Category Archives: lectures

CSI Universe: Unraveling the mysteries of Tabby’s Star and supernovae

The universe is full of mysteries; that’s one of the reasons that astronomy is so interesting! We dug into a couple of puzzling phenomena at the most recent gathering of Astronomy on Tap Seattle at Peddler Brewing Company in Ballard. The session was dubbed “CSI: Universe,” and Brett Morris, one of the co-hosts of Astronomy on Tap Seattle and a Ph.D. candidate at the University of Washington, gave a talk about the star KIC 8462852, more commonly called Tabetha Boyajian’s star, thank goodness. His talk was titled, “The Weirdest Star Gets Weirder.”

You helped

Citizen scientists were the first to notice that there was something odd about Tabby’s Star. The Kepler Space Telescope was searching for exoplanets by watching for slight but regular dips in a stars brightness, a possible indication of a planet in orbit around a distant star. Morris noted that it can be difficult to write a computer algorithm to filter out noise in the data, so they enlisted the help of the public through the website PlanetHunters.org.

Brett Morris

Brett Morris (Photo: Greg Scheiderer)

“What you can do on this website is help scientists look for things that are weird,” Morris said. People identify objects that don’t look right, then professional astronomers check them out. “Through this process they found a whole bunch of stars that misbehave.”

One of them was Boyajian’s.

“If we look at its colors, if we look at its spectrum, it behaves like all the other F-stars,” Morris said, “and so we were a little bit puzzled when we started looking at data.”

There were dips in light from Tabby’s Star, all right. There were smaller dips early in the mission that never really matched up. Then in March 2011 there was a huge dip of 15 percent of the star’s light, and it lasted for days, not hours as most transits do. Then in February 2013 there was an even bigger reduction in brightness of 20 percent. Nobody has come up with a plausible explanation for this.

“Whatever this is, this thing’s big,” Morris said.

No easy answer

An astounding array of possible explanations have been thrown out there. Examples include an object like Saturn with rings that could cause variations in the light curve, a passing comet, debris from a huge planetary impact like the one thought to have formed our Moon, and Tabby’s Star’s indigestion from having just swallowed a whole planet. The one in vogue at present is that a family of 10 to 20 comets, all giving off material, are creating these odd light curves. Morris doesn’t quite buy this one, either.

“The more bodies that you imagine being there, the easier it is to fit a light curve,” he said. “If you just keep adding new parameters into your model, eventually it will fit.”

“If you invoke wierdly shaped objects, you can fit it perfectly,” Morris added. “If you invoke the kinds of objects that we expect are most likely, it’s a lot harder. We really don’t know what this star is doing.”

Some have wondered if something between us and Tabby’s Star, maybe interstellar gas or dust, caused the strange light curves. Morris himself investigated this one. Back in May he got a Tweet—he said this is mostly how astronomers communicate these days!—noting that Tabby’s Star’s brightness was changing. He used the Apache Point Observatory to look for signs of absorption from interstellar gas or dust. But the spectra didn’t change even though the star was changing.

“We’re slowly ruling things out,” Morris said. “It’s not something in our solar system, it’s not something between us and the star; it’s got to be something near the star, but we don’t know what near the star could be doing this.”

As for wild speculation that the strange light curves could be caused by a Dyson Sphere or other “alien megastructure”:

“Extraordinary claims require extraordinary evidence, and I do not have any evidence to suggest that we can make a claim as extraordinary as that,” Morris said. He and a team of undergraduates at the University of Washington continue to work on the puzzle.

Coroner for the Stars

The second talk of CSI: Universe came from Prof. Melissa Graham of the UW, who does work on supernovae. These mark the death of a star, and Graham’s job is to figure out whodunnit.

Melissa Graham

Melissa Graham (Photo: Greg Scheiderer)

Graham pointed out that a star is considered alive if it’s in hydrostatic equilibrium; that is, when atomic fusion in the star’s core supports the star by counteracting gravity. Sometimes the death of a star is from natural causes. A typical star will fuse hydrogen and helium into carbon, then gradually fuses neon, oxygen, and heavier elements until eventually a core of iron forms. Graham said this means trouble, because fusing iron into something heavier is not exothermic; it doesn’t release energy.

“If you end up with a core of iron, your hydrostatic equilibrium suffers because you are losing out on that fusion in the core,” she said. “The core collapses because it can’t support itself anymore, the outer layers fall onto the inner layers, and you end up with a supernova explosion.”

