Category Archives: astronomy

Welcome, spring, and AoT Seattle this week

It’s a busy week ahead on the area astronomy calendar as four club events, a seasonal observance, and a monthly get-together are on the docket.

AOT Seattle March 24Astronomy on Tap Seattle observes its second birthday this month, and will celebrate with a rare Friday gathering at 7 p.m. March 24 at Peddler Brewing Company in Ballard. The evening’s talks will be a retrospective of the last year and updates of what’s happened in a variety of areas. Topics include gravitational waves, keeping stars weird, exoplanet discoveries galore, the Large Synoptic Survey Telescope, when a star is not really a star, and more! There will be a trivia contest and cool prizes as always. It’s free, but buy a beer or three.

Club events

GottliebThe Rose City Astronomers plan their monthly meeting for 7:30 p.m. Monday, March 20 at the OMSI auditorium in Portland. Guest speaker Steve Gottlieb has a fascinating story to tell. Gottlieb recently completed observing the entire New General Catalogue of Nebulae and Clusters of Stars (NGC for short.) That project took him more than 35 years to finish—the NGC lists 7,840 deep-sky objects!

The NGC was compiled by astronomer John Dreyer in the late 19th century, but there were various errors on between 15 and 20 percent of the objects. Gottlieb will discuss the NGC/IC Project, a joint amateur-professional effort to re-examine the 100 to 200 year-old source material used by Dreyer.

The Eastside Astronomical Society will hold its monthly meeting at 7 p.m. Tuesday, March 21 at the Lake Hills Library in Bellevue. EAS member Tom Hager will continue his look at Burnham’s Celestial Handbook. He’ll focus on the constellations Canis Major and Canis Minor, and the dim constellation Monoceros (the Unicorn) that lies between them. Emphasis of the talk will be on what we’ve learned in the 40 years since Robert Burnham published this classic astronomy reference collection.

The Tacoma Astronomical Society will hold one of its public nights at 7:30 p.m. Saturday, March 25 at the Fort Steilacoom campus of Pierce College. The indoor, all-weather presentation will be about ancient astronomy. If the sky is clear they’ll break out the telescopes for some observing.

The Island County Astronomical Society plans a star party at dusk Friday, March 24 at Fort Nugent Park in Oak Harbor.

Welcome, Spring!

Join Alice Enevoldsen of Alice’s Astro Info to watch the first sunset of spring from Solstice Park in West Seattle. Gather at the park at 6:45 p.m. Monday, March 20 for Enevoldsen’s 32nd seasonal sunset watch. The official charts put sunset at 7:23 p.m., but Enevoldsen has found it’s typically about 10 minutes earlier at that location.

Wrapping Mars Madness

The fourth and final presentation of Mars Madness will be given at 2 p.m. Saturday, March 25 at the Museum of Flight. Guest speaker Dr. Sanlyn Buxner, an education specialist and research scientist from the Planetary Science Institute in Tucson, Arizona, will give a lecture titled, “Mars 201: Mission Accomplished.” Buxner will highlight the outstanding achievements and magnificent failures of more than 40 years of Mars mission science and engineering.

Planetaria

The Washington State University Planetarium in Pullman will run a show titled, “Other Earths” this weekend. The presentation highlights the ongoing search for planets in the Milky Way. How many planets are there? How many could support life? Is there life out there? How much we know might surprise you. Shows are scheduled for 7 p.m. Friday, March 24, and 5 p.m. Sunday, March 26. Tickets are $5 at the door, cash or check—no credit cards.

The Willard Smith Planetarium at the Pacific Science Center in Seattle offers a variety of shows each day. Their complete schedule is featured on our calendar page.

Futures file

Plan your astronomy fun by keeping an eye on our calendar. Recently added items include:

  • Astronomy night at Shorecrest High School in Shoreline April 4
  • Table Mountain Star Party registration opens April 1
  • Battle Point Astronomical Association’s next planetarium shows April 8
  • Astronomy Day at the Museum of Flight May 4

You can also learn of events from our postings on Facebook and Twitter.

