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    Behold the Kepler Collection

    Kepler‘s planets, seen in silhouette, against their parent stars. The star colors — which are accurate — indicate temperature: the redder, the cooler; the bluer, the hotter. These are not images taken by Kepler, but are generated from Kepler data; measurements of the stars’ temperatures and distances help astronomers determine their luminosities, and once these are known it is an easy business to calculate the stars’ sizes. The planets’ sizes, as well as their paths across the faces of their parent stars, are determined by inspection of stars’ so-called “light curves,” which exhibit a decrease in stars’ apparent brightnesses as their planets pass between their stars and the Kepler spacecraft.

    The lonely star in the upper right of the image is the Sun, with Jupiter and Earth in silhouette, on the proper scale to the other stars and planets. Click here for a larger version; click on the image for a high-resolution (10 MB) version in which even the tiniest planets are plainly visible. Image source: Jason Rowe/NASA

    Are we alone?

    That’s what we want to know. And that’s what the Kepler mission and the fine image above are all about. From what we know about the requirements for life, the smaller the silhouette, the more likely that planet is to harbor life. At least life as we know it. It is on Earth-like planets that we believe life is most likely to form; life probably couldn’t exist on large gas balls like Jupiter, Saturn, Uranus and Neptune, because such planets form far from their host stars where liquid water cannot exist (although they can spiral in toward their parent stars over time). So it’s the little guys we’re most interested in. And we have good reasons to believe there are LOTS of them out there.

    Are we alone? Either way — yes or no — it’s pretty weird.

    Yes, we’re alone. In this whole vast universe, there is only us. As alone as alone can be, in a infinite sea of emptiness, cold, silence, and darkness (that’s what space is, really). I could try to explain to you just how alone we would be, but human language is no match for that job.

    No, we’re not alone. We are simply one living planet among hundreds or thousands or millions in our Milky Way alone. The human race is like a newborn child alone in an incubator, unaware of anything outside himself yet surrounded by literally billions of sentient beings. In this analogy it is unclear if we’ll even make it out of the NICU, but if we do we’ll eventually look back on our days in the incubator and hardly recognize ourselves.

    The truth is probably somewhere in between. There’s probably life out there, sure, but it’s most likely something like bacteria or a sponge and not like E.T. And if E.T. is out there, the chances of us contacting him (or him contacting us) is vanishingly small, unless the Milky Way is simply crawling and swimming and flying with life. For which there is — so far — zero evidence.

    In the meantime we are left with a question that, for all its scientific interest, has a clearly religious dimension. Just like everyone else, Christians like asking, “Are we alone?,” but for us the question means both more and less than it does to the non-theist or atheist. More, because whatever its answer, there’s more than science going on. We do not see the world merely in terms of matter in interaction, but also (and more fundamentally) in terms of faith, hope, and love. So the question carries that much more freight. Less, because in a sense we have already answered the question: We are not alone. God may seem terribly absent both in our personal lives and on the global scale; just ask the Psalmist. But, in the words of Sister Wendy (see below): “Reality is something very beautiful and strong. Something that takes suffering on board and is never sunk by it. Underneath all sorrow is joy.” And underneath all absence is presence. Faith is: We are not alone.

    But the scientific dimension of the question? We’re working on it. Witness Kepler and all its stars and little dark dots, each one presenting us with possibilities unimaginable. Data continues to pour in and we learn new things every day. Isn’t this an amazing place?

    Watch this space (harhar) for updates.

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    There are 1 Comments to "Behold the Kepler Collection"

    • Todd says:

      I love that graphic. I showed it to my class yesterday. We just happened to be talking about Kepler (the man). Gave me a chance to tell them about Kepler’s (the man’s) “observation” of Mercury transiting across the face of the Sun. Turns out it was probably a sunspot that he saw. But I bet Kepler the satellite hasn’t found any Mercury-sized planets! Of course, its looking a bit farther away than our Sun (by a factor of a WHOLE LOT).

      We didn’t explore the religious dimensions of this question, but the history of that topic is really interesting. The belief in a plurality of worlds populated by sentient beings was ONE of the things that got him in trouble with the Church. But then after Newton, in the heyday of natural theology, many people argued FOR the existence of extra-terrestrial life in part on religious grounds. I think the basic idea is that God, in his infinite power, wouldn’t have created just one group of sentient beings, but many (perhaps infinitely many).

      The arguments on either side weren’t very good. I’m not sure we can give arguments now that are much better. There are clearly VERY MANY planets out there, but as yet we have no real way to predict how common life will be, much less sentient life. It’s still all about speculation and philosophical assumptions. But it WOULD seem like a tremendous waste of spacetime if we were alone…….



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