Material blows away and leaves neutron star behind.

“That’s death by natural causes,” Graham said.

Type 1a supernovae are more interesting to stellar criminologists. These involve a white dwarf star, which is the remnant of a smaller star that doesn’t have enough mass to fuse carbon and oxygen into anything heavier.

“The carbon and oxygen core shrinks under its own self-gravity, and the outer layers are lost, which causes a really pretty planetary nebula,” Graham said. “The star is now supported by electron degeneracy pressure.”

This means the star isn’t alive because it’s not fusing elements.

“It’s more of a zombie star,” Graham said. “It’s died once and continues to live.”

The usual suspects

It’s a suspicious death when you see one of these explode. Graham rounded up the usual suspects: It could be a binary companion, such as a red giant or a sun-like star or another white dwarf. Sometimes it could be a pair of white dwarfs with a third companion star. A type 1a supernova also might from from a white dwarf’s impact with a primordial black hole or comet.

One way to figure this out is to simply look at the scene of the crime.

“Once this white dwarf star explodes, the other companion star would still be there,” Graham said. A companion would heat up and get brighter, so it might be detectable. Interstellar dust and gas may also light up from the energy of a supernova. Looking back at the scene later might detect such material that is at significant distance from the event. Graham is using the Hubble Space Telescope to check to find out if this is happening. She’s also looking forward to the completion of the Large Synoptic Survey Telescope, which is expected to find some ten million supernovae over its 10-year mission. With so many new examples we will, “really start to understand how these carbon-oxygen white dwarfs die,” Graham said.

More information:

Morris’s talk on YouTube

Ted Talk by Tabetha Boyajian

 

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Breaking barriers in the early ’60s space program

NASA played a key role in the integration of the workforce of the south during the early 1960s, and a recent book tells the tale of how that came about and of the African Americans who were key participants in that movement. We Could Not Fail: The First African-Americans in the Space Program (University of Texas Press, 2015) was written by Richard Paul and Steven Moss. Moss spoke about the story last week at the Museum of Flight.

It wasn’t altruism that drove NASA. After President John F. Kennedy made his man-to-the-Moon speech in May of 1962, the agency and its contractors suddenly needed about a quarter of a million engineers and rocket scientists to achieve that goal. They couldn’t afford to discriminate. In fact, Moss pointed out that Vice President Lyndon Johnson made a speech in Seattle in 1962 about NASA recruiting the best talent regardless of race. JFK knew getting the Civil Rights Act passed would not be a speedy process, but he made an executive order to address discrimination in federal employment. It was essentially the first mention of equal employment opportunity.

Policy doesn’t always make it to the streets immediately. Moss said that Houston Power and Light actually turned off the electricity to the Pelican Island Destroyer Base near Galveston, Texas because the utility didn’t approve of the nondiscrimination order. LBJ leaned on the local congressman, noting that if a naval base couldn’t be powered, Houston might not fare well in its efforts to land the Manned Spaceflight Center.

“The Navy got its power very quickly, and in September Houston got its space center,” Moss said.

NASA gets on board

Moss and Hawks

Author Steven Moss, left, and Harvey Hawks, a Museum of Flight docent, after Moss’s talk June 14 about the book We Could Not Fail. Hawks said during the Q&A period that, though he didn’t try to work for NASA, he faced similar challenges after graduating with an aeronautical engineering degree in 1963. (Photo: Greg Scheiderer)

At the start of this process in 1962 NASA was near the bottom of federal agencies in the hiring of African Americans. That began to change quickly, but again it took political pressure. In May of 1963 Attorney General Robert Kennedy discovered that, despite a large African American population in Birmingham, Alabama, only 15 African Americans held jobs with the federal government there. Kennedy leaned on Johnson, who leaned on NASA administrator James Webb, who leaned on Wernher von Braun, who was head of the Marshall Spaceflight Center in Huntsville, Alabama.

“Over the next six weeks NASA does more to engage in the hiring of African Americans than it has at any other time in its history,” Moss noted. In October of 1964—just before the presidential election—Webb threatened to move management personnel out of Huntsville over the Alabama’s discriminatory policies.

“Qualified people—blacks and whites—refused to work at Huntsville,” Moss said. “They refused to go to Alabama because of its laws, because of its violence—not just its reputation, but the very real violence against people.”

They also had trouble keeping people there.

“The turn-around at Marshall was pretty high compared to some other places, because people just did not want to be there once they saw it,” Moss said.

