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Tag: habitability
Depth Change: What Do the “Battleship” Aliens Want From Us, Anyway?
Seth Shostak is Senior Astronomer at the SETI Institute in California, and the host of the weekly radio show and podcast “Big Picture Science.”
Join Seth and 50 eminent scientists and sci-fi experts at SETIcon, to be held June 22-24 in Silicon Valley: www.seticon.org.
Battleship is not a film that Francois Truffaut would have made. Nor would any of those other namby-pamby European directors. Nope, this picture eschews that Continental obsession with small stories, set in quaint towns filled with pockmarked folk doing their banal things. Who cares?
No one, not when the fate of the Earth is in question. I’m proud to note that only the American film industry has the guts (not to mention the computer graphics horsepower) to fill the screen with a tale of ill-mannered aliens bent on incinerating the planet.
Consequently, Peter Berg’s film is pleasingly free of pretensions. It doesn’t waste your neural cycles exploring the uncharted labyrinths of the protagonists’ psyches, or anything overly Greek like that. It’s bad guys versus good guys, and the good guys win by being smarter, braver, and, in most cases, better looking.
The plot is exposed even before the main title settles in: NASA has found a planet that’s in the “Goldilocks” zone of its star—which is to say, it’s not too hot and not too cold for liquid water. It’s what astrobiologists would call a habitable world. Having found a possible home for E.T., the space agency beams up a signal that presumably informs any residents that Earthlings are friendly, and our planet is open for business.
Good News, Alien Seekers: E.T. Probably Doesn’t Need a Freaky-Big Moon Like Ours
Seth Shostak is Senior Astronomer at the SETI Institute in California, and the host of the weekly radio show and podcast, “Big Picture Science.”
The Moon is a ball of left-over debris from a cosmic collision that took place more than four billion years ago. A Mars-sized asteroid—one of the countless planetesimals that were frantically churning our solar system into existence—hit the infant Earth, bequeathing it a very large, natural satellite.
OK, that’s a bit of modestly engaging astrophysics. But some scientists think there’s a biological angle here. Namely, that elaborate terrestrial life might never have appeared if that asteroid had arrived a few hours earlier, and sailed silently by. Put another way, if every night were moonless, you wouldn’t be around to notice the lack of a moon.
But is that true? Did our cratered companion really make our existence possible?
The Ultimate Measure of a Planet—Habitability Isn’t a Yes/No Question
Seth Shostak is Senior Astronomer at the SETI Institute in California, and the host of the weekly radio show and podcast, “Big Picture Science.”
Back in the early days of “Star Trek,” whenever the Enterprise would chance upon a novel planet, we’d hear a quick analysis from Science Officer Spock. Frequently he would opine, “It’s an M-class planet, Captain.” That was the tip-off that this world was not only suited for life, but undoubtedly housed some intelligent beings eager for a meet-and-greet with the Enterprise crew.
But what is an “M-class planet” (also referred to as “class M”)? Clearly, it referred to a world on which intelligent life could thrive, and made it easy for the crew (and viewers) to see where the episode was headed. A recent paper by Washington State University astrobiologist Dirk Schulze-Makuch and his colleagues has suggested a somewhat similar way to categorize real-world orbs that might be home to cosmic confreres. Rather than giving planets a Spockian alphabetic designation, Schulze-Makuch prefers a less obscure, and more precise, numerical specification: a value between 0 and 1. A world that scores a 1 is identical to Earth in those attributes thought necessary for life. A score of 0 means that it’s a planet only an astronomer could love—likely to be as sterile as an autoclaved mule.
Schulze-Makuch computes this index—which he calls an Earth Similarity Index, or ESI—by considering both the composition of a planet (is it rocky and roughly the size of Earth?) and some crude measures of how salubrious the surface might be (does it have a thick atmosphere, and are temperatures above freezing and below boiling?) He combines parameters that define these characteristics in a series of multiplicative terms that are reminiscent of the well-known Drake equation, used to estimate the number of technologically adept civilizations in the Milky Way.
At present the number of worlds thought to have an ESI of 0.8 or greater—near-cousins of Earth—is only one: Gliese 581g (though that planet’s existence is disputed). But as additional data from NASA’s Kepler mission continue to stream in, we can expect that more such “habitable” planets will turn up. In particular, Kepler scientists reported this week on a newsworthy object called Kepler-22b. This planet is 2.4 times Earth’s diameter and in an orbit around a Sun-like star that places it securely in the habitable zone—where temperatures might be similar to a summer day in San Francisco.
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