaked at more than $5.9 billion. We all know that the goal was achieved.

ESA turns 40

Happy anniversary to the European Space Agency, which turns 40 this week. The ESA was formed May 31, 1975.


Astro Biz: Moondrop Coffee

Many businesses, products, and places have names rooted in space and astronomy. We’re featuring them regularly on Seattle Astronomy.

IMG_453653425Today’s Astro Biz is Moondrop Coffee at 1619 Harbor Avenue Southwest, just across the street from Seacrest Park and the King County Water Taxi dock in West Seattle.

I discovered Moondrop recently by happy accident. My bride just started a new job with the Seattle City Employees’ Retirement System and is commuting by Water Taxi. The dock is just a 20-minute walk from Seattle Astronomy headquarters, and I started making the stroll with her to get my blood pumping in the morning. She said, by way of inducing me into the a.m. march, “There’s a little coffee shop right down there.” Cool that it turned out to be an Astro Biz as well!

As I popped in after the boat left the dock, the commuters were gone, it was quiet, and I had the place to myself. They make a darn fine Americano! Moondrop also serves tea, juice, smoothies, and has bagels, sandwiches, waffles, banana bread, and other light munchies.

More info:

Do you have a favorite Astro Biz? Send us a photo and a brief description, and you may be featured in a future Astro Biz!


Seattle Astronomy calendar, week of May 18

There are a lot of great events requiring some difficult choices on this week’s calendar.

Prof. Jim Peebles speaks Tuesday at the University of Washington. Photo: Princeton.

Prof. Jim Peebles speaks Tuesday at the University of Washington. Photo: Princeton.

On Tuesday, May 19, Professor P.J.E. Peebles, Albert Einstein Professor of Science at Princeton University, will give a guest lecture at the University of Washington sponsored by the departments of physics and astronomy. Titled “50 Years of the Cosmic Microwave Background: What We Have Learned, and What Questions Remain,” Peebles’ lecture will explore the science behind the Big Bang and new searches for dark matter and dark energy. The lecture, at 7 p.m. in room A102 of the Physics/Astronomy Building on the UW campus in Seattle, is free, but reservations are required.

Jennifer Wu photography

Light Painting by Jennifer Wu.

Light Painting by Jennifer Wu.

At the same hour astrophotographers may be interested in a presentation by Jennifer Wu at the Mountaineers Seattle Program Center. Wu, the co-author of Photography Night Sky: A Field Guide for Shooting After Dark, is a nature and landscape photographer specializing in creating stunning images of the night sky and stars. Since 2009, she has served as a Canon Explorer Of Light, one of just 36 photographers worldwide to be recognized with that honor.

Tickets are free for students, $14 for Mountaineers members, $16 for non-members. The event starts at 7 p.m. Tuesday, May 19 at the Mountaineers’ Center, 7700 Sand Point Way NE in Seattle.

Astronomy on Tap returns

aot3Enjoy beer and astronomy at the third event of the spring with Astronomy on Tap Seattle on Wednesday, May 20 at 7 p.m. at Bad Jimmy’s Brewing Company in Ballard. UW astronomy grad student John Lurie will give a short talk about our understanding of the evolution of the Milky Way, titled, “Our Galaxy is a Cannibal.” Dr. Matt Beasley of Planetary Resources will discuss asteroid mining. In addition to the brew and lectures, there will be astronomy trivia contests and yummy prizes from Trophy Cupcakes.

Catch our recaps of the first and second Astronomy on Tap Seattle events, and we’ll see you at number three on Wednesday. It’s free; make a reservation here.

Seattle Astronomical Society

The Seattle Astronomical Society will hold its monthly meeting Wednesday, May 20 at 7:30 p.m. in room A102 of the Physics/Astronomy Building on the University of Washington campus in Seattle. Developer Jonathan Fay will talk about Microsoft WorldWide Telescope, free software you can use to plan observations, control a telescope, explore astronomical data sets, or create custom tours for educational outreach.

Back to TJO

Theodor Jacobsen Observatory

May 20 is the third Wednesday of the month, which means it’s time for another open house at the Theodor Jacobsen Observatory on the UW campus. The event gets under way at 9 p.m. Undergrad Boren Li will give a talk titled, “Comparative Planetology: Where Will We Go?” Li will compare conditions on other planets to those on Earth and summarize our best prospects for colonization.

The talks are free but reservations are strongly recommended. Volunteers from the Seattle Astronomical Society will give tours of the observatory and, weather permitting, share a look through its vintage telescope.