Von Braun became something of a “point man” on civil rights, according to Moss. He made a visit to Miles College, a historically black institution, in November of 1964 for the opening of a new science building.

“Von Braun goes there and it is a very bold statement,” Moss said, “that (NASA) is going to stand up for civil rights and for the African American community.”

The other great stand happened at Marshall. Governor George Wallace was gearing up for a presidential run, and organized a tour of the facility in Huntsville, bringing 200 Alabama state legislators with him. Von Braun made sure to be there to speak against Wallace’s segregationist policies.

“He tells them that Alabama’s hope for industrial growth is jeopardized by its racial policies,” Moss said, “and he tells them that attracting and keeping the best people would succeed if Alabama offers the same opportunities as other states.”

“The only federal official that could stand toe to toe with George Wallace was Wernher von Braun,” Moss said.

Moss noted that von Braun likely didn’t do this out of the goodness of his heart. Through co-author Paul’s conversations with Mike Neufeld, a historian at the Smithsonian Air and Space Museum and specialist on von Braun, and their own research, they concluded that von Braun was completely driven by launching rockets, and would do what it took to keep that going.

The pioneers

Officialdom was slow to conquer Jim Crow and the Klan, which were still strong forces in the south. Much of the book is devoted to profiles of some of the African American pioneers who helped make it happen despite the barriers. Moss highlighted several of them during his talk.

Montgomery

Julius Montgomery (Photo: FIT)

Julius Montgomery was the first African American hired as a professional at Cape Canaveral. He was the first African American to sign up for classes at the Florida Institute of Technology, which at the time was known as Brevard Engineering College. He played a key role in integrating the college. Today FIT offers the Julius Montgomery Pioneer Award to African American students who make outstanding contributions to the community.

Clyde Foster promoted compliance with equal employment opportunity at NASA. He helped Alabama A&M in Huntsville start a computer science program. A great many of the African Americans who worked at NASA began their careers at A&M. Foster also convinced NASA to do advanced training in management there—before this it was nearly impossible for African Americans to get such training and advance their careers, because the sessions were held at segregated institutions or hotels.

Crossley

Frank Crossley. (Photo: We Could Not Fail on Facebook)

Frank Crossley was one of the first black Navy officers, and was the first African American to earn a Ph.D. in metallurgical engineering.

“Although he was never a NASA employee, the work he did with metals and with alloys is significant for NASA’s success,” Moss said.

Charlie Smoot was hired by NASA as a recruiter. As an African American he could visit colleges and bring real information to prospective students about what it was like to be black and work for NASA. He organized presidents of black colleges and universities to help build a pipeline of qualified students.

George Carruthers is an astronomer who built the first observatory ever deployed on another celestial body, a UV telescope used on the Moon during the Apollo 16 mission.

Morgan Watson was one of NASAs first black engineers. Moss played a sound clip of an interview in which Watson gave what turned out to be the title of the book.

“We felt that the image of black people was riding on us as professionals,” Watson said. “We could not fail; we had go forward and do our best.”

“The pressure to succeed and the fear of failing was understood,” Moss noted.

In another clip Watson said that the space program changed the south by integrating African Americans into the workplace.

“By showing that there were black professionals that could do that,” he said, “it helped to break the walls down; it helped change people’s perception of black people in the south.”

As with the recent book Hidden Figures, Moss noted that the stories of the people he and Paul profile are not well known. In fact, they ran across cases in which the people’s own children or grandchildren had no idea of their accomplishments. Moss also said that, sadly, many of the African American NASA employees of the era are aging and in poor health, and were unable to participate in interviews.

We Could Not Fail promises to be a good read for the space history, but even more so for the stories of the courageous people who made that history.


You can purchase We Could Not Fail through the link above or by clicking the book cover image. Purchases through links on Seattle Astronomy help support our efforts to bring you great space and astronomy stories. We thank you!

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Plan your space vacation today!

There’s a place in our solar system where you could be like Superman! You could leap over the tallest building in the world in a single bound if it were built on the Martian moon Phobos. Burj Khalifa in Dubai rises to 2,722 feet, and you could clear it in one hop because gravity is not very strong on Phobos. This and other fascinating facts about the solar system are revealed in the new book Vacation Guide to the Solar System: Science for the Savvy Space Traveler (Penguin Books, 2017). Authors Olivia Koski and Jana Grcevich spoke recently at Town Hall Seattle.

Koski and Grcevich

Olivia Koski (left) and Jana Grcevich with their book Vacation Guide to the Solar System and their snazzy, official Intergalactic Travel Agent hats. (Photo: Greg Scheiderer)

The book sprung out of the work of an organization called Guerilla Science, which connects the public with science in unique ways. Koski, who is head of US operations for Guerilla Science, describes it as “an organization that believes that science is a tool of empowerment that belongs to everyone.” It was founded by graduate students in England, and Koski helped bring it to the US.

One of Guerilla Science’s projects is an Intergalactic Travel Bureau, which Koski calls a “pop-up agency where anybody can come and plan their vacation.” Five years ago she recruited Grcevich to be one of the bureau’s agents.

“I was procrastinating in writing my Ph.D. thesis,” she joked.

They’ve planned zillions of space vacations at live events and pop-up bureaus. The problem was that when people visited, they could typically squeeze in discussion about only a couple of possible destinations in any one sitting.

“We wanted to give them something that they could take away,” Koski said. “That’s how the book came about; we wanted to give them something that gave them the whole suite of options.”

Space vacations and reality

The authors say space vacations are not feasible just yet, but argue the concept isn’t so far-fetched.

“Assuming we don’t destroy ourselves first, humans will go to the places we describe in this book someday, almost without question,” Grcevich said. “With the right resources, and most important the will, we can travel to distant worlds.”

Thus from Vacation Guide to the Solar System Grcevich and Koski offered a bucket list of their top ten places to visit and things to do in the solar system:

  • Moon hop Jupiter (It has 67 of them)
  • Jump over the world’s tallest building on Phobos
  • Sleep in microgravity
  • Marvel at the geysers of Enceladus
  • Float in the skies of Venus
  • Meditate over Saturn’s hexagon
  • See a Martian sunset (They’re blue!)
  • Skydive into Jupiter
  • Ski the pink mountains of Pluto
  • Fly on Titan

The last would be Grcevich’s top choice.

“If I could go anywhere on vacation, I would go to Titan,” she said. The moon of Saturn has a thick atmosphere and low gravity, so people could fly under their own power using winged suits. Titan also has methane lakes and sand dunes, so it would be like a beach vacation (except it’s 300° below zero Fahrenheit.) “It would be fascinating to visit,” Grcevich added.

There were a great many kids at the talk, at least one of them a skeptic, a little girl who in the Q&A section asked, “Can you actually do any of those things?”

Koski said they get that question a lot. While it can’t happen right now, she noted that, a century ago, folks thought a trip to Mars would take 46 years. Now it’s six months.

“It’s pretty incredible to think about how much technology has changed in 100 years,” she said. Who knows what’s next?

“We’re very hopeful that we’ll be able to go on vacation to Neptune soon,” Koski added.

Go to the Moon today!

Since we can’t go now, they’ve created the next best thing: the Intergalactic Travel Bureau has built a free virtual reality app so you can enjoy a space vacation anyway.

“This is an app that turns your smart phone into a rocket ship,” Koski said. It features a virtual trip to the Moon, and vacations to Mars and Europa are in the works.

“We believe that space vacations are something that should be accessible to everyone, not just the people who can afford the ticket price that Elon Musk is charging to go to the Moon,” Koski added.

We recommend Vacation Guide to the Solar System enthusiastically. It’s a handsome volume with great illustrations by Steve Thomas, and it’s packed with interesting stuff about our solar system. The guide is a great way for kids and adults to learn the latest about what’s out there.


You can purchase Vacation Guide to the Solar System through the link above or by clicking the book cover image. Purchases through links on Seattle Astronomy help support our efforts to bring you great space and astronomy stories. We thank you!

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A lighthearted look at the dark universe

Two astronomers recently came independently to the conclusion that the way to figure out the fate of the universe is to build bigger and better telescopes. Prof. Sarah Tuttle of the University of Washington and Dr. Ethan Siegel of the Starts With a Bang blog and podcast both made informative and entertaining presentations about the dark universe at the most recent gathering of Astronomy on Tap Seattle at Peddler Brewing Company in Ballard.

Sarah Tuttle

UW astronomy Prof. Sarah Tuttle spoke at Astronomy on Tap Seattle May 24, 2017 at Peddler Brewing in Ballard. (Photo: Greg Scheiderer)

In her talk titled, “Dark Matter, Dark Energy, and Otters,” Tuttle joked that astronomers are “the universal accountants,” and that right now these bean counters are thinking that 68 percent of the universal energy budget consists of dark energy.

“If I were you, I would be concerned, because I both just told you that most of the universal energy budget is dark energy, and we don’t know what it is,” Tuttle said. “Dark matter we can measure and observe, but we don’t know what that is, either.”

There are a lot of theorized particles that could be in the dark-matter mix, but Tuttle said we don’t really understand them yet.

“We are in the process of measuring them and trying to figure out what it could actually be that is dark matter, how it is interacting with everything around it, because it is the dominant form of matter in our universe,” she said. We’re even more in the dark about dark energy.

“We are able to pin down that dark energy exists, that the universe is expanding and accelerating, and we’re not yet quite sure how to explain that,” Tuttle said.

How do we know?

Three experiments have helped reveal dark energy. Observations of the cosmic microwave background and type 1a supernovae have shown us that the universe is expanding. Tuttle is involved with a project called HETDEX—the Hobby Eberly Telescope Dark Energy Experiment—using a 10-meter telescope in West Texas. HETDEX is taking spectra of faint, young galaxies that are Lyman-alpha emitters to try to detect baryon acoustic oscillations. Huh?

“We’re using the clustering of a particular kind of galaxy to measure the distortion of spacetime,” Tuttle explained. She said it’s like throwing a grid of lights over a three-dimensional object—the lights will reveal the shape of the object.

“We use these galaxies to show us the shape of spacetime underneath to expose how dark energy changes with time,” Tuttle said. Other efforts like EBOSS and the South Pole Telescope are working on the same problem.

“We use a lot of different techniques to try to figure out what we’re doing to expose what dark energy is,” Tuttle said. “It turns out it’s going to take more beer and more time before we can answer that question.”

Our fate is in dark energy’s hands

Ethan Siegel

Dr. Ethan Siegel of the Starts with a Bang blog and podcast spoke at Astronomy on Tap Seattle May 24. (Photo: Greg Scheiderer)

Siegel’s talk was titled “The Fate of the Universe: After 13.8 billion years, where is everything headed?” He noted that it astronomers once saw three possible scenarios for the future of our universe. It could keep on expanding forever, it could eventually collapse back onto itself, or expansion and gravity could balance out just right for a universe that remains about the way it is.

“That’s what we thought for years and years and decades and decades: the fate of the universe is going to be one of these three,” Siegel said. “The whole field of cosmology, which is my field, was the quest to measure what’s it going to be.”

“They’re all wrong,” he said. Dark energy is the wild card. Siegel pointed out that matter dilutes with the expansion of the universe, and radiation gets weaker; it redshifts. Dark energy? We’re not so sure.

“If there’s any type of energy that’s inherent to the fabric of space, then as space grows this energy is just growing,” Siegel explained. “As your universe grows, it’s like you’re just making more and more of this new type of energy if there’s any non-zero energy to space itself.”

A big assumption

Siegel gave a lengthy description of the fate of the universe, from the boiling oceans of Earth to the last black hole standing. It was all based on the assumption that dark energy is constant. But what if it gets stronger over time? Siegel said that would mean that galaxies and solar systems and the Earth would all get torn apart.

“In the fiery final moments, everything, even the atoms that made you up, even the nuclei that made you up, would be ripped apart as well,” he said. “That fate is known as the Big Rip, and it’s possible. I don’t think it’s right, but you can’t be sure unless you measure it.”

Dark energy could get weaker, too, and that could lead to the opposite outcome, a big crunch.

“That’s something we could also measure,” Siegel said. “We haven’t constrained it well enough to know that it won’t rip or that it won’t turn around and crunch again. The way we’re going to find out is through bigger and better telescopes and observatories.”

HETDEX is a big part of that, Siegel noted, and said that the ESA’s Euclid telescope will measure dark energy to better precision than ever before. NASA’s WFIRST (Wide Field Infrared Survey Telescope), scheduled to launch in mid-2020, and the Large Synoptic Survey Telescope, under construction in Chile with hopes of being fully operational by 2022, will also make key contributions to this work.

“If you think that this stuff is fun, I’m telling you it’s going to get even better in the 2020s,” Siegel concluded. Stay tuned.


If you couldn’t attend AOT Seattle, you can watch online! In May they live-streamed the event for the first time.

