Tightening Life’s Belt?

New research rethinks the possible prevalence of life in the Universe, suggesting that our asteroid belt—as disrupted by the gravitational influence of Jupiter—played a key role in seeding the Earth with water and organic compounds. Unable to coalesce, and situated around the solar system’s “snow line,” the belt provides millions of little ice trays which come smashing into the Earth on occasion. On Starts With a Bang, Ethan Siegel says “getting struck by asteroids can introduce new organics and materials into the ecosystem, and can knock off the apex animals of the time, paving the way for new species to mutate and fill niches.” Research shows that an asteroid belt like our own develops in only 4% of planetary systems, but it’s too soon to say if it’s really a prerequisite for, say, humanity.


Out of Reach Real Estate

The Milky Way panorama by European Southern Observatory

Steinn Sigurðsson recently spent a weekend considering exoplanets and extraterrestrials at the Second SETI Conference in California.  He writes, “It is important to remember that while science and discovery is important, it is not the ontological basis for space exploration. Space is, ultimately, about existential motivations.”  In other words, we wouldn’t mind finding a friend, or a new Earth to colonize when this one gets fried by the sun.  As Kepler continues to increase the number of known planets in the galaxy, it may only be a matter of time.  And exoplanetary science is in its infancy.

On Starts With a Bang, Ethan Siegel writes “the Universe is an extremely diverse place, where every combination of planets and solar systems we can think of very likely exist.” The star system Kepler-36, for example, features two planets in such close orbits that every 97 days, one rises like a massive moon in the sky of the other. But that’s still not near enough for Ethan, who wants to escape Earth’s gravity well without rocket fuel. He could float over to Neptune if it were 1,000 miles away—but the Earth would also be torn apart.  That’s called a minor detail.

Four First Glimpses

When the stars align, the results can be nothing short of spectacular. On Starts With a Bang, Ethan Siegel shows us an “Einstein ring” photographed by the Hubble Space Telescope. This celestial halo surrounds a massive red galaxy, and is in fact light from a much more distant galaxy focused by gravity. Ethan explains, “gravity will bend spacetime, forcing light into a curved path. If a very distant galaxy is properly lined-up with us and a less distant—but very massive—galaxy, its light will not only be bent into a ring if the alignment is perfect, but its light will be greatly magnified, making a dim galaxy appear very bright.” The newly-imaged LRG 3-757 “makes about 80% of a full ring: a cosmic horseshoe.” A never-before-seen galaxy is also visible on Greg Laden’s Blog: GN-108036. Greg says this galaxy produces stars “at the rate of about 100 per year. In contract, the Mikly Way (our galaxy), even though it is 100 times bigger in mass than GN-108036, produces about 30 new stars per year.” Amazingly, we are seeing this galaxy as it existed only 750 million years after the big bang. Greg also has the first low-altitude images of the massive asteroid Vesta, taken by NASA’s Dawn spacecraft. And on Starts With a Bang, Ethan covers Kepler’s discovery of the first exoplanet smaller than Earth, whose very hot year is shorter than a week.

Kepler Doubles its Prospects

The planet-hunting spacecraft known as Kepler has detected the first definitive exoplanet in a binary star system, and lead author Dr. Laurance Doyle has all the details on Life at the SETI Institute. He writes, “Perhaps half the stars in the galaxy are in double star systems. Understanding that planets can form in close binary systems means that these, too, can be targets in the search for habitable worlds.” The twin stars have a combined mass less than that of our sun—and the planet is the size of Saturn, in an orbit as close as Venus. Fellow SETI Astronomer Dr. Franck Marchis writes, “There is no equivalent in our solar system of such a large and dense exoplanet. Kepler-16b has the same size as Saturn but a higher density, suggesting that it could be made of a core of ice/rock (half its size) surrounded by an atmosphere in a configuration similar to Saturn.” In other words, having two suns doesn’t automatically make a planet hot, sandy, and full of Jawas. It’s all about orbiting in that “Goldilocks” zone, where the temperature is just right.

What Makes a Planet?

Greg Laden draws our attention to an object named Vesta, which by itself makes up 9% of the asteroid belt. Greg says “if you take the largest handful of objects in the asteroid belt, Ceres, Vesta, Pallas and 10 Hygiea, you’ve got half of the mass of the entire thing, according to the most current estimates.” According to NASA, Vesta is even differentiated, meaning it was once hot enough to form a core, mantle, and crust. On Life at the SETI Institute, the Analysis Lead on NASA’s Kepler project explains how to spot a planet from hundreds of millions of miles away. Dr. Jon Jenkins says “We’re looking for one part per 10,000 drop in brightness caused by this tiny planet blocking a small fraction of the light from the star.” Kepler finds about ten new planetary candidates every day, and can also “hear” starquakes, the “songs of the stars.” Finally, on Starts With a Bang!, Ethan Siegel brings planetary dynamics closer to home. He says earthquakes occur as the planet differentiates itself, bringing the heaviest elements to the core, and the lightest elements to the surface. Every time this happens, the world spins a little faster.

Astro News Near and Far

On Life at the SETI Institute, Dr. Franck Marchis shares the latest results from Kepler, a telescope in an Earth-trailing heliocentric orbit which keeps a distant eye on 156,453 stars. Kepler watches for tell-tale reductions in brightness, which “could be due to the transit of an exoplanet passing between its star and us.” As of Tuesday, Kepler has identified 1202 likely new exoplanets, tripling the number of known worlds beyond our solar system. These results suggest that out of the 200 billion stars in our galaxy, “several hundred million of them could have an exoplanet with a surface temperature adequate to sustain liquid water.” Great, now where’s our hyperdrive? Ethan Siegel also reports that Hubble has detected a galaxy at a record-breaking redshift of 10.3, making it the most distant galaxy ever observed. If it still exists, it’s probably full of planets too.