Category Archives: astrobiology

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.



AstronoMay and more at PacSci

It’s been a month filled with astronomy at Pacific Science Center, and they’ll wrap it up big this weekend with their celebration of AstronoMay Saturday, Sunday, and Monday. According to Dave Cuomo, supervisor for science interpretation programs and the Willard Smith Planetarium at the center, there will be a lot going on.

“We will have expanded planetarium shows,” Cuomo said. “We will have lectures about astronomy featured on our Science on a Sphere exhibit. We will talk about astrobiology in some of those. We will have space scientists that visitors can speak with and talk about their study and research about astronomy. And, weather permitting, we will have some solar telescopes out so you can safely observe the Sun.”


Willard Smith PlanetariumThere’s a great variety of selections for shows in the planetarium. One that will run this weekend is called “The Search for Life.”

“It will be an exploration of the different ways that astrobiologists are looking for life, both in the solar system and outside of the solar system,” Cuomo said. That show is a great complement to the “Mission: Find Life!” exhibit about astrobiology that is presently in the center’s Portal to Current Research space. (See our post from last month for more about that.) Another show, titled “Let’s Explore Light,” is about the basic physics of light.

A third planetarium show called “The Skies of Ancient China,” created to complement the popular Terracotta Warriors exhibit at the center, looks at more than 4,000 years of Chinese astronomy. Cuomo noted that Chinese astronomers in the day had a pretty high-stakes job.

“They were hired by the emperor because the emperor ruled the Earth because he had the mandate from the heavens,” Cuomo explained, “so he needed to be able to know what was going to happen in the sky.”

The astronomers predicted planetary conjunctions and eclipses of the Sun and the Moon. Conjunctions in particular were considered omens of pending regime change, and, say what you will about whether the heavens influence lives on Earth, a couple of empires actually did flip at around the time of a conjunction. More amazing is the accuracy of both the Chinese astronomical observations and their record keeping.

“Modern astronomers have associated at least nine supernova remnants with ‘guest stars’ that the Chinese observed and recorded the location of,” Cuomo marveled. “There is also almost two thousand years of history of a returning star every 76 years, which we now know was Halley’s Comet.”

Cuomo found it interesting that there wasn’t much mythology around the heavens with the Chinese astronomers as compared to that in many other cultures. He and three of the center’s planetarians created the show with research help from the British Library, the Hong Kong Space Museum, and many others across the country and the world.

The daily schedule for planetarium shows is on the PacSci website and also on our Seattle Astronomy calendar page. We saw “The Skies of Ancient China” last week and found it to be exceptionally well done.

Solar eclipse

The astronomy doesn’t stop once May ends. The Pacific Science Center is gearing up for the total solar eclipse that will happen on August 21. The entire month of August will be PacSci “Up in the Sky.”

“We will talk about solar astronomy, observational astronomy, weather; anything that you look up to see, we’ll want to talk about,” Cuomo said. They’ll also have eclipse glasses on hand for safe viewing of the Sun, and probably some solar projectors for watching the eclipse.

Although the eclipse will only be partial in Seattle, the center plans to open early, at 8:30, that morning.

“We will have solar telescopes available and educators talking about the eclipse and the science of the eclipse,” Cuomo said. First contact—when the Moon starts moving across the face of the Sun—will happen at 9:08 a.m. at PacSci, and it will be over by 11:30. But they’ll have live feeds from other eclipse events from all across the country so you can keep watching.

Cuomo will be in Madras, Oregon for the total eclipse, along with other educators from the Pacific Science Center in partnership with Lowell Observatory. They’re leading a four-day trip to view the total eclipse. Space is limited; if you’re interested in going along, you can find out more online.

Podcast of our interview with Dave Cuomo


Busy week ahead on the astro calendar

There’s something for everyone on this week’s astro calendar, with a new scale model solar system opening, two great lectures, a theater/science mashup, and a variety of club events on the docket.

A new scale model of the solar system that you can explore through geocaching opens today, May 1, on Bainbridge Island. Check out our article or podcast from last week to learn more.

Proxima b

You’ve probably heard by now of the discovery of a planet orbiting our nearest stellar neighbor, Proxima Centauri. (If not, check out our article featuring UW professor Rory Barnes discussing the possibility of the habitability of Proxima b.) The UW Astrobiology Program and the NASA Astrobiology Institute will host a panel discussion about the planet at 7 p.m. Wednesday, May 3 in room 120 of Kane Hall on the university’s campus in Seattle.

The panelists include Guillem Anglada-Escude, lead discoverer of the planet and University of London lecturer; Victoria Meadows, University of Washington astrobiology professor and primary investigator for the Virtual Planetary Laboratory; Barnes; and Olivier Guyon, University of Arizona professor and project scientist for the Subaru Telescope.

It’s free but registration is required; as of this writing there were still some tickets available.

Searching for Martians

Bob Abel talkMars may have been habitable before Earth was, and might be still. So where are the Martians? Olympic College professor Bob Abel will give a talk about the history of Mars and the prospects for past, present, and future life there at 6 p.m. Thursday, May 4 in room 117 of the Engineering Building on the Olympic College campus in Bremerton. It’s free.

Abel gave a talk on the same topic last week at Astronomy on Tap Seattle. Our recap of that event is coming soon.

Astronomy Day at MOF

The Museum of Flight celebrates Space Day during its Free First Thursday at 5 p.m. May 4. Local astronomy clubs will be on hand with information about their activities and they’ll have telescopes for observing if the weather cooperates. A special presentation at 6 p.m. will take a look at the technical challenges of getting Apollo to the Moon, and what that means for present-day space efforts. Tony Gondola, a solar system ambassador and coordinator of the museum’s Challenger Learning Center will be the speaker.

The event runs through 9 p.m.

Mashing up science and theater

Centrifuge2Infinity Box Theatre Project will present Centrifuge 2 at 8 p.m. this Friday and Saturday, May 5 and 6, at Stage One Theater on the North Seattle College campus. Centrifuge pairs science writers and playwrights to craft brand-new one-act plays featuring current science. Seattle Astronomy’s Greg Scheiderer participated in the event last year and will be one of the science writers again this time around. Check out our article and podcast from last year to learn more about Centrifuge and Infinity Box.

Open house at TJO

The Theodor Jacobsen Observatory at the University of Washington will hold one of its bimonthly open houses at 9 p.m. Wednesday, May 3. The topic for the evening’s talk had not been published as of this writing. Volunteers from the Seattle Astronomical Society will be on hand to offer tours of the observatory and, weather allowing, a look through its vintage telescope.

Club events

The Tacoma Astronomical Society will hold its monthly meeting at 7:30 p.m. Tuesday, May 2 in room 175 of Thompson Hall on the University of Puget Sound campus in Tacoma. The topic will be club participation in viewing the August 21, 2017 total solar eclipse.

The club will also offer one of its free public nights at 9 p.m. Saturday, May 6 at the Fort Steilacoom campus of Pierce College. The indoor session will be a presentation about constellations. They’ll break out the telescopes for observing if the sky is clear.

The Spokane Astronomical Society plans its monthly meeting for 7:30 p.m. Friday, May 5 at the planetarium at Spokane Falls Community College. Club member Nick Monkman will talk about the ABCs of finding objects in the night sky.

The Seattle Astronomical Society plans its monthly free public star parties for 9 p.m. Saturday, May 6 at two locations: Green Lake in Seattle and Paramount Park in Shoreline. Bad weather causes cancellations, so watch the website for updates.

You can always scout out future events on our calendar page.


The search for ET at Pacific Science Center

They’re thinking a lot about extraterrestrial life these days over at the Pacific Science Center, where two new exhibits explore how scientists are working to identify far-away planets that may harbor life, and how we’re going to feed ourselves while we’re on our way to pay a visit.

Mission: Find Life!The exhibit Mission: Find Life! opened up last month in the science center’s Portal to Current Research space. Erika Harnett, a University of Washington professor of Earth and Space Sciences who serves as the education and outreach lead for the UW’s Virtual Planetary Laboratory (VPL), was one of the key players in developing the content for the exhibit.

“We really wanted to connect the research being done by the Virtual Planetary Laboratory and some of the more cutting-edge science,” Harnett said.

It’s all in the biosignature

They decided to focus on examining the biosignatures of exoplanets. Harnett noted that we actually have the technology to take images of planets orbiting other stars, even though the images only amount to a pixel or two.

“From that single pixel you can actually glean quite a bit of information,” Harnett noted. “Scientists are trying to figure out if, from that, you can actually start to see if there are signatures of life on a planet, and really the initial work that they’re doing now is defining what are the signatures of life on Earth.”

The color of the light might tell you if you’re looking at ocean or continents. You might even identify the chemical components of a planet’s atmosphere or the types of molecules that are there.

Promotional material for the exhibit notes that, for finding life, “the color purple may be the key.” Harnett explained that that’s because red dwarf stars are plentiful in the universe, and they last a long time—long enough to give life plenty of time to develop. Whatever life appears would be faced with much redder light than we have here on Earth.

“Life will want to make use of it as much as possible, so it’s going to be either purple or black vegetation, instead of green, to be able to absorb as much electromagnetic radiation in the visible as possible,” Harnett said. She noted that, for the exhibit, they wanted to convey the speed of discovery—scientists verify new exoplanet discoveries practically every day. She also wanted to set expectations about what sorts of life might be found. Spoiler alert: it won’t likely be little green men like the ones on the socks Harnett wore when we spoke.

“It’s more likely that it’s going to be something like microbes or bacteria, because that’s actually what most of the life on Earth is. It’s not the most visible, but it’s the most plentiful,” she said.

Watch an exoplanet transit

One of the cool, hands-on features of the exhibit gives visitors a look at how scientists using the Kepler Space Telescope actually find exoplanets. A lighted globe represents a star, and you can spin a couple of planets around it.

“Then they have a sensor off to the side,” Harnett said—it’s actually inside a model of Kepler. “On a screen you can see the light from the star, and then as the planet transits you can see the dip” in the amount of light that arrives at the sensor.

“You get to actually play with that and explore what the change in signal associated with a planetary transit looks like,” she added.

Another interactive feature of the exhibit is a large touch screen that uses the NASA Eyes on Exoplanets program to let visitors explore planets.

Communicating science

The Mission: Find Life! exhibit is part of the VPL’s work funded by the NASA Astrobiology Institute, which requires that a portion of funds be reserved for education and public outreach. VPL has created several science-on-a-sphere shows and trained numerous graduate students to be science communication fellows.

“The Portal to Current Research project is the culminating part of our work,” Harnett said. She has been involved with the Pacific Science Center’s communication fellows program for about a decade and said she feels effective communication about science is important.

“If scientists do a better job of communicating their science there would not be quite as much mistrust of science,” she said. “Everybody needs to get out more into the community and be doing more communication and writing for the general public, as opposed to just writing the peer-reviewed articles that will go into a journal and ten people will see.”

Harnett said they’re working to line up astrobiologists to offer talks during the exhibit’s run, especially during Astrono-May at the science center. Mission: Find Life! runs through September 4, 2017 at the Pacific Science Center.

What’s for lunch?

Feeding Future AstronautsAnother new exhibit called Feeding Future Astronauts is just across the gallery from the Portal to Current Research space. Growing food in space will take a lot less energy than carrying a bunch of it along, and the exhibit highlights some of the things NASA is trying. In the test garden of the exhibit they’re growing “outredgeous” lettuce, “Tokyo bekana” cabbage, and “Red Robin” cherry tomatoes. The latter will be a challenge because tomatoes require pollination, and as far as we know there are no bees in space. ISS astronauts are experimenting with hand pollination and how it will work in microgravity. The Red Robin might be a good variety of tomato to try in your Seattle garden; the ones in the exhibit were doing great for early April with only artificial light.

Podcast of our interview with Erika Harnett: