Universe Update, March 2014
By Ryan Wyatt
The third Thursday of every month, the Morrison Planetarium hosts “Universe Update” at the 6:30 planetarium show during NightLife. I select my favorite astronomy stories from the past month, and I give a brief run-down of current discoveries while taking audiences on a guided tour of the Universe. As you may or may not know, the planetarium sports a three-dimensional atlas of the Universe, so we can take you places virtually while talking about the latest astronomy news.
I always start at Earth and work my way out to cosmological distances, so I’ll list the news stories in the same order—from closest to farthest from home.
Starting very close to home, my first story literally connects to Earth! Our magnetosphere, the region of space dominated by Earth’s magnetic field, envelops us and helps shield our planet from the solar wind, made up of charged particles streaming away from the Sun in all directions. We can’t see all the action taking place quite close to home, but the magnetosphere deflects those charged particles and prevents them from causing damage to our atmosphere, our power grids, and our very cells. And according to MIT scientists, it does an even better job than we realized! They have identified a plume of low-energy plasma streaming away from Earth that blunts the Sun’s effects. It reinforces the shielding effect and provides protection against solar storms. Good for us!
Buried inside Earth’s magnetosphere, energetic charged particles bounce around harmlessly (well, unless you’re an astronaut or a satellite) in the Van Allen Radiation Belt. (And you thought space was empty? Ha!) NASA just announced the discovery of “zebra stripes” in the inner belt: regions where Earth’s rotation interacts with the magnetic field to distort the charged particle distribution, “much like taffy is stretched and folded in a candy store machine,” according to Aleksandr Ukhorskiy of the Johns Hopkins Applied Physics Laboratory (APL) in Maryland.
In short, giant invisible space taffy structures help protect Earth from the Sun! Sort of.
Anyway, moving just a little farther from home, we encounter the Moon… NASA just announced the release of a crazy high-resolution mosaic of the lunar north polar region—covering an area equivalent to a quarter of the United States and constructed from 10,581 images (try that in Gimp), the map measures details down to about two meters (6.5 feet). Best of all, all the data are available online via the Lunar Reconnaissance Orbiter Camera (LROC) archive and, more spiffily, via an interface that allows you to pan and zoom. Have fun!
And while you’re having fun, you can help scientists explore our nearest neighbor. As citizen-science hub CosmosQuest put it in a recent press release, “With over 500 million craters on the moon alone, and new data coming in from NASA’s Lunar Reconnaissance Orbiter daily, there is quite a lot of science to be furthered.” Although I’m not such a fan of their use of the passive voice, I can’t argue with the results! CosmoQuest’s MoonMappers project just published a research article, representing contributions from literally thousands of volunteers poring over the Moon’s surface and characterizing the features observed in the imagery. If you’re interested in lending a hand, you can head directly to the MoonMappers site to begin exploring…
I love talking about asteroids, and this month, we had an interesting announcement from the Hubble Space Telescope describing the mysterious disintegration of Ateroid P/2013 R3. In a series of images, you can see the asteroid fragment into perhaps ten smaller pieces. The press release puts it nicely: “The Hubble data showed that the fragments are drifting away from each other at a leisurely 1.5 kilometres per hour—slower than the speed of a strolling human. The asteroid began coming apart early last year, but the latest images show that pieces continue to emerge.” Although comets do this kind of thing all the time (cf. Comet ISON), we haven’t seen an asteroid behave quite like this before, so it’s well worth watching!
I’m skipping over other news about goings-on in our solar system, since the biggest stories this month came much farther from home.
Indeed, the Kepler Mission made a big splash at the end of February by announcing whole new solar systems outside our own—a “planet bonanza,” the discovery of 715 new exoplanets orbiting 305 different stars! Although I feel compelled to admit that I detest the artwork that accompanied the press release, I truly admire the dogged science: “Since the discovery of the first planets outside our solar system roughly two decades ago, verification has been a laborious planet-by-planet process. Now, scientists have a statistical technique that can be applied to many planets at once when they are found in systems that harbor more than one planet around the same star.” The mention of “a statistical technique” may start to make your eyes glaze over with boredom (unless you like your stats with cats), but scientific discoveries often require the tenacity and persistence of number crunching.
Speaking of statistics, I’m often quick to note that many of the pithy headlines about exoplanets often rely on (occasionally tenuous) statistical arguments. For example, when the University of Hertfordshire announced, “Every red dwarf star has at least one planet.” They based that statement on counting up the number of planets they found around red dwarfs, then using Bayesian analysis to estimate the fraction of red dwarfs that should have planets, given the sensitivity of their survey. All well and good. But of course, on the face of it, that headline is almost certainly false, and they admit as much early on in the press release, “The study identifies that virtually all red dwarfs, which make up at least three quarters of the stars in the Universe, have planets orbiting them.” (Emphasis mine.) Um, yeah, at least in American English, “virtually all” doesn’t translate to “every,” but that doesn’t invalidate the exciting result. It just means we need more responsible composing of headlines.
