Category Archives: lectures

Aperture fever strikes in the hunt for dark matter

There’s a truism in astronomy that aperture rules. The wider your telescope mirror or lens the more photons you can capture and the better views you’ll get of celestial objects. It turns out that aperture fever strikes professional astronomers as well as amateurs. The latest to fall victim to this malady is Julianne Dalcanton, professor of astronomy at the University of Washington. Last week Dalcanton gave a talk at the UW titled “Building the Universe Piece by Piece.” It was part of the lecture series The Big Bang and Beyond being presented by the UW Alumni Association in celebration of the 50th anniversary of the university’s Department of Astronomy.


Prof. Julianne Dalcanton spoke about galaxy formation and evolution at the UW Nov. 18. 2015. Photo: Greg Scheiderer.

Dalcanton’s bailiwick is the study of the formation and evolution of galaxies, and she picked up that story where Miguel Morales left off two weeks before in the second lecture of the series. Morales took us up to the “end of the beginning,” the release of the cosmic microwave background, 380,000 years after the Big Bang. Once things cooled down after that, the universe developed more complexity.

“You have intergalactic gas that originally permeated the universe mixed with the dark matter and the light of the cosmic microwave background,” Dalcanton said. “This gas has funneled, along with the dark matter, into these increasingly rich structures and then funneled into galaxies.”

As the galaxies formed, so did stars out of even more densely concentrated areas of gas. Dalcanton noted that the Hubble Space Telescope has given us marvelous photos of stars being born in places like the Orion Nebula or the Eagle Nebula, subject of the now-famous photo “Pillars of Creation.”

Beautiful and deadly


“The Pillars of Creation” is arguably Hubble’s most famous photo. Image: NASA, Jeff Hester, and Paul Scowen (Arizona State University) –

“These scenes of great beauty are scenes of great destruction,” Dalcanton said. “The stars that are born here are the ultimate in ungrateful children. They are just going about their business absolutely destroying the cloud from which they were born.”

Dalcanton pointed out that we can recognize young stars easily because they’re massive, bright, blue, large, and hot. They tend to flame out quickly. On the other hand, smaller, cooler, dimmer red stars like our Sun last a lot longer.

“They all seem so different,” Dalcanton said. “There’s a clear regularity in their properties that must be directly linked to the physics that’s going on inside the stars.”

By looking at other galaxies and noting the distribution of young and old stars, astronomers get clues about how the galaxies evolved and how elusive dark matter works. Then they make computer models and compare the results to what they see around the universe. The theoretical models match the observations pretty well so far.

“Just because you can make it in the computer doesn’t mean that it’s true,” Dalcanton cautioned. “The study of the individual stars and the actual histories of individual galaxies, where we can pick them apart into their individual pieces, gives us a really strong constraint on all of these models. That then gives us the additional leverage to try to break apart various possible theories of dark matter.”

“The key ingredient to all of this is actually detecting individual stars,” she added.

We need a bigger telescope

This is where the aperture fever comes in.

Dalcanton heads up PHAT, the Panchromatic Hubble Andromeda Treasury, a project in which Hubble made nearly 13,000 images of the Andromeda Galaxy and did a billion measurements of 110 million stars. Volunteers in the Andromeda Project helped sift through nearly a terabyte of data, and we learned a lot.

“As awesome as this is, Hubble is not enough,” Dalcanton said. “Hubble’s my babe, but it’s got its limitations.”

She said Andromeda was chosen for this survey because it is the closest, most massive spiral galaxy we can get a good look at.

“Even with the Hubble Space Telescope we can’t really pick apart all of the stars that we actually want to,” Dalcanton said.

HDST is the answer

The HDST would dwarf Hubble or the James Webb Space Telescope, planned for launch in 2018. Image: C. Godfrey, STscI.

The HDST would dwarf Hubble or the James Webb Space Telescope, planned for launch in 2018. Image: C. Godfrey, STscI.

That’s why she’s a big advocate for a new project on the drawing boards called the High Definition Space Telescope (HDST). Hubble’s mirror is 2.4 meters. HDST’s would be nearly 12 meters, and would have 25 times the surface area of Hubble. Dalcanton said that would give it vastly superior sensitivity and clarity.

“We would see fainter stars and we would see them in regions of the universe where they were much more closely packed together,” she said. It would be like going from an old tube TV to your new 60-inch high-definition television. HDST would be strong enough to spot planets orbiting relatively nearby stars, and could see more and more stellar nurseries like the Eagle Nebula.

“We would be able to see those in individual galaxies anywhere in the universe,” with the HDST, Dalcanton said.

“That’s what I’m rooting for.”


The end of the beginning of the universe

Miguel Morales has been spending a lot of time pondering what he calls “the end of the beginning of the universe”—the cosmic microwave background. Morales, professor of physics at the University of Washington, heads up the university’s Dark Universe Science Center, a group working to figure out gravity, dark matter, dark energy, galaxy formation and evolution, and other cosmological mysteries. Morales gave a talk earlier this month titled “The End of the Beginning.” It was the second of a four-part lecture series, The Big Bang and Beyond, sponsored by the UW alumni association in celebration of the 50th anniversary of the Department of Astronomy.


The now-famous rendering of the cosmic microwave background “looks like Pollock. It’s kind of a mess!” jokes Prof. Miguel Morales. Yet it may hold clues to how the universe formed and how we all got here. Image: ESA and the Planck Collaboration.

Morales gave a “Cliff’s Notes” history of the formation of the universe, noting that the end of the beginning came about 380,000 years after the Big Bang, when the hydrogen and helium plasma formed by that event cooled sufficiently to change phase and release light.

“It froze from an opaque helium hydrogen plasma to a clear, neutral gas,” Morales explained.

The “glowing wall of gas” left behind is the cosmic microwave background. Recent measurements have confirmed temperature fluctuations in the CMB.

“These are real, hot and cold spots that we see on the sky,” Morales said. “This is the writing of creation on the wall.”

Ghostly evidence

Morales noted that this writing is extremely faint. He pointed out that the differences between the red an blue sections of the now-famous Planck map of the cosmic microwave background are just one part in 100,000.

Miguel Morales explains how oscillations in plasma created sound waves that can be spotted within the cosmic microwave background. Photo: Greg Scheiderer.

Miguel Morales explains how oscillations in plasma created sound waves that can be spotted within the cosmic microwave background. Photo: Greg Scheiderer.

“This is really a testament to precision measurement,” he said. He noted that, given this level of accuracy, we can learn a lot about what was going on in the early universe from the evidence left behind.

For example, scientists have teased out sound waves from the cosmic microwave background. The waves were created when the plasma oscillated in what was essentially a tug-o-war between gravity trying to collapse the mass and photons resisting that force. How those sound waves propagate could hold clues to what was going on in the early universe.

Changing tactics

The early observations measured temperature, but Morales said the state of the art is to look at the polarization of the light, which could lead to a needle in the cosmic haystack.

“You might be able to see, in the polarization, the ghost of gravity waves from inflation,” he said. They actually thought they had something in observations from the BICEP2 telescope at the South Pole, but what they saw actually turned out to be spinning dust.

“The polarization that BICEP saw is contaminated by the galaxy,” Morales said. “We’re seeing stuff on the windshield here; it’s not all primordial.”

One of the greatest challenges in making these observations is fine-tuning the instruments to ignore the noise and not be faked out by the data.

“BICEP is a technical tour de force, the measurement is awesome. It’s just a little contaminated, and, to be honest, Planck is not sensitive enough to say how bad the contamination is,” Morales explained.

That, he said, is science.

“We’ll keep looking, scratching our heads, building yet more sensitive instruments as we learn to read the words about the universe written faintly on the sky.”


Spooky action explained

Some eighty years ago Albert Einstein derided the notion of quantum entanglement as “spooky action at a distance.” Today, according to author and journalist George Musser, “We’re starting to see the hazy outlines of an answer,” to questions about the how particles in different locations appear to act on each other. He is quick to add that there are still scientists who don’t really believe that non-locality is a real thing.


Author George Musser explains separate particles magically acting on each other during his talk Nov. 3 at Town Hall Seattle. Photo: Greg Scheiderer.

Musser is the author of Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time—and What It Means for Black Holes, the Big Bang, and Theories of Everything (Scientific American / Farrar, Straus and Giroux, 2015). He spoke about the book and the science earlier this month at Town Hall Seattle.

Musser noted that Einstein was clearly bothered by some aspects of quantum mechanics, particularly the notion that randomness governs the universe. This led to his famous observation that God does not place dice.

“It was arguably Einstein’s number one concern,” Musser noted. “His deeper worry, actually the worry that led him to the worry about randomness, was the worry about non-locality. What is non-locality? How can this magic sorcery kind of thing be happening in the real world?”

That’s the quality that got Musser interested in writing about the subject.

“It’s the closest thing that we have in contemporary science to real, honest-to-god, Harry Potter magic,” he said. He noted that it turns up in many different sciences, and isn’t just a “freak show” over in quantum mechanics.

Space is constructed

Muster detailed the experimental evidence that has established that entanglement is a real phenomenon. String theory, loop quantum gravity, and other attempts to explain what’s happening have, at their cores, a similar idea, according to Musser. That idea is that space isn’t just empty and out there; it’s made of something.

“Anyone working on quantum gravity thinks that at some level space is constructed,” Musser explained. “That gives you the opening to deal with non-locality. No longer is that an insoluble puzzle that has been hanging in the air since Einstein’s days.”

Muster suggested thinking about water to illustrate the idea. A single molecule of H2O does not have the properties of water. It’s only when you get a whole bunch of that molecules together that water can flow or have surface tension.

“Likewise, if space consists of atoms, each individual atom is not spacial. Each individual atom lacks the properties we associate with spacial things,” Musser said. “Those spacial properties are derived collectively from the interactions among atoms.”

Given that idea, it’s possible that space can also change its state, just like water can boil and evaporate or freeze, and perhaps that’s part of what is driving our perception of different locations and entanglement.

“It seems that these things are in a predetermined location, but maybe that quality of being in a predetermined location is actively being generated all the time, below our level of consciousness, below the level even of our theories,” Musser said. “There’s some deeper machinery in the natural world.”

It’s a complicated concept to work into a 500-word blog post or a 45-minute lecture. You can listen to an audio recording of Musser’s talk on the Town Hall Seattle website. He is an engaging speaker, and Spooky Action at a Distance promises to be a good read.


Tough choices Wednesday on week’s busy astro-calendar

There are several great astronomy events on the docket for this week. Unfortunately, three of them are at the same time on Wednesday.



The celebration of the 50th anniversary of the Department of Astronomy at the University of Washington continues with another of the lecture series The Big Bang and Beyond. UW astronomy professor Julianne Dalcanton will give a talk titled “Building the Universe, Piece by Piece.” Dalcanton will highlight the unique role that the Hubble Space Telescope has played in shaping our understanding of galaxies and stars as she illuminates the complex forces that have shaped the universe we see around us. She will also talk about the future of space exploration and how it will shape future discoveries about the universe. All free tickets have been claimed for the talk, scheduled for 7:30 p.m. Wednesday, Nov. 18 in room 120 of Kane Hall on the UW campus in Seattle. There will be a waiting list in the event of no-shows.

AOT in the Star Wars spirit

aotnovIf you prefer a little beer with your astronomy head over to Bad Jimmy’s Brewing Company in Ballard Wednesday for another Astronomy on Tap Seattle event. It’s the ninth monthly event in the series, being presented by graduate students from the University of Washington. It’s so popular that Bad Jimmy’s named a brew especially for AoT: the Big Sipper, a Scotch Ale. (It’s yummy.)