More reading:

  • Article about BOSS from a 2016 Astronomy on Tap
  • Article about the LSST from a 2016 Astronomy on Tap
  • Siegel’s talk about the expanding universe given to Rose City Astronomers in February
  • Siegel’s talk about the discovery of gravitational waves given to RCA in 2015
  • Siegel’s book, Beyond the Galaxy
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Seeking life beyond Earth

The 21st Century is an exciting time for those who study exoplanets. As the number of confirmed worlds in orbit around far-away stars grows almost daily—as of this writing the NASA Exoplanet Archive lists 3,489 of them—Lucianne Walkowicz says it’s becoming more than just a tally.

Lucianne Walkowicz

Adler Planetarium astronomer Lucianne Walkowicz gave a talk titled “Seeking Life Beyond Earth” May 23, 2017 at the Pacific Science Center. (Photo: Greg Scheiderer)

“We are starting to get to know these planets not just as a new marble in the bin, but something that you can understand what its environment might be like,” Walkowicz said. “We’re right around the corner from being able to really understand these places as worlds, and not just compare their size or their orbit to the planets in our solar system.”

Walkowicz is an astronomer at the Adler Planetarium in Chicago who earned her master’s and doctoral degrees at the University of Washington. She was back in Seattle recently to give a talk at the Pacific Science Center about the latest in exoplanet research and the prospects for figuring out if life exists on any of them. The talk complemented the Mission: Find Life! astrobiology exhibit that is presently running in the center’s Portal to Current Research space. (Check our previous post and podcast for more about the exhibit.)

While a majority of the early exoplanet finds by the Kepler mission were of gas giants on the order of Jupiter, Walkowicz said that was because bigger planets are easier to find because they block more light when they pass in front of, or transit, their host stars.

“The smaller planets that are more like Earth that might be out taking a full year to go around their star are even harder (to find) because you have a very small signal that takes years and years to repeat,” she said. As time went on, more and more smaller exoplanets were detected.

It turns out that, “The things that are a little bit bigger than Earth and little bit smaller than Neptune are super common,” Walkowicz noted. This threw planetary formation theorists for a loop. They’d spent careers constructing formation models that did not result in planets of that size because we don’t have any in our solar system. While journalists tend to rush toward a declaration of some of these planets as “Earth-like,” Walkowicz said that’s typically premature.

“It’s not the discovery of life around other stars,” she said of the finding exoplanets in this size range, “but it does mean that there is a lot of real estate for us to look.”

Goldilocks lives in the habitable zone

Walkowicz discussed the concept of the so-called habitable zone around stars—an area that could be at the right temperature for liquid water to exist on a planet’s surface. This is a ballpark figure; she noted that distant astronomers looking at our solar system would declare Venus, Earth, and Mars all to be within our Sun’s habitable zone. Yet these are very different worlds and two of them are not particularly hospitable at present. The type and kind of starlight, a planet’s orbit, tidal heating, radiation protection, and the actual existence of water, ice, haze, or clouds all can make big differences for a planet’s potential habitability.

As we move forward, astronomers will look not just at exoplanets’ location, but also at their biosignatures, which Walkowicz explained are the, “signatures of the chemical species that make up a planet’s atmosphere and whether they mean that life can be there.” Finding oxygen, ozone, water, carbon dioxide, and methane all could be positive indicators for life. On the other hand, finding carbon monoxide in a planet’s atmosphere would mean life is less likely. But even the right ingredients don’t necessarily mean life exists.

Local help from VPL

VPL logoThe Virtual Planetary Laboratory (VPL) at the University of Washington is leading the way in looking at such biosignatures and interpreting what they could mean for varying planets around different types of stars. Having so many possible combinations can be on the confusing side.

“Planets are complicated,” Walkowicz said. “They’re not just spheres orbiting around a star that’s getting some illumination at some distance.”

“It’s usually just not one thing, its the balance of things overall. You have to be able to look at the complete picture in order to interpret what you find,” she added.

That is difficult to do at present, but a couple of future space telescopes will be able to help. The Transiting Exoplanet Survey Satellite (TESS) is scheduled to launch next March, and the James Webb Space Telescope is targeted for launch in October 2018. TESS will look for more exoplanets by watching for their transits in front of some 200,000 nearby stars. The Webb, according to Walkowicz, will look into the infrared and explore the plentiful small, red stars in the galaxy and try to take the spectra of the atmospheres of planets in orbit around them.

“In some cases, we’ll be able to get this chemical fingerprint of what the planet’s atmosphere is made up of,” Walkowicz enthused. She added that the VPL’s work will help astronomers decide which planets to study with the new space telescopes—it will be important to winnow the field down to the most promising candidates, as competing demands for time on these scopes will limit the observing opportunities for any one project.