The study also notes that many of the red dwarfs likely harbor so-called “Super-Earths,” exoplanets with a mass, say, five to ten times the mass of Earth. Since we only know the mass of these objects, we must engage in informed speculation about their other qualities. Some planetary scientists think Super-Earths could look a lot like Earth, but a new study suggests they could be “dead worlds,” in hospitable to life. Time will tell.
A lot of the uncertainty around Super-Earths and other exotic exoworlds arises because scientists are still sorting out the process of planet formation. We obviously see many planets orbiting other stars, and we also see disks of gas and dust surrounding young stars, inside of which we presume planets are taking shape. We then use computer models to simulate how this process might work. A recent announcement from NASA claims that magnetic fields could explain some of the excess infrared radiation observed coming from these nascent planetary systems. According to the press release, “the new models better describe how planet-forming material around stars is stirred up, making its way into future planets, asteroids, and comets.” Eventually, these simulations, in combination with more observations, may help reveal how our solar system and others took shape.
And of course, once you have an idea about how planets form, the next big question to ask is how life might get started. Everything we know about the early Earth suggests that it provided a challenging environment for life, and although some laboratory experiments have replicated the origin of life’s building blocks in such a hostile environment, the process by which those constituents assembled into living cells remains even more mysterious. This past month, NASA described a new study that takes an innovative approach toward the question, using fuel cells to test chemical reactions that could have led to life. “Something about Earth led to life, and we think one important factor was that the planet provides electrical energy at the seafloor,” said Laurie Barge of NASA’s Jet Propulsion Laboratory in Pasadena. “This energy could have kick-started life—and could have sustained life after it arose. Now, we have a way of testing different materials and environments that could have helped life arise not just on Earth, but possibly on Mars, Europa and other places in the Solar System.” The University of Leeds offers up a press release with a video describing the research, and for the deeply interested, you can find the actual research article here with a link to the PDF.
So far, all the places I’ve described reside within our Milky Way galaxy, the astronomical metropolis in which we reside, along with hundreds of billions of stars and planets and a smattering of gas, dust, and dark matter. Indeed, for the first time, we may have detected a distinct signal from dark matter at the center of our galaxy! But the Milky Way is only one of hundreds of billions of galaxies in the observable universe, so there’s a lot more territory to cover.
Indeed, we’re still mapping the region of space nearby, and a press release this month from York University describes the Milky Way amidst a “Council of Giants” that includes dozens of bright galaxies within about 35 million light years of Earth. Studying the distribution (and even alignment) of these giant galaxies could help us understand the environment in which our local intergalactic neighborhood took shape, billions of years ago.
And to highlight just one particular galaxy (also seen in the accompanying image above), the Hubble Space Telescope recently imaged the spiral galaxy ESO 137-001, revealing streamers of stars and gas being ripped away from the galaxy. The press release graphically refers to the spiral galaxy spilling its blood and guts as it moves through superheated gas in the center of the galaxy cluster Abell 3627. “This cluster is violently ripping the spiral’s entrails out into space, leaving bright blue streaks as telltale clues to this cosmic crime.” In space, no one can hear you scream…
And finally, at a distance far, far from home, we can reflect on the major announcement that astronomers had discovered evidence for cosmic inflation in the twisted light of the Cosmic Microwave Background. We posted a Science Today article about this the day of the announcement, so I’ll let that stand on its own, but let’s just say it’s a big deal! If it turns out to be true…
Ending on a human note, however, it’s important to note that real people devise these theories, and a major announcement that confirms their idea can come as a welcome and astonishingly rewarding surprise. In addition to the charming video of Stanford cosmologist Andre Linde learning the news, I also liked the press release from the University of Michigan that describes physicist Katherine Freese’s reaction. She noted that, “There are only a small number of simple models that can still accurately describe the observations,” and one she proposed back in 1990 still works. “You write down a model; you assume it’s going to be ruled out,” Freese wrote in an email. “Can you imagine my surprise 25 years later that, instead, it fits the data well? Woo hoo!”
For more on such cosmological topics, you might enjoy our current planetarium show, Dark Universe, which runs daily in Morrison Planetarium. You can also swing by NightLife on Thursday, April 17th, and check out Universe Update live at 6:30, or take look for next month’s write-up here on the Science Today site or using our new app, available for both Android and iPhone.
Ryan Wyatt is the director of Morrison Planetarium and Science Visualization at the California Academy of Sciences.