This month the topic is planets with two stars. Guest speakers will give brief talks about “How to Find a Tatooine” and “How to Build a Tatooine.” The event is set to coincide with a certain movie release. We’re not sure which one, as they’re not saying. Astronomy, trivia games, prizes, fun, and beer get under way at 7 p.m. It’s free, but RSVP.

SAS takes on photography

saslogoThe Seattle Astronomical Society will hold its monthly meeting Wednesday, Nov. 18 at 7:30 p.m. in room A102 of the Physics/Astronomy building on the UW campus in Seattle. The club’s former president, Denis Janky, will give a talk titled “Astrophotography With a Large Dobsonian Telescope and Color CCD Camera.” Janky is a long-time visual observer who only recently began dabbling with astrophotography. He uses a Mallincam Universe color CCD camera with an Obsession Dobsonian telescope. The Obsession has a tracking system, but is designed for visual observing. The Mallincam has capability for real-time observation on a computer screen and is also a full-fledged color CCD camera. Janky will show his setup and explain how it works.

The club will also hold its election of officers for the coming year.

Eastside Science Café

logo-233x751The Eastside Science Café tackles an astronomy topic this month. Matt Tilley, a Ph.D. student in the UW Astrobiology Program, will give a talk titled “The Magnetospheres of Solar System Planets and Beyond” at 7 p.m. Tuesday, Nov. 17 at Wilde Rover Irish Pub in Kirkland. Tilley will talk about how the Earth’s magnetic field shields us from deadly solar radiation. He’ll look at other planets and discuss how magnetic fields might be used to explore planets light years away.

Science cafés are a program of Pacific Science Center.

Saturday star parties

Both the Seattle and Tacoma astronomical societies plan public events for Saturday, Nov. 21. SAS will hold its free monthly public star parties at Green Lake in Seattle and Paramount Park in Shoreline. Both will get under way at 5 p.m., weather permitting. Tacoma Astronomical Society‘s public night at the Fort Steilacoom campus of Pierce College will begin at 7:30 p.m. with a presentation about the New Horizons mission to Pluto. Telescopes will come out for observing if the weather cooperates.

Track upcoming events on the Seattle Astronomy calendar.


Dark matter may have killed the dinosaurs

Harvard particle physicist and author Lisa Randall has a new hypothesis about what killed the dinosaurs, and it’s a surprisingly simple one. The possible culprit: dark matter.

Lisa Randall

Physicist Lisa Randall spoke at Town Hall Seattle about her hypothesis that dark matter may have triggered the events that killed the dinosaurs. Photo: Greg Scheiderer.

Randall visited Town Hall Seattle last week to talk about her ideas, explained in her new book Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe (Ecco, 2015).

Randall noted that ordinary matter forms into disks like our galaxy and solar system because it interacts with light, radiates photons, cools, and collapses. Dark matter, on the other hand, doesn’t interact with light and so stays diffuse. It is believed that the Milky Way Galaxy sits inside an essentially spherical halo of dark matter.

Here’s where Randall throws in a what-if. The model for dark matter presumes it consists of only one type of particle. But that’s not necessarily so.

“Maybe there’s a new type of dark matter in addition to the dark matter that people talk about,” Randall said.

“Suppose you had dark matter which could radiate,” she speculated. “Maybe dark matter interacts with its own light, which I’m going to call dark light.”

If that’s the case, this particle also could form structure, Randall said.

“Most of the dark matter is going to stay intact in a spherical halo, but this small fraction, maybe five percent of dark matter that interacts with dark light, can also collapse into a disk,” she said. This thin disk of dark matter would be embedded in the plane of the galaxy.

Here’s how that could have been the death blow for the dinosaurs, and a big chunk of the rest of the life on Earth, about 66 million years ago. Randall noted that, as our solar system rotates around the galaxy, it doesn’t follow a simple, flat course.

“As it goes around it actually bobs up and down through the plane of the Milky Way,” every 30 million years or so, she said.