Up in the sky

Saturn slides up close to the Moon in the predawn hours on Monday. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope offer more observing highlights for the week.

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Causing mayhem and mass destruction in the Universe Sandbox

If you’ve ever wondered what would happen if the Sun somehow vanished from the solar system, or wanted to watch planets smash into each other, or thought it would be fun to bombard the Moon with asteroids, you’re in luck! You can do all of those things and more with a computer game called Universe Sandbox2. Dan Dixon, creator of Universe Sandbox2, gave a demonstration of it at this week’s meeting of the Seattle Astronomical Society.

“It is software that allows you to ask fantastical questions about the universe and see plausibly true answers,” Dixon said.

Universe Sandbox2 sells for $25.

The possibilities are vast. The slogan for Universe Sandbox2 is “create & destroy on an unimaginable scale,” and the software delivers. It lets users tinker with an incredible number of variables, from the mass and density of objects to the chemical makeup of their atmospheres. Eliminate all of the carbon dioxide and see what happens! Move the Moon in closer to Earth and watch the chaos. For all of the interesting science questions it can answer, Universe Sandbox2 also appeals to our inner 12-year-old.

“People like to collide things,” Dixon noted, and clearly he is one of those people.

“It’s a physics simulation, so in addition to doing interesting things with orbits, you can also do interesting things with collisions,” he added.

Universe Sandbox screenshot

Screenshot from Universe Sandbox2 of an object colliding with Earth.

Those mash-ups got a lot of oohs and aahs from the attendees at the meeting at the University of Washington. It was fun to see what Earth would do to the ring system if it were placed in orbit around Saturn. (Spoiler alert: Disruptive!) Dixon raced through dozens of scenarios, and that only scratched the surface.

He said the results shown in Universe Sandbox2 are “plausibly” true because they have to make some compromises. They don’t simulate every object or every particle out there because that would take way too much computer oomph.

Plausibly true

“It’s a very simplistic simulation; we’re not doing any pressure waves or dark matter,” Dixon said, “but it still is pretty cool.”

So when Mars smacks into Earth in an attempt to see if a new moon would result, you don’t necessarily have all of the data you would like.

“You really would want to have like a billion pieces,” Dixon said, but “because we’re trying to do this real time on modern-day desktops or laptops, you can’t have as many pieces as you want and get it still to run in real time.”

“We’re undoubtedly wrong in a lot of cases, and there’s a lot of room for improvement in the simulation,” Dixon noted. They’re revamping the way the program handles stellar evolution and are working to improve planetary climate simulations. Part of the challenge is that they’re often simulating events for which there is not yet a scientific answer.

“We’re trying to solve things that are not well-defined or understood,” Dixon said. That’s not to say they’re just making stuff up.

“Being realistic is really important to me,” Dixon said, but they want to let users come up with their own crazy scenarios. “One of the goals of the software is to allow ridiculous premises but then carry that to a realistic conclusion.”

Humble beginnings

In a way, Universe Sandbox2 has been in development for 20 years. When Dixon was in middle school his father downloaded a simple gravity simulator from a BBS list. (Remember those?) It didn’t have many features, but it caught Dixon’s interest.

“I’ve always been fascinated with the motions of gravity,” he said, “and gravity is a really simple formula, too. It’s always fascinating how this really simple formula can do these really beautiful and organic interesting motions.” Later on in middle school Dixon coded his own simulator. He’d tinker with it every once in a while, then became serious about it about ten years ago.

“This was not like the grand ambition. It was a thing I was working on for fun, and now it’s turned into this crazy thing,” Dixon said. “What started as a personal side project is now what myself and eight others do full time.”

“I think if I had a time machine and I went back and showed my younger self what it’s become, I would have been overwhelmed and wouldn’t have started on it,” he laughs.

“This is a passion project that I’m fortunate enough to continue working on.”


View the Universe Sandbox2 teaser below. Purchasing through this link supports not only Universe Sandbox2 but also Seattle Astronomy in our efforts to tell interesting stories.

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Pi Day, Mars Madness, and more this week

Pi Day, Mars Madness, planetarium shows galore, and astro club events fill a busy calendar this week.

Pi Day

Celebrate Pi Day at 5 p.m. Tuesday, March 14 at the Pierce College Science Dome. This free celebration will include hands-on math and science activities, a pi recitation typing contest, and Chaos and Order: A Mathematical Symphony. Please reserve seats in advance for the symphony, which will run at 5 p.m., 6 p.m., and 7 p.m. in the dome. Reservations are not needed for the other activities.

MOF Mars Madness

Phoenix landerMars Madness continues at the Museum of Flight at 2 p.m. Saturday, March 18. This week’s presentation will feature the museum’s Carla Bitter, former education and public outreach manager of NASA’s Phoenix Mars Lander mission, who will give a family friendly, fast paced Mars 101: Know Your Missions presentation, complete with Red Planet prizes. Mars Madness is happening every Saturday in March, and is free with museum admission.

Club meetings

The Olympic Astronomical Society will hold its monthly meeting at 7:30 p.m. Monday, March 13 in room Engineering 117 at Olympic College in Bremerton. A guest speaker will talk about the Moon. Mysteriously, the club website doesn’t list who the speaker will be. Is it a major Moon celebrity?

The Seattle Astronomical Society plans its monthly meeting for 7:30 p.m. on the Ides of March—Wednesday, March 15—in room A102 of the Physics/Astronomy building on the University of Washington campus in Seattle. Guest speaker Dan Dixon, creator of the Universe Sandbox simulation game, will talk about how he and his team of programmers, a planetary scientist, and a climate scientist collaborated to create an app that can model galactic collisions and solar system dynamics.

Planetarium shows

Check out The Secret Lives of Stars, a free show at the Bellevue College Planetarium that will play at 6 p.m. and repeat at 7 p.m. on Saturday, March 18. Reservations are recommended; information about reservations, parking, and location is online.

The Willard Smith Planetarium at the Pacific Science Center offers a variety of programs every day. Check their complete lineup on our calendar page.

Futures file

You can scout out future astronomy events on our calendar. We’ve recently added:

Up in the sky

Jupiter, Spica, and the Moon will form a nice triangle in the evening on Tuesday. The Sky This Week from Astronomy magazine and This Week’s Sky at a Glance from Sky & Telescope offer more observing highlights for the week.

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Astro Biz: Orion buses

Orion busesMany 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 buses. Based in Mississauga, Ontario, Orion manufactured transit buses from 1975 until 2013. King County Metro Transit continues to operate a number of Orion buses; this Wikipedia article says that Metro purchased 199 of them between 2010 and 2012. There have been suggestions that posts supporting the windshields of these buses create blind spots that may make it more difficult for bus drivers to spot pedestrians.

We chose Orion this week because the constellation of the hunter is high in the south as darkness falls these days. Wait for a clear night and a view of the Orion Nebula in his sword.

More info:

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The expanding universe: discovery, controversies, and hope

We’ve known that there is a universe outside the Milky Way, and that it is expanding, for less than a century.

“Throughout the entire history of the universe, of knowing it’s expanding, there have been a tremendous number of controversies over it, and there’s still one that persists today,” said astrophysicist and author Ethan Siegel. Siegel, author of Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific Publishing, 2015), spoke at last week’s meeting of the Rose City Astronomers in Portland, Oregon.

The controversy actually goes back to before the expansion was observed, to Albert Einstein. His equations describing general relativity suggested that gravity would collapse the universe onto itself, and as he believed the universe was static, he threw in a “cosmological constant” to push back against gravity. Einstein later called that his biggest blunder, though some wanted to let him off the hook for it when dark energy was proposed to do the exact same thing.