Northern lights flick at PacSci

Acclaimed Norwegian solar physicist Pål Brekke will be at the Pacific Science Center Thursday, May 21, for a discussion of the fascinating phenomena of the aurora borealis. They’ll show Brekke’s new 25-minute documentary The Northern Lights: A Magic Experience at 7:30 p.m. in the center’s PACCAR Theater. The film tells the full story of the aurora and includes tips on how to take your own exquisite northern lights photos.

After the screening Brekke will talk about his experience as a longtime observer of the northern lights and about his work on the documentary. Admission is $5. View the trailer for the film below.

Weekend star parties

The Seattle Astronomical Society will hold its free public star parties Saturday, May 23 at two locations: Green Lake in Seattle and Paramount Park in Shoreline. Both events will start at 9 p.m. if the weather is suitable for stargazing.

Saturn at opposition

Saturn will be at opposition Friday, meaning we’ve arrived at the best time this year for observing the ringed planet. Jupiter and Venus are still great targets in the early evening as well. This Week’s Sky at a Glance from Sky & Telescope magazine has more observing highlights for the week.

Keep on top of area astronomy events with the Seattle Astronomy calendar.



Astro Biz: Sun Drive-in Cleaners

IMG_0933Many businesses, products, and places have names rooted in space and astronomy. We’re featuring them regularly on Seattle Astronomy.

Today we feature Sun Drive-in Cleaners at North 45th Street and Woodlawn Avenue North in Wallingford. We’ve never used their services, as the shop is a bit far away from our headquarters in West Seattle. It’s on the same street and about a mile west of another recent Astro Biz, the Blue Moon Tavern.

Do you have a favorite Astro Biz? Send us a photo and a brief description, and you may be featured in a future Astro Biz!

Astro Biz index


Game of Thrones and black holes at latest Astronomy on Tap

The extreme seasons on the popular HBO series Game of Thrones and supermassive black holes were the subjects of talks at the most recent Astronomy on Tap event held at Bad Jimmy’s Brewing Company in Ballard.

AoT vs. GoT: Reasons for the (Extreme) Seasons

Russell Deitrick

Russell Deitrick makes a point during his talk at Astronomy on Tap II at Bad Jimmy’s Brewing Company. Photo: Greg Scheiderer.

Russell Deitrick is an graduate student in astronomy at the University of Washington, studying models of the dynamics of exoplanets in multi-planet systems. He is particularly interested in how interactions between planets with high eccentricity and high mutual-inclination might affect habitability of those planets. That, it would seem, makes him the perfect one to figure out what could cause the sort of long, severe, and unpredictable seasons the characters on Game of Thrones experience.

Deitrick started with a quick primer on what causes seasons. The main cause is the axial tilt, or obliquity, of the planet. Earth, for example, has an axial tilt of about 23 1/2 degrees, and when a pole is inclined toward the Sun its hemisphere enjoys summer.

There are several ways to mess with the seasons, Deitrick explained. Our Moon stabilizes precession—the wobble of the orbital axis like a top—so if a planet doesn’t have a large moon, precession would be greater and there would be more variance. You could alter the orbit itself, making it highly eccentric.

Other factors that can change climate include volcanism, solar variability, or having a planet in a binary star system.

Deitrick ran computer models in which all of these varied wildly. The simulations didn’t match the show.

“Eccentricity can’t really explain the duration of the seasons on Game of Thrones,” Deitrick said. “If you’re at high eccentricity, you may have a very long winter, but you’re going to have a correspondingly short summer, and the seasons are going to be the same length.”

He noted that changing the obliquity of the axis can explain everything except the long duration of the seasons. Volcanos can create long seasons, but Deitrick said that doesn’t fit in with the show.

“The problem with the volcanic winter is that it’s possibly too random,” he said. “The fact that the seasons are quasi-predictable suggests that it probably isn’t related to volcanos.”

He said solar variability takes to long to create climate change on the short time scale of a season, and a binary star system doesn’t appear to be part of the story in Game of Thrones.

“You’d think they’d mention somewhere in the series that there were two suns,” he said.

“None of these can explain that long night, that generation of darkness,” Deitrick added.

“The seasons on Game of Thrones probably can’t be explained by a single theory,” Deitrick concluded. “So they’re probably magic.”

Supermassive black holes: size matters

Michael Tremmel

Michael Tremmel is working on figuring out how supermassive black holes came to be. Photo: Greg Scheiderer.

Michael Tremmel, another UW astronomy grad student, took on an equally mysterious if less fictional topic in his Astronomy on Tap talk: supermassive black holes.

Tremmel explained that an ordinary black hole—one of between one and 10 solar masses—is the result of simple stellar evolution.