“When it goes through that mid-plane, if there is a dark-matter disk there will be an enhanced gravitational force,” Randall explained. “So our hypothesis is that every time it goes through the mid-plane it can trigger comets getting dislodged from the Oort Cloud, and one of those could have been the comet that actually did in the dinosaurs.”

Randall stresses that this is all highly speculative, but she’s looking for evidence in her current research. She’s hoping to get data to further test the notion from the Gaia satellite, which will make precise measurements of the motions of about one billion stars. That will help us get a better handle on dark matter and where it is.

In the meantime Randall marvels at the interconnectedness of the universe. Galaxies could not have formed without dark matter, yet it may also have set into motion events that wiped out much of the life on our planet, also paving the way for large mammals, like us, to flourish.


Weighing the universe

Astronomers are about to take their best shot at weighing the universe. You might well ask how and why; University of Washington astronomy professor Andy Connolly recently tackled those questions in a lecture titled “Unraveling Our Own Cosmic History.” The talk was the first in a series dubbed The Big Bang and Beyond being sponsored by the UW Alumni Association as part of the celebration of the 50th anniversary of the university’s Department of Astronomy.


Professor Andy Connolly spoke Oct. 21 to kick off the Big Bang and Beyond lecture series celebrating the 25th anniversary of the Department of Astronomy at the University of Washington. Photo: Greg Scheiderer.

The why is easy: to try to figure out dark matter and dark energy. The how, according to Connolly, is actually pretty simple, too: they’re going to weigh the universe by looking at it, and not in a carnival weight-guesser sort of way.

To explain the idea, Connolly used an example of a swimming pool with tiles on its bottom. Water refracts light, and as the surface of the water in the pool ripples the reflections of light on the bottom of the pool move. Similarly, if you watch the grid of tiles on the bottom of the pool, the view will change. Connolly noted that by taking precise measurements of the distortion, we could determine the size of the waves and the mass of the water in the pool. Blow that model up to astronomical scale, about six billion light years, and you can weigh the universe.

Connolly looked, and found no grid in the sky, but notes that there are galaxies everywhere which can serve the same purpose.

“If I can measure the shapes of galaxies, and measure how they’re distorted through gravitational lensing, in the same way that I could measure the mass of the waves on the surface of a pool, I can now measure the mass of the universe,” Connolly said. “More importantly, I can measure that structure as a function of the age of the universe.”

The challenge is that while the structures are huge, they’re also spread out and the distortion will be miniscule. Spotting it will take a better telescope, and that’s one of the research reasons that the Large Synoptic Survey Telescope (LSST) is under construction in Chile. The UW is a founding partner of the LSST, which will have an 8.4-meter mirror and a 3.2 billion pixel camera. Its images will cover 3.5 degrees of sky; the Hubble Space Telescope would have to shoot about 3,000 images to achieve the same results.

“This means that (the LSST) can survey half the sky every three nights,” Connolly said. By comparison, it took the wildly successful Sloan Digital Sky Survey ten years to image a fifth of the sky. In other words, we’re in for a big download of data. Connolly said that the LSST will produce a thousand times more data than did Sloan, which revolutionized astronomy by making so much data publicly available.

The possible discoveries from so much new data are staggering. Connolly noted that data on a mere handful supernovae led to the discovery of dark energy.

“It’s amazing that measuring the distances and the brightness of 42 supernovae could reveal a component of our universe that drives the expansion, a component of our universe that makes up 73 percent of the energy budget in the universe today,” Connolly said.

“With the LSST, in ten years we’ll have 1.2 million supernovae,” he added. “A few tens of thousands of galaxies led to the discovery of dark matter through gravitational lensing. With the LSST we get four billion galaxies.”

If it all works, Connolly said it would help us solve what it perhaps the greatest scientific riddle of our time.

“If we can understand dark energy, if we can understand dark matter, if we can understand how the universe formed in the earliest fractions of a second, then we may be able to unify two of the biggest discoveries in the last hundred years: the discovery of general relativity, which explains gravity and how structure forms; and quantum mechanics, how our universe might have come into being.”


Astro happenings every night this week

There’s plenty to do in Seattle this week for those interested in astronomy, as there is at least one event every evening through Saturday.

Physics week at Town Hall

Town Hall Seattle will welcome two authors to the city this week. Harvard particle physicist Lisa Randall will speak at 7:30 p.m. Monday, Nov. 2, about her new book, Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe (Ecco, 2015). Did dark matter kill the dinosaurs? Randall draws a connection between the Milky Way and the dislodged comet that smashed into Earth 66 million years ago. She’ll describe the ins and outs of this idea, explain what historical galactic events have to say about the present, and, perhaps most importantly, instill a greater appreciation for the interconnectedness of the universe we live in. Tickets, $5, here.

Town Hall will feature more physics on Tuesday, Nov. 3, as journalist George Musser of Scientific American talks about his new book, Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time—and What It Means for Black Holes, the Big Bang, and Theories of Everything (Farrar, Straus and Giroux, 2015). The title is a nod to Einstein’s critique of quantum mechanics, and Musser will look at the universe, black holes, the Big Bang, wormholes, and other somewhat unknown areas of physics. In this month, which marks the centennial of the publication of Einstein’s theory of relativity, he will celebrate today’s best scientific thinking and help us understand it. Musser’s talk will begin at 7:30. Tickets are $5 here.

UW astro anniversary celebration continues



The University of Washington Alumni Association is helping to celebrate the 50th anniversary of the university’s Department of Astronomy with a series of four lectures titled The Big Bang and Beyond: Four Excursions to the Edges of Time and Space. The second in the series will be held Wednesday, Nov. 4 at 7:30 p.m. in room 120 of Kane Hall on the UW campus in Seattle. UW professor Miguel Morales will give a talk titled “The End of the Beginning,” focusing on how scientists read the subtle patterns in the cosmic microwave background to infer what happened in the first few moments of our universe’s history.

All of the free tickets for this lecture, and for the others in the Big Bang and Beyond series, have been claimed. It may be possible to gain admission on a waiting list should there be no-shows. Check our previous post for a rundown of other anniversary events.

Spacefest comes to Museum of Flight

spacefestlogoThe Museum of Flight will host a three-day Spacefest beginning Thursday, Nov. 5 and running through Saturday the seventh. Highlights of the event include astronaut John Herrington leading a glider-building session during the museum’s free-admission evening on Thursday, discussions Friday about the rigors of human spaceflight, and a look Saturday at the challenges of a trip to Mars.

Visit the museum website for a full schedule of the three-day festival.


originsposterThe centerpiece of the UW astronomy anniversary celebration is a multimedia concert, Origins: Life and the Universe, at 2 p.m. Saturday, Nov. 7 at Benaroya Hall in downtown Seattle. Eight Seattle composers have created original orchestral music that showcases the complexity and beauty of our universe. The symphonic concert will be accompanied by projected high-resolution movies created using some of the most spectacular imagery, videos and conceptual art from the Hubble Space Telescope and a variety of other sources. The live concert will feature Grammy-award winning conductor David Sabee and the renowned Northwest Sinfonia orchestra.

Check our previous previews of pieces of the concert, with composers Nan Avant and Glenna Burmer.

The concert is a benefit for scholarships in the UW Department of Astronomy and Astrobiology program. Tickets are $32, $22 for students, and are available through the Seattle Symphony website.

TAS and spectroscopy

The Tacoma Astronomical Society will hold one of its public nights beginning at 7:30 p.m. Saturday, Nov. 7 at the Fort Steilacoom campus of Pierce College. The night will feature a presentation about spectroscopy. In addition, club members will have telescopes on hand should weather conditions be favorable for observing the heavens.

Don’t forget to look up

Venus, Jupiter, Mars, and the Moon are holding a little dance during the mornings all week. Check them out high in the southeast before dawn. The Taurid meteor shower peaks on Nov. 5, but watch out for a few days before and after as well. EarthSky has a good article about watching the Taurids, and Astronomy magazine’s The Sky This Week has daily observing highlights.