Earth as Alien Planet

by Clifford Johnson     Department: Earth

One of the  most striking things about the writer Greg Bear's "Anvil of Stars", a novel I read many years ago, was the idea of keeping quiet. Who keeping quiet? An entire planet. He plays rather nicely with the idea that once you become an advanced enough civilization to be a little more mature about things, maybe one of the smartest things you can do is spend a bit of effort  making yourself and your planet as uninteresting as possible to the  outside eye that might be looking for resources to snatch away from you. (It's not like we have not seen this before on our own planet again and again.) So, for reasons I won't go into now, there's a lot of discussion of the various means that a civilization might go to to hide that they're advanced, and perhaps to hide that they live on a resourceful planet.

As a result of casting my minds' eye over those books of Bear's I'd read (last week after spotting Damon's post on the interview with him)  I was reflecting about this  whole issue. Then my eye ran to the bottom of our blog, where
 there are titles of recent posts done over on the WIRED Science blog (not to be confused with Correlations, which is the official WIRED Science blog - got that? The former is the Science blog of the magazine WIRED; We're the blog associated to the TV show). There, I spotted this post (by John Borland) on a closely related issue. This is the ongoing exciting journey of discovery of extrasolar planets. Planets around other stars - other solar systems, if you like. There's a huge amount going on now, with new planets being discovered very regularly. I've you've not been following what has been going on, I strongly recommend catching up on the story, as it is very exciting. A good source of the recent history of the subject, with interviews with several of  the people who perfected the delicate techniques required to find  the planets can be found in the History Channel's series "The Universe". The opening episode of their recent second season was all about it. (They'll repeat it soon, so check their schedule.)

There's been a variety of  planets found by now. Have a look at an article that summarized some of them that I pointed to in the post "Otherworldly Top Ten" over on Asymptotia a while back. The detection methods currently used are indirect. We have no technology to "see" these planets directly, and so the delicate technique that I referred to before involved looking at the planet's effects on its star - it makes it wobble slightly, and from the wobbling, you can infer some things about the bodies that are in orbit about it.

Obviously, this is not going to tell you a lot about the planets. At most you can work out how big they are and  how far out from the star they are orbiting. From knowledge of the properties of the star itself, you can then make guesses (albeit educated ones) about what conditions on a given planet might be. It is an extremely useful technique, with remarkable results still coming in, but would it not be nice to actually image a planet directly? If part of the motivation for all this is to find planets that are more earth-like (and therefore rather small in the scheme of things, as well as in the "Goldilocks" area around a star - not to hot, not too cold, at least as regards life as we know it), we'll need more direct detection techniques to study aspects of the atmospheric conditions.  Well, there are telescopes being planned right now that will be able to do that, and you can learn more about preparations for them in the WIRED Science article, which has as its focus the recent findings of scientists (MIT's  Sara Seager, and the University of Florida's Eric Ford, and Enric Palle and a team at the Instituto de Astrofísica de Canarias, in Spain) about how our very own earth might look as viewed from far away. Even if it was so tiny in the image as to only light up one pixel, how much might an alien civilization be able to deduce about us from just that information? (Maybe quite a bit - periodic dimming and brightening of the pixel can signal information like weather patterns - from cloud motion - and the length of the day, for example.)

Have a read of the article. Enjoy!

-cvj

Tags: astronomy, planets, science fiction