Exoplanets

It turns out that other solar systems are not shedding much light on how ours came to be: But as the menagerie of young planetary systems grows, researchers are struggling to square their observations with current theories on how our Solar System and others formed. Such ideas have been in turmoil ever since astronomers started discovering planets around distant stars — a list that now numbers in the thousands. The Solar System has rocky planets near the Sun and giant gas balls farther out, but the panoply of exoplanets obeys no tidy patterns. And the rule book for world-building is getting more complicated as researchers find evidence of planets in the process of being born. Still, astronomers hope that witnessing Read More ›

That’s a common problem when we ask great figures their opinion about things they haven’t studied. From a review of Stephen Hawking’s (1942–2018) last book (or the last book that could be put together plausibly under his name), Brief Answers to the Big Questions: Because of the likelihood of a nuclear confrontation or an environmental catastrophe, we should work out how to leave the planet and colonise space, Hawking reckons. “Spreading out,” he says, “may be the only thing that saves us from ourselves.” He concedes that move will involve abandoning the flora and fauna of Earth, but Hawking seems to believe that humans deserve more of a future than other species. Leaving all other life to fend for itself is Read More ›

An MIT astronomer is 75% certain that an object previously suspected of being an Intro of exomoon (a moon orbiting an exoplanets) really is that: The first confirmed detection of an exomoon would mark a milestone in exploring planetary systems throughout the Galaxy. It would, among other things, allow scientists to test ideas of moon formation using examples from beyond the Solar System. Teachey’s proposed exomoon is already throwing up some surprises. Evidence suggests the moon is about the size of Neptune, orbiting a planet roughly the size of Jupiter. That would make it unlike anything in the Solar System, where most moons are much smaller than the planets they orbit. “It’s raising new questions about the dynamical processes that Read More ›

Suggested at New Scientist: There may be life out there that was like life on Earth when Earth was a very different environment: In the 4.5 billion years our planet has existed, it has experienced dramatic transformations: ice ages and warming periods, times when the atmosphere was impossible to breathe, when large areas were desert, or when lush tropical forests hugged the poles. Throughout the vast majority of this turbulent history, life has somehow clung on. If, armed with a spotters’ guide to the world we inhabit today, we found exoplanets resembling those early Earths, would we even recognise them for what they were? Maybe not. We know how to seek comparatively advanced signs of intelligent life, such as cacophonous Read More ›

Plus, a friend offers a reply. From ScienceDaily: There may be more habitable planets in the universe than we previously thought, according to Penn State geoscientists, who suggest that plate tectonics — long assumed to be a requirement for suitable conditions for life — are in fact not necessary. When searching for habitable planets or life on other planets, scientists look for biosignatures of atmospheric carbon dioxide. On Earth, atmospheric carbon dioxide increases surface heat through the greenhouse effect. Carbon also cycles to the subsurface and back to the atmosphere through natural processes. “Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment,” said Bradford Foley, Read More ›

From SETI’s Seth Shostak, who surely doesn’t welcome this news, at NBC: A recent paper by three researchers at the University of Oxford is throwing shade on those who feel confident that the cosmos is thick with extraterrestrials. … If we own up to the true extent of these uncertainties and do the requisite math, the Oxford study finds that there’s at least a 53 percent chance that we’re alone in the Milky Way and at least a 40 percent chance that we’re alone in the visible universe. Homo sapiens could be the smartest thing going. This result, they claim, melts the Fermi Paradox like butter on a hot griddle — maybe no one has colonized the galaxy because no Read More ›

From Ethan Siegel at Forbes: Based on everything we know, it seems like the conditions that make life possible are a lot more diverse and flexible than most people would expect. … Take Earth’s large moon, for example. The gravitational forces from it keep our planet rotating on the same axis over time. Our present axial tilt is 23.5 degrees, but this will vary over very long timescales between 22.1° and 24.5°. A world like Mars, on the other hand, has almost the same axial tilt as Earth: around 25°. But over tens of millions of years, this will vary by ten times as much as it does on Earth: from a minimum of 13° to a maximum of 40°. Read More ›

From Maria Temming at Science News: New infrared telescope observations reveal an exoplanet that appears to be growing inside the disk of gas and dust around a star about 370 light-years away. Astronomers have indirectly identified other exoplanet embryos by observing the paths that these young worlds cleared through the dusty disks around their parent stars (SN Online: 11/6/14). But pictures released July 2 of the newly discovered exoplanet, dubbed PDS 70b, give the first clear visual of a still-forming exoplanet itself, seen as a bright splotch of light off to the side of its host star. But beyond that, we don’t know much: These observations revealed PDS 70b to be a giant, cloudy world about as far from its Read More ›

The reality that earth is fine-tuned for life screams out at us from stories that seem to make a point of not emphasizing the fact. From ScienceDaily: The researchers suggest that Kepler-186f’s axial tilt is very stable, much like the Earth, making it likely that it has regular seasons and a stable climate. The Georgia Tech team thinks the same is true for Kepler-62f, a super-Earth-sized planet orbiting around a star about 1,200 light-years away from us. How important is axial tilt for climate? Large variability in axial tilt could be a key reason why Mars transformed from a watery landscape billions of years ago to today’s barren desert. “Mars is in the habitable zone in our solar system, but Read More ›

From Matt Williams at Universe Today: For decades, scientists have believed that there could be life beneath the icy surface of Jupiter’s moon Europa. Since that time, multiple lines of evidence have emerged that suggest that it is not alone. Indeed, within the Solar System, there are many “ocean worlds” that could potentially host life, including Ceres, Ganymede, Enceladus, Titan, Dione, Triton, and maybe even Pluto. But what if the elements for life as we know it are not abundant enough on these worlds? In a new study, two researchers from the Harvard Smithsonian Center of Astrophysics (CfA) sought to determine if there could in fact be a scarcity of bioessential elements on ocean worlds. From a recent email from Read More ›

From Lisa Grossman at ScienceNews: If you’re looking for starry skies, exotic plant life and extreme weather on your summer vacation, NASA’s Exoplanet Travel Bureau has just the spot. Consider a trip to Kepler 186f. This extrasolar planet is nearly 558 light-years away, so a real trip may be out of your budget — and astronomers aren’t sure if the sphere even has a life-sustaining atmosphere. But NASA’s Exoplanet Exploration website offers a virtual tour of what visiting the alien world might be like. More. Hey, don’t miss out on these artist’s impressions. The way things are going with the search for ET, humans, our domestic pets, menageries, and sanctuaries may be the first and only life these countless inhabitable Read More ›

Suzan Mazur has republished her wide-ranging interview with the Renaissance man (in an age of specialization), first published in Omni in 1981, at Oscillations. The interview as a whole offers insights on how space exploration was viewed back then (for example, habitable planets were not top of mind): Suzan Mazur: Since every last mineral can be found in space fiftyfold, do you think a principal aim should be to recapture the vision of space exploration that we quickly abandoned after we landed on the moon? Malcolm Forbes: These high frontiers are surely exciting, but whether it’s economical to go there to support the Earth’s population, I’m not sure. I think it more immediately feasible to concentrate on the planet we Read More ›

From Lisa Grossman at ScienceNews: Seven of those exoplanets are in the TRAPPIST-1 system, one of the most exciting families of planets astronomers have discovered to date. At least three TRAPPIST-1 planets might host liquid water on their surface, making them top spots to look for signs of life (SN: 12/23/17, p. 25). Yet those planets shouldn’t exist. Astronomers calculated that the small star’s preplanet disk shouldn’t have contained enough rocky material to make even one Earth-sized orb, says astrophysicist Elisa Quintana of NASA’s Goddard Space Flight Center in Greenbelt, Md. Yet the disk whipped up seven. TRAPPIST-1 is just one of the latest in a long line of rule breakers. Other systems host odd characters not seen in our Read More ›