“I am here to tell you that this was Einstein’s reasoning and throwing this in there when he did was a super big blunder because the universe isn’t static,” Siegel said. Einstein should have trusted his theory, he said, and taken it to the next step.

The universe is expanding

By the 1920s Edwin Hubble observed a Cepheid variable star in the Andromeda “nebula” that indicated that it was far outside the Milky Way and a galaxy in its own right. Astronomers were also studying redshift as an indication for the speeds at which galaxies were receding from us. Siegel explained that through this, Hubble determined that the universe was expanding at a rate of 600km/sec/Mpc (kilometers per second per megaparsec.) This became the Hubble constant. But it wasn’t so constant.

Siegel noted that, knowing the size and expansion rate of the universe, you can figure its age by running the numbers in reverse and going back to the beginning, to the Big Bang. The resulting calculation determined that the universe was about two billion years old. Geologists at the time had already pegged the age of the Earth as at least four billion years.

“This was a problem for Hubble, because the universe isn’t allowed to be half the age of the Earth,” Siegel noted. “Either this expansion rate is wrong and this age for the universe is wrong, or the age of the Earth is wrong.”

It turns out that Hubble’s main mistake was in figuring that all variable stars are alike. Siegel said Walter Baade came along in the 1940s and discovered that they are not. Finding that most of the Cepheids Hubble had looked at were non-classical, they re-ran the numbers from Hubble’s data.

“As you accumulate more knowledge, as you accumulate a better understanding of what you’re actually loooking at, you can go back and get more useful science out of this data,” Siegel said. This second look doubled the distance to these stars and reduced the value for the Hubble constant to 270km/sec/Mpc. This in turn put the age of the universe at five billion years.

“That’s better,” Siegel noted. “The universe is older than Earth. That’s one problem solved.”

Narrowing it down

Siegel

Dr. Ethan Siegel, creator of the “Starts With a Bang” blog, gave a talk about the age and size of the universe to the Rose City Astronomers February 20. Photo: Greg Scheiderer.

As time went on astronomers developed the “distance ladder” for determining the vast distances in the universe. You first measured the distance to Cepheid variables within the Milky Way, then gauged the distances to other galaxies using Cepheids spotted there. Type 1a supernovae could be spotted really far out. As we learned more about the stars we got a little better at figuring distances.

Things got really interesting in the 1960s, according to Siegel. We discovered that we could determine the ages of stars by measuring their color and brightness. The Hertzsprung–Russell diagram told us that the oldest stars were between 14 billion and 16 billion years old, significantly older than the age of the universe determined by Baade. Astronomer Allan Sandage, who as a graduate student was an assistant to Hubble, came along and said you needed two things to make the universe that old: it had to be low enough in density to make a vast expansion, and the expansion rate had to be low.

Dueling Hubble constants

This, Siegel said, was where the controversy came in. Sandage said the expansion rate would have to be between 50-60km/sec/Mps. Rival astronomer Gérard de Vaucouleurs of France put it at around 100km/sec/Mpc. The race was on to make observations to see which group was right. Amazingly enough, each group’s observations matched up with what they thought the answer would be.

“This just goes to show that you cannot have the same people making the same measurements and trust them,” Siegel said. “This is why you need independent confirmation.”

It turns out Sandage and de Vaucouleurs were both wrong. There’s still no agreement on the right answer, but the disagreements are getting closer together. Sigel said the Hubble Space Telescope’s improvements in measuring the size of the universe return a value of 74±2km/sec/Mpc. The Planck mission’s observations of the cosmic microwave background radiation suggest 67±1km/sec/Mpc.

“There is a fight over the results like there always seems to be, because we are scientists and we cannot agree on anything,” Siegel said. “That is good, because questioning is what keeps us moving forward and what keeps us learning more.”

“The way we’re going to get there is with more and better data,” he added.

Better data

The better data will come from missions such as the European Space Agency’s Gaia, the James Webb Space Telescope, WFIRST, and the Large Synoptic Survey Telescope, which combined might improve our parallax measurements of cosmic distances by a factor of ten. We might also weed out faulty assumptions in the earlier work or get more accurate insights into the balance between matter and dark energy in the universe.

“If we can wait until the next decade, we might see that 74 number come down, we might also see the 67 number come up,” Siegel said. “The point is uncertainties are going to be reduced by more and better data.”

Siegel said that right now it’s pretty much agreed that the universe is about 13.8 billion years old and consists of about 30 percent matter and 70 percent dark energy. But the miniscule pluses or minuses can lead to huge fights.

“When that data comes in at last we will know exactly how fast our universe is expanding, how old it is, and what it all means for both our cosmic origins and our cosmic fate,” Siegel concluded. “That’s pretty good stuff.”


In the podcast linked below Siegel covers much of the topic matter of this article and his talk. His new book, Treknology: The Science of Star Trek from Tricorders to Warp Drive (Voyageur Press, 2017), is scheduled for release in October.

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Search for meaning continues

There is a great menu of interesting talks on this week’s calendar, including three with astronomy themes at a weekend event at Seattle University.

Search for Meaning FestivalSeattle University’s annual Search for Meaning Festival will be held on the university campus all day Saturday, February 25. The festival is a community event dedicated to topics surrounding the human quest for meaning and the characteristics of an ethical and well-lived life. It draws more than 50 authors and artists who will give interactive presentations. Three of these sessions are on astronomy-related topics.

At 9 a.m. Father George Coyne, SJ, former director of the Vatican Observatory and author of Wayfarers in the Cosmos: The Human Quest for Meaning (Crossroad 2002), will discuss the history of the evolution of life in the cosmos. Coyne’s thesis is that this history may lead us to a deeper understanding of what many secular physicists say themselves about the cosmos: that a loving creator stands behind it.

At 10:45 a.m. Margot Lee Shetterly, author of the book Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race (William Morrow, 2016), on which the current hit film is based, will give one of the keynote addresses at the festival. Shetterly will talk about race, gender, science, the history of technology, and much else. Reservations for Shetterly’s talk are sold out.

At 12:45 p.m. Marie Benedict, author of The Other Einstein (Sourcebooks Landmark, 2016), will explore the life of Mileva Maric, who was Albert Einstein’s first wife and a physicist herself, and the manner in which personal tragedy inspired Mileva’s possible role in the creation of Einstein’s “miracle year” theories.

Check our post from December previewing the festival, and look at the trailer video below. Tickets to the festival are $12.50 and are available online.

Siegel at Rose City

Author and astrophysicist Ethan Siegel will be the guest speaker at the monthly meeting of the Rose City Astronomers in Portland at 7:30 p.m. Monday, February 20. Siegel will talk about his book Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific Publishing, 2015). He’ll examine the history of the expanding universe and detail, up until the present day, how cutting-edge science looks to determine, once and for all, exactly how the universe has been expanding for the entire history of the cosmos. Siegel is an informative and engaging speaker; check our recap of his talk from last year about gravitational wave astronomy.

AoT Seattle and an app for simulating the universe

AoT FebruaryAstronomy on Tap Seattle’s monthly get-together is set for 7 p.m. Wednesday, February 22 at Peddler Brewing Company in Ballard. Two guest speakers are planned. Dan Dixon, creator of Universe Sandbox² will give an introduction to the app, an accessible space simulator that allows you to ask fantastical what-if questions and see accurate and realistic results in real-time. It merges real-time gravity, climate, collision, and physical interactions to reveal the beauty of our universe and the fragility of our planet. University of Washington professor in astronomy and astrobiology Rory Barnes will talk about “Habitability of Planets in Complicated Systems.” It’s free, except for the beer.

TAS public night

Tacoma Astronomical SocietyThe Tacoma Astronomical Society plans one of its public nights for 7:30 p.m. Saturday, February 25 at the Fort Steilacoom campus of Pierce College. The indoor presentation will be about the zodiac. If the skies are clear they’ll set up the telescopes and take a look at what’s up.

Futures file

You can scout out future astronomy events on our calendar. We’ve recently added several events scheduled at the Museum of Flight, including:

Up in the sky

There will be an annular solar eclipse on Sunday, February 26, but you’ll have to be in South America or Africa to see it. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy offer more observing highlights for the week.

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Threading the needle with Cassini at Saturn

The hugely successful Cassini mission to Saturn will come to a fiery end in September, and you can hardly blame NASA for going a little Star Trek on us.

Ron Hobbs

Ron Hobbs. Photo: Greg Scheiderer.

“We’re going somewhere where no spacecraft has ever gone before, into this region between the glorious rings of Saturn and the cloud tops of the planet,” said Ron Hobbs, a NASA Solar System Ambassador, at this month’s meeting of the Seattle Astronomical Society. After 22 orbits through the eye of that needle—a 2,500-kilometer-wide gap—they’ll splat Cassini into the planet and burn it up.

“Now that we’ve discovered that there’s at least one moon, and maybe several, that could have the conditions for life, it’s very important to not leave a derelict spacecraft orbiting around Saturn,” Hobbs noted. “One of the important things at the end of the solstice mission will be to dispose of the spacecraft.”

The second extended mission of Cassini was named solstice because it is almost the beginning of summer in Saturn’s northern hemisphere.

Let’s do science

Before they crash Cassini, they figured there was some time to do some great science in that place where no spacecraft has ever gone. Most importantly, they will get a better picture of the internal structure of Saturn and examine its ionosphere, inner radiation belts, and auroral region.

“This would have been worth sending a spacecraft to Saturn for just that measurement,” Hobbs said, noting that it is essentially what Juno is doing at Jupiter. They’ll also check out the particles of Saturn’s D ring at close range, and be able to better gauge the mass of the ring system, which will help pin down its age.

“I can’t wait for the pictures,” Hobbs added. “The pictures that come out of this mission are just going to be spectacular.”

Shooting the gap

Hobbs said NASA has been using interactions between Cassini and Saturn’s moon Titan to nudge the spacecraft’s orbit to where they want it to be.

“Titan is really the only object in Saturn orbit that has enough mass to allow it to do gravitational assists and re-direct its orbit,” he said. “That allows [Cassini] to change its orbit and change the plane of its orbit.”

Cassini orbits

This graphic shows the closest approaches, or periapses, of Cassini’s final two orbital phases.The ring-grazing orbits are shown in gray; grand finale orbits are shown in blue. The orange line shows the spacecraft’s final plunge into Saturn. Credit: NASA / Jet Propulsion Laboratory – Caltech

In late November a brush with Titan dropped Cassini’s perichron—the point closest to Saturn in its orbit around the planet—down to just outside the F ring. In April, another Titan flyby will drop that perichron down to between the D ring and Saturn’s cloud tops.

“That’s when it’s going to get really exciting,” Hobbs said. Cassini will do 22 “grand finale” orbits through the eye of this needle, each lasting six days, collecting science data until one final encounter with Titan puts the spacecraft on a trajectory to splat into the planet on September 15.

It’s amazing how much planning and politics went into all of this. Hobbs said the actual trajectories of the orbits for this grand finale were determined a little over three years ago. Ever since then there’s been a spirited discussion between scientists, engineers, and mission leaders about what science to do to get as much data as possible out of the final mission. That determination was just completed last month.

“The spacecraft drivers are now writing the code for these orbits,” Hobbs said. That will tell Cassini where to go and where to point its instruments to make the observations as planned.

A good ride

Hobbs noted that Cassini was launched in October 1997, and so will end its mission just shy of twenty years in space.

“Without a doubt it has been one of the most successful and audacious missions NASA and the international community have operated,” he said. “This is going to be one of the highlights of space exploration in the last couple of decades.”

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