We might well have a better idea if there’s life elsewhere in the not-too-distant future.


 

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Herschel’s observation of comets

To say that Woody Sullivan is interested in William Herschel would be quite an understatement.

“I have dressed up as Herschel for Astronomy 101 half a dozen times,” said Sullivan, a professor emeritus of astronomy at the University of Washington. He started a file on Herschel, the 18th and 19th Century astronomer, some 30 years ago, but can’t exactly pin down why he was so drawn to him.

“I have eclectic interests,” Sullivan said. “I’m always looking for what I call astronomy on the edges: astronomy and music, astronomy and astrology, history, literature, sundials.”

“Herschel was that way to some degree,” Sullivan added. “Perhaps that was it; I saw a fellow traveler there.”

Woody Sullivan

Prof. Woody Sullivan at the May meeting of the Seattle Astronomical Society. (Photo: Greg Scheiderer)

Sullivan noted that it was nine years ago that he started doing more serious research into Herschel with the intent to write a biography. While there have been many penned, including a couple in the last decade or so, Sullivan noted that none have been particularly scholarly, and so that’s a void he’s aiming to fill. After all of that research, the actual writing has begun.

“I do need to get on because I’m getting on,” Sullivan quipped. He spoke about his work at the most recent meeting of the Seattle Astronomical Society, discussing Herschel’s work on comets, about which few biographers have gone into much detail.

While his sister Caroline Herschel discovered eight comets, six of which bear her name, William never found one, though he came close a couple of times. He once reported a comet discovery, but the French astronomer Jean-Louis Pons had already found it a month before. Then in 1781 Herschel reported another comet discovery. But after six or eight months of observation, astronomers more skilled in the calculation of orbits found this new object to be in a nearly circular one well beyond Saturn’s. It was a new planet: Uranus.

First to “discover” a planet

“It’s hard to think about what a new planet means. What planets did we have before? We had the same planets that we had had since Ogg the caveman,” Sullivan noted. “Herschel was the first one to find a planet telescopically, and this made him instantly famous.”

William Herschel

William Herschel. (Photo: Public domain)

Herschel parlayed that into a gig as the court astronomer for King George III. It was actually a pay cut from Herschel’s work as a professional musician in Bath, but he supplemented his income by building and selling telescopes, and by marrying a rich widow. Herschel was mostly interested in deep-sky objects, but comets came to his attention on occasion, in part because he was interested in change.

“A comet is change par excellence,” Sullivan said. “It just appears in the sky, it’s different every day, you never know what’s going to happen.”

While Caroline wanted to discover them, William aimed to understand what they were. Sullivan noted that this wasn’t what most astronomers were doing then.

A different sort of astronomer

“Astronomy at that time was measuring accurate positions of things; planets and their moons and comets and stars for catalogs,” he said. “That’s why you had the Greenwich Observatory. The government was paying for that, not because they loved astronomy but they loved the navy, and you needed that for navigation.”

Herschel’s observations of the great comets of 1807 and 1811 were interesting. Sullivan pointed out that astronomers at the time thought there might be a planet or other object at the nucleus of a comet. Herschel was the first to claim he’d spotted one. When others couldn’t find it, Herschel chalked it up to the superior optics of his telescope. By the 1811 comet, he was trying to figure out if the nucleus reflected light from the Sun, or generated its own light. Herschel declared that the nucleus of this comet was perfectly round, and thus self-illuminated, because if it reflected light it would show phases. Sullivan, after poring through Herschel’s logs, concluded that he had fallen into a trap that scientists need to avoid.

“There’s just no doubt that he was picking and choosing the observations that fit into his concept,” Sullivan said. It was a bit of a reach to claim to be able to determine the roundness of an object of perhaps an arcsecond in width within the fuzzy coma of a comet.

“He’s getting all of his theory and observations mixed up,” Sullivan said. “This can get you in trouble.”

Though Herschel missed on this particular analysis, Sullivan noted that Herschel made some interesting conclusions, particularly in describing the tail of a comet as its atmosphere being pushed away by pressure from the Sun. Though it’s not the atmosphere, but dust and gasses, nobody to that point had really postulated that the Sun might be pushing on things. Other descriptions Herschel made of the mechanics of comets are not so far off from what is held true today.

Sullivan’s presentations are always interesting, and we look forward to the completion of the book and to learning about William Herschel, a fascinating character in the history of science.


