Learning about LIGO at Astronomy on Tap

The most recent gathering of Astronomy on Tap Seattle brought to town two scientists working in one of the most groundbreaking areas of astronomy: detection of gravitational waves.

Nature was kind to us

Jeff Kissel, a control systems engineer at the LIGO Hanford Observatory, talked about how exciting it was when they switched on advanced LIGO back in September 2015.

“Boom! Right out of the gate we saw this whopper of an event,” Kissel said, detecting gravitational waves from the merger of a pair of stellar-mass black holes. “Nature was very kind to us.”

What they spotted at Hanford and at LIGO in Livingston, Louisiana was a match.

“Inside our data, which is almost always noise, we saw this very characteristic wave form that was predicted by general relativity,” Kissel recalled. They found gravitational waves from a couple of other black-hole mergers in the following months.

“This is the beginning of gravitational wave astronomy,” Kissel said.

Gravitational waves oscillate through spacetime in a way
by this animation. Credit: ESA–C.Carreau

Kissel pointed out that LIGO only detects a small part of the gravitational wave spectrum. As with light, gravitational waves can come in a wide range of wavelengths with periods ranging from milliseconds to billions of years. Longer-length waves might come from the mergers of galactic nuclei, or even from quantum fluctuations from the early universe.

“There’s a whole zoo of things to find out there,” Kissel said. He anticipates more ground-based observatories as well as some space LIGOs that could have detector arms millions of kilometers long.

How LIGO works

LIGO sounds awfully complicated, but, broken down, the idea is pretty simple. Jenne Driggers
is a Caltech postdoctoral scholar stationed at the LIGO Hanford Observatory, where her gig is improving the sensitivity of the interferometers. Driggers explained that, essentially, they shoot a laser beam into a splitter that sends beams down two equal arms four kilometers long. The beams reflect from mirrors and return to be put back together.

A simplified look at how LIGO works. A laser beam is split and sent down two equal
arms four kilometers long, then reflected back by mirrors. When they return to be
recombined, they will usually cancel each other out and no light will get to the detector.
But if a gravitational wave distorts the system, the light will be spotted by the detector.
Credit: T. Pyle, Caltech/MIT/LIGO Lab

“When they recombine they can be exactly out of phase, and then there’s no laser light (at the detector),” Driggers said. “They cancel each other out totally. Or the lengths will change and these two electromagnetic waves can add up, and so we do get some light.”

When that happens it means that a gravitational wave has distorted the LIGO arms ever so slightly. They measure the light received at the detector to learn more about the wave.

In practice it’s a lot more complicated. It all happens in a total vacuum to avoid any distortion from air. The mirrors are suspended from a system of four pendulums, which helps to eliminate vibration. The mirrors are highly reflective pieces that each weigh around 100 pounds and cost half a million dollars. The laser is about the best there is.

“The laser wavelength itself is our ruler that we’re using to measure the distance between those two mirrors,” Driggers said, “and we need to be able to measure that distance to 10-19 meters.”

“This is one of the highest-power, frequency stable, power-stable lasers on the planet,” she added.

Driggers invited people to tour LIGO Hanford. Public tours are held twice each month, and groups of 15 or more can arrange for a private tour.

Up next: LSST

Astronomy on Tap Seattle is presented and organized by astronomy graduates students at the University of Washington. Their next event is planned for Friday, October 28 at Peddler Brewing Company in Ballard and will feature UW scientists Dr. John Parejko and Dr. David Reiss, who are working on the Large Synoptic Survey Telescope project. The events are free. Enjoy beer and astronomy!


Astro Biz: Orion primitivo

Li Vieli OrionMany businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is Orion primitivo, a wine from Masseria Li Veli winery in the Solento region of Apulia in Italy. According to the Li Veli website, Orion is also the name of a road near the vineyards. The road was once considered to be the border between the Longobards domains to the north and the Byzantium region to the southeast.

We chose Li Veli Orion as the Astro Biz this week in honor of the peak of the Orionid meteor shower, meteors of which appear to originate from the constellation Orion.

More info:


Get the scoop on SpaceShipOne

A lesson on how to make a spaceship and several astronomy club events highlight the local calendar for the coming week.

Road to SpaceShipOne

Meet the principals in XPRIZE-winning SpaceShipOne project at 5:30 p.m. Monday, October 17 at the Museum of Flight. Author Julian Guthrie will discuss her book about the XPRIZE competition, How to Make a Spaceship: A Band of Renegades, an Epic Race, and the Birth of Private Spaceflight (Penguin Press, 2016). Three of the renegades will join her as Geekwire science correspondent Alan Boyle moderates a panel discussion including XPRIZE founder Peter Diamandis, co-founder Erik Lindbergh, and Dave Moore, project manager for Paul Allen on the XPRIZE-winning SpaceShipOne.

The evening will include a meet-and-greet reception from 5:30 until 6:30, Guthrie’s presentation at 6:30, the panel discussion at 6:45, and a question-and-answer session and book signing from 7:30 until 8:30. Cost is $10 and tickets are available online.