“When a massive star runs out of fuel and explodes in a supernova, the core of the star continues collapsing and forms a black hole,” he said.

The problem is that supermassive black holes can be of billions of solar masses and could not have formed in the same way.

“It’s still an open question where these black holes came from,” Tremmel said, “but we think that they must have formed very, very early on in the universe when the first stars that exist were beginning to form. Before there were galaxies, before there were stars, there were supermassive black holes.”

We’ve never seen a black hole because they don’t emit light. Their gravity is such that even light can’t break free. But the evidence that they exist is plain. Tremmel explained that we have observed stars orbiting rapidly around the center of our own galaxy. By gauging the trajectories of these stars we reach one conclusion about what they are orbiting.

“This object must be really, massive, and really, really small,” he said. “The only thing this thing could be is a black hole that is a billion solar masses.”

Astronomy and beer go together at Bad Jimmy's.

Astronomy and beer go together at Bad Jimmy’s.

We’ve seen the evidence of black holes in other galaxies by catching the glow of gas as it is consumed by supermassive black holes.

“This gas is flowing in, spiraling around, and becoming very, very hot,” Tremmel noted. “As that gas gets really hot it emits a lot of light.”

Tremmel said it’s an exciting time for his field of study, trying to figure out more about the formation of supermassive black holes.

“These relatively tiny objects within a galaxy are a true mystery still for astronomers,” he said.

The next Astronomy on Tap Seattle is scheduled for Wednesday, May 20 at 7 p.m. at Bad Jimmy’s. It’s free, and you can RSVP here.

More reading


Seattle Astronomy calendar, week of May 11

This week the Moon flirts with the two ice giant planets, there’s a star party in eastern Oregon, and we celebrate the anniversary of the opening of the first planetarium in the Western Hemisphere.

Prineville Reservoir Star Party

We’ve been hanging around astronomy types for a while now, but hadn’t heard of the Prineville Reservoir Star Party until stumbling across a notice for it on Facebook recently. This year’s is the 16th annual occurrence of the event, which will be held from 1 p.m. until 11 p.m. Saturday, May 16. It will be at Oregon’s Prineville Reservoir State Park, which is about 15 miles south of the town of Prineville, which is 20 miles east of Redmond, which is 17 miles north of Bend.

Big Doug

A park ranger poses with Big Doug, the Prineville Reservoir State Park’s 16-inch Dobsonian telescope. Photo: Oregon Parks and Recreation.

The park is in an area of marvelous dark skies and park staff promote astronomy there year-round. There will be a variety of astronomy-related exhibits and activities for all ages at Saturday’s star party, and visitors will be able to take a look through the aptly named “Big Doug,” the park’s 16-inch telescope. Solar telescopes will also be available during the day, allowing safe viewing of solar flares on the surface of the sun. Both professional and amateur astronomers will be on hand starting at dusk to help guide viewers in using the different types of telescopes and to point out significant features in the night sky.

The star party is co-sponsored by the Oregon Observatory at Sunriver and the Oregon Parks and Recreation Department. As near as we can tell the star party is free, though there may be a charge for parking.

Happy 85th to Adler Planetarium

Adler planetarium

Astronomical League conventioneers mull about outside the Adler Planetarium in Chicago during a field trip July 4, 2012. Photo: Greg Scheiderer.

The Adler Planetarium opened in Chicago on May 12, 1930, and is said to be the first planetarium in the Western Hemisphere. It celebrates its 85th birthday this week.

We have enjoyed visiting the planetarium during the 2012 Astronomical League meeting, as well as during a layover in the Windy City during a coast-to-coast train trip. It’s a marvelous facility, and I especially enjoyed all of the spaceflight artifacts from Jim Lovell, the Apollo 13 astronaut who is a trustee of the Adler.

The Moon and the ice giants

Venus, Jupiter, and Saturn are all prime for viewing this week. The most interesting observing will involve the Moon and the two ice giant planets. On Tuesday, May 12, Neptune will appear just three degrees south of our planet’s satellite. Three days later, on May 15, there will be an even closer encounter when Uranus will appear just two-tenths of a degree north of the Moon.

You’ll need optical help to spot either planet, especially from light-polluted city skies, though we’ve heard tell that some eagle-eyed observers have been able to spot Uranus with the naked eye. Check out the Seattle Astronomy Store if you’re shopping for telescopes, binoculars, eyepieces, or other astro gear.

The Sky This Week from Astronomy magazine has other observing highlights for the week. Keep an eye on our calendar to stay up to date on Northwest astronomy events.