Clearly, it is we—not black holes, not dark energy, not quasars—that are the strangest things in the cosmos.
By Paul Wallace, Religion Dispatches
As you probably know, a couple of weeks ago the Pope was in England smack-talking the atheists. What is generally less known is that, at the same moment that the Pope was having his say with the UK’s radical non-believers, Vatican astronomer Brother Guy Consolmagno, also in England, was busy talking about baptizing space aliens. Which, to me, sounded preposterous. But, after some contemplation, I’ve decided that it’s not preposterous after all.
Last week, a new planet—Gliese 581g—was discovered orbiting a star a mere 20 light years away in the constellation Libra. This in itself is not too big a deal, because the discovery of planets orbiting other stars (termed “exoplanets”) has become a weekly occurrence. But this planet is special because (1) it’s massive enough to retain an atmosphere, and (2) it resides squarely in the center of the so-called habitable zone of its parent star, red dwarf Gliese 581.
So far as we know (and that may not be very far, admittedly) liquid water is a requirement for life. And the habitable zone is a region surrounding a star within which water can exist in its liquid phase. Inside the habitable zone, close to the star, water boils. Beyond the habitable zone, far from the star, water freezes. Astronomers—wits ever—have come to call this region the Goldilocks zone (not too hot, not too cold…). It turns out that we live near the center of the Sun’s Goldilocks zone, and Venus and Mars also occupy it but sit close to its inner and outer edges, respectively. (If these planets’ atmospheres had evolved differently, they too would be able to support liquid water.)
The search for life on other planets has been ongoing for a long time, starting with the founding of the Search for Extraterrestrial Intelligence (SETI) Institute in 1959. Today, SETI is funded by private money and NASA funds an extensive Astrobiology research program. In its 2008 Roadmap, this program states the following as its first goal.
Understand the nature and distribution of habitable environments in the universe. Determine the potential for habitable planets beyond the Solar System, and characterize those that are observable.
The news about Gliese 581g is so big because it is apparently the first positive data point—outside the Solar System—in any future “distribution of habitable environments” in the universe. A big step forward for all of us who like to look up at the night sky and wonder: Are we alone?
Douglas Adams, in his Hitchhiker’s Guide to the Galaxy, wrote in all truth, “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.” What’s more, whether or not it reflects reality, there is an unavoidable psychological tendency to associate the small with the insignificant. This may be seen in the history of astronomy, which is a history of receding horizons. Scientists have often balked (and not always for scientific reasons) at many of these outward steps. Tycho Brahe, a well-known Danish astronomer of the late 16th century, rejected Copernicanism not only because it contradicted the Aristotelian physics of his day, but because it increased the size of the universe by several orders of magnitude. In Brahe’s view, Copernicus’ Sun-centered model expanded the gap between Saturn (at the time the highest of the planets) and the sphere of the stars to outlandish proportions. God, he reasoned, would not waste so much space. My point is that this objection had nothing to do with science and, to my mind, had everything to do with a basic human resistance to accepting that we are much smaller—and therefore much more inconsequential—than we would like to believe. The universe has grown enormously since Brahe’s time, and with every step the earth has become tinier, its inhabitants more inconsequential, and, paradoxically, more ignorant.
And with every outward step, as our universe and our ignorance grows, so do the number of potential space alien hideouts. So does the belief that there must be someone out there.
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