You can pick up a copy of the book at the link above or by clicking the image of the book cover.

Astro club events

Michael BarrattThe Rose City Astronomers will hold their monthly meeting at 7:30 p.m. Monday, October 17 at the Oregon Museum of Science and Industry in Portland. The guest speaker will be astronaut Michael Barratt, who spent 199 days in space as flight engineer for International Space Station expeditions 19 and 20 in 2009 and also flew on STS-133, the final flight of the shuttle Discovery, in 2011. Barratt is a native of the Portland area.

The Eastside Astronomical Society will hold its monthly meeting at 7 p.m. Tuesday, October 18 in the Willard Geer Planetarium at Bellevue College. Patti Terhune-Inverso, an astronomy instructor at the college and a member of Eastside Astronomical Society, will present the introduction to the constellations that she uses for her classes at the beginning of each quarter.

The Seattle Astronomical Society will hold its monthly meeting at 7:30 p.m. Wednesday, October 19 in room A102 of the Physics/Astronomy building on the University of Washington campus in Seattle. The program had not been published as of this writing.

Astronomy in Pierce County Saturday

Pierce College will host a couple of events at its Fort Steilacoom campus on Saturday, October 22.

haunted-night-skySpook-tober continues at the Pierce College Science Dome, which will be presenting a kids’ show called “Haunted Night Sky” on Saturdays through Halloween. Participants will be able to find creatures in the night sky, build a Frankenstein satellite, and take a tour of the Sea of Serpents on the Moon, the Witch’s Head Nebula, and other spooky places in the universe. Best for kids ages 3-12. Shows are scheduled for 12:30 p.m. and 2 p.m. each Saturday. Cost is $3.

The Tacoma Astronomical Society plans one of its public nights for Saturday evening at 7:30. The indoor program will be a Halloween special. They’ll break out the telescopes for observing if the weather cooperates.

Futures file

You can scout out future astronomy events on our calendar. New additions to the calendar this week include a talk by astrophysicist Priyamvada Natarajan at Town Hall Seattle November 14. Natarajan will talk about her new book, Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos (Yale University Press, 2016). Tickets are $5 and are available online.

Up in the sky

The Orionid meteor shower peaks this Friday and Saturday. Learn about the showers and other observing highlights for the week by visiting This Week’s Sky at a Glance by Sky & Telescope magazine and The Sky This Week by Astronomy.


Astronomy tourism in Wisconsin

Mention Wisconsin to someone and their first thought might have something to do with cheese, bratwurst, or the Green Bay Packers. I’d suggest adding stargazing to the list after learning of some great resources during a recent trip to Milwaukee. I paid a visit to the Milwaukee Public Museum, where the The Daniel M. Soref National Geographic Dome Theater & Planetarium has just been upgraded to a Digistar 6 computer projection system.

Cool planetarium shows

I saw the museum’s planetarium show titled, “Did An Asteroid Really Kill the Dinosaurs?” It was a visually stunning show that left one feeling that T-Rex and the killer asteroid were actually in the room.

Soref Theater and Planetarium“We produced that, we wrote it, and put it up on the dome, and that’s because we had a big dinosaur exhibit,” explained Bob Bonadurer, director of the theater and planetarium, who added that they create many of their own original programs. He noted that the answer to the question in the show’s title is yes—for now.

“There’s lot of debate about volcanic eruptions possibly contributing to the death of the dinosaurs,” Bonadurer said. “Science always changes with new evidence, and we point that out at the end of the show.”

“Did An Asteroid Really Kill the Dinosaurs?” has since closed, but the planetarium is running two other astronomy-related shows along with its staple “Wisconsin Stargazing,” which looks at what’s up in the sky each month.

Bonadurer said its not all that common to find a planetarium that also has 2D and 3D movies.

“A lot of planetariums stand alone,” he noted. “Our planetarium is part of the big dome theater.”

The recent upgrade has brought even brighter, sharper resolution to the screen.

“With the astronomy software we’ll be able to take the audience on much more engaging trips throughout the cosmos,” Bonadurer said.

Stargazing in Wisconsin

Wisconsin StargazingMilwaukee and Wisconsin have active amateur astronomy communities. There are a half dozen astronomy clubs in the greater Milwaukee area, and the Astronomical League lists 14 affiliated clubs in the state.

“Those astronomy clubs are great to work with,” Bonadurer said. “They help us out with events such as eclipses, and, for example, the Mercury transit back in May.”

As with any big city, Milwaukee has problems with light pollution, but Bonadurer said there’s plenty of good stargazing to the north of town. Newport State Park, about 90 miles north-northeast of Green Bay, is a candidate for International Dark-Sky Park status with the International Dark-Sky Association.

“Like any metro area, we tell our planetarium audiences yes, take the drive, 40-50 miles, get away from the street lights,” Bonadurer said. “It’s a tall order, but do it because it’s worth it.”

“Planetarium skies are nice, but they obviously don’t hold a candle to the real sky,” he added. “We want people to get out there under the real sky.”