 

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Mars “big thinkers” envision people on the Red Planet

After hearing about the pros, cons, and challenges of sending people to Mars, most of the audience who attended “National Geographic: Mankind to Mars” at Benaroya Hall Monday evening decided that such an effort would be worthwhile. A significantly smaller percentage of attendees would be willing to make the trip themselves.

The straw poll by applause came after a panel discussion moderated by Andrew Fazekas, also known as The Night Sky Guy, a space journalist who writes a column for National Geographic and who is the author of Star Trek; The Official Guide to Our Universe: The True Science Behind the Starship Voyages (National Geographic, 2016). The other panelists were Jedidah Isler, an astrophysicist from Vanderbilt University, and Ray Arvidson, a planetary scientist at Washington University in St. Louis who has had a hand in Mars missions going back to Viking in the 1970s and is the deputy principal investigator for the Mars rover Opportunity mission.

Why Mars?

Fazekas said he got interested in space when he was a little kid and his father showed him Mars through a telescope.

“Mars has always been particularly fascinating to humankind because it’s our nearest neighbor,” Fazekas said, “a neighboring world that beckons us.”

Panel at Mankind to Mars

(L-R) Andrew Fazekas, Jedidah Isler, and Ray Arvidson discuss “Mankind to Mars” May 15, 2017 at Benaroya Hall in Seattle. Photo: Greg Scheiderer.

The presentation made liberal use of video clips and images from the Mars miniseries aired by the National Geographic Channel last fall. The panelists covered a wide range of topics, including the history of Mars, its past possible habitability, research by rovers and orbiters at Mars and by people on Earth, rocket and spacecraft design, private space ventures, and the possible setup for a human outpost on Mars.

They also discussed a litany of challenges to making a successful human mission to Mars happen, including getting there and landing safely, radiation, dust, fuel and power, agriculture on Mars, and a host of threats to human physical, mental, and emotional health.

Isler said she’s interested in the “socio-technological” aspects of a human mission to Mars, and thinks interest is building because we keep learning.

“It seems like a good amount of information is there, we’ve got a lot of poepole interested in it,” she noted. “I think it’s just a good time because we’ve got all the right pieces, or many of them.”

There’s also important science to be done, Arvidson said.

“What we’re looking at on Mars is the record in the rocks that’s long lost on Earth,” he said. “It’s the first billion years of geologic time. Earth is very active; Mars was active early but then kind of slowed down, so the rock record is still preserved. That’s the period of time when life got started and evolved on Earth. It may have also gotten started and evolved on Mars.”

Where to land

Scientists are debating right now about possible human landing sites on Mars, and dozens of them have been proposed by people with varying scientific interests. Arvidson said it will take many years to whittle those down and make a choice. The target spot will have to be one that is safe to land on, away from the poles and at low elevation so it is not too cold, and will need to offer a balance between science, safety, and sustainability.

“Wherever we go, there are lots of questions about early Mars and habitability and life,” Arvidson said. “I think the first human expedition site will be a science station, most likely, for detailed exploration between humans and robotic systems.”

Isler said that machines will do a lot of work, but that people are essential for the ultimate success of a Mars mission.

“Robots are beneficial, but they are limited,” she said. “You will always want, I argue, the dynamism, the spontaneity of human beings.”

When shall we start packing?

“Depending on what we want to do, nationallly and internationally, where the finances are, and what the reasons are and the justification, we can do this in the next few decades,” Arvidson said, speculating that we’ll arrive on Mars in the 2040s. Isler thinks it will take longer than that to figure out the human factors involved.

“The rumor on the street is that we’re always 20 years from Mars,” she quipped.

The panel speculated about an “Armstrong moment” on the day that a person from Earth sets foot on Mars for the first time. Isler said it will be a “moment where people will be be super connected with the fact that we as a species have now moved ourselves to this place successfully.”

But she added that we need to be careful how we talk about the endeavor, as huge numbers of people have been thinking about and working on getting humans to Mars for years.

“We have to do a better job this time around of implying and also asserting that it wasn’t just one person, this was not rugged individualism,” Isler said. “This is a team effort.”

She also thinks it will go a bit differently than Neil Armstrong’s line after stepping onto the Moon.

“When the first Mars explorer steps off she might Snapchat,” she laughed.

Fazekas seemed most optimistic about the timeline.

“If we put all of these components together—the technology, the science, the engineering, the willpower, understanding the challenges—we may one day all have a chance to become a tourist on Mars,” Fazekas said.

Further reading and viewing:

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