Total solar eclipse

Next August 21, when a total solar eclipse crosses the United States, Milwaukee will see the Sun obscured by just 85 percent. The Milwaukee Public Museum will offer programs to help people safely view the partial eclipse in town, and is also sponsoring a five-day eclipse road trip to get people into the totality.

Bob Bonadurer

Bob Bonadurer. Photo: Twitter.

“We’ve got our hotel rooms booked as a lot of planetariums or astronomers do,” Bonadurer said. “We’re usually on the leading edge of all this in getting the public excited.”

Bonadurer, who has seen four total eclipses of the Sun, will lead the tour, which will be able to take about 110 people to the eclipse.

“This will, I hope, reignite a little passion about eclipses in America, because it’s been a long time,” he said. “It’s the first one to sweep across America in 99 years, because for the one in ’79, only a small portion of America got to see it.”

Yerkes Observatory

Astronomy buffs visiting Wisconsin will also want to check out the historic Yerkes Observatory about 50 miles southwest of Milwaukee in Williams Bay, Wisconsin. The observatory, often called the birthplace of modern astrophysics, was founded by George Ellery Hale and has been the research home of Edwin Hubble and a veritable who’s who of astronomers. Check out our article about a visit to Yerkes during the 2012 Astronomical League Conference.

Bonadurer offers this advice to stargazers in Wisconsin and everywhere:

“Keep looking up, see that eclipse,” he suggests. “Get away from the street lights and enjoy this incredible universe.”

Podcast of our conversation with Bob Bonadurer:


Astro Biz: Star Sushi

Star SushiMany businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is Star Sushi in Ashland, Oregon. We spotted the restaurant walking around downtown Ashland during our recent visit to attend the Oregon Shakespeare Festival.

We were unable to find an online presence for Star Sushi except for an unofficial Facebook page. The restaurant apparently has a sister sushi bar in Medford, Oregon. They receive generally decent reviews.

More info:


Astronaut visit a hot ticket this week

An astronaut visit to Seattle is the highlight of this week’s area astronomy calendar, but if you don’t have a ticket already you may be out of luck.

Spaceman: An Evening With Astronaut Mike Massimino will be happening at 5:30 p.m. Friday, October 14 at the Museum of Flight, but as of this writing the event is sold out. The evening’s events include a reception, lecture, and signing of Massimino’s new book Spaceman: An Astronaut’s Unlikely Journey to Unlock the Secrets of the Universe (Crown Archetype, 2016). Massimino is a veteran of two space shuttle missions, including the final servicing mission to the Hubble Space Telescope. If you’d like to go to Friday’s event, you might watch the museum’s website in case additional tickets become available or a waiting list is established. You can pick up the book, at least, at the link above or by clicking the photo at left.

The Boeing Employees’ Astronomical Society will hold its monthly meeting Thursday, October 13, with social time starting at 6:30 p.m. and the evening program beginning at 7 p.m. The meeting will be held in the Boeing “Oxbow” Recreation Center, Building 9-150, Room 201. Non-Boeing attendees are welcome but will need an escort; visit the website for details.

haunted-night-skyIt’s Spook-tober at the Pierce College Science Dome, which will be presenting a kids’ show called “Haunted Night Sky” on Saturdays through Halloween. Participants will be able to find creatures in the night sky, build a Frankenstein satellite, and take a tour of the Sea of Serpents on the Moon, the Witch’s Head Nebula, and other spooky places in the universe. Best for kids ages 3-12. Shows are scheduled for 12:30 p.m. and 2 p.m. each Saturday. Cost is $3.

Futures file

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

Up in the sky

Eagle-eyed early birds can spot Mercury and Jupiter together in the east just before dawn on October 11. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope have more observing highlights for the week.


Astro Biz: Swimming Stars Plaza

dsc_0081Many businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is the “Swimming Stars Plaza” art installation by Lezlie Jane in West Seattle’s Whale Tail Playground. “Swimming Stars” depicts the constellation Cetus, often called the sea monster or the whale; thus Whale Tail Playground (which is actually at the north end of Alki Playground near the intersection of SW Lander Street and Marine Avenue SW) is a fitting spot. Glass stars in the concrete mark the shape of the constellation, and other marine critters linger about as mosaics or imprints as well, and there’s a big octopus on the scene. Click the photo above to get a bigger version!

Cetus is the vehicle in a great story of mythology, sent by Poseidon in revenge for an insult when Cassiopeia, wife of King Cepheus of Ethiopia, claimed to be more beautiful than the Nereids. An oracle told Cepheus that he could stop the sea monster from ravaging his coast by offering up his daughter Andromeda as a sacrifice. Fortunately for her, the hero Perseus happened by and saved Andromeda in the nick of time!

The constellation Cetus is visible in the sky from the site of the “Swimming Stars” installation just four months out of the year, starting in October when you can see it in the south at around 10 p.m. Show up about an hour earlier each month through January to spot it.

This is the third work of art by Lezlie Jane to be featured on Seattle Astronomy. The others are Constellation Park and Luna Girls.

More info: