What ET might see looking at us
In a new study, planetary scientists determined what extraterrestial aliens might see if they were peering at Earth through telescopes. The researchers, from MIT, the Instituto de Astrofísica de Canarias, and University of Florida, based their analysis on telescope technology expected to become available in the next few years. Even with those systems, designed to find extra solar planet, Earth would be represented just by a single pixel of light when viewed from another world outside our solar system. From the MIT News Office:
According to their analysis, among other things E.T. could probably tell that our planet's surface is divided between oceans and continents, and learn a little bit about the dynamics of our weather systems.Link
"Maybe somebody's looking at us right now, finding out what our rotation rate is -- that is, the length of our day," says Sara Seager, associate professor of physics and the Ellen Swallow Richards Associate Professor of Planetary Sciences at MIT...
"The goal of [our] project was to see how much information you can extract" from very limited data, Seager says. The team's conclusion: a great deal of information about a planet can be gleaned from that single pixel and the way it changes over time...
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The alien measurements that are suggested by the article are based on projections of the technological abilities of our own instruments over the next few years.
An alien race, of course may be hundreds, thousands or millions of years ahead or behind us in terms of the technological ability.
The laws of physics however, which as far as we understand apply universally, may apply certain restrictions on their capabilities (essentially curtailing a Moore's law of instruments) that mean that they may not be able to observe us in much greater detail that by which we can observe them.
hopefully they're not advanced enough to see the pimpstar rim ad in the above post.
pimpstar rims = alien technology
They'll take one look at us, and put a comment down in the log book..."Mostly Harmless"... and move onto more interesting things to look at.
Aye... mostly harmless we are.
and some of the sheep
> The team's conclusion: a great deal of
> information about a planet can be gleaned
> from that single pixel and the way it
> changes over time
This is true, but it's important to remember that while we're looking at a single pixel, we're also NOT jst looking at a single pixel.
What do I mean? The light intercepted by that single pixel is generally not recorded as 'electron counts per RGB sensor well', as is the case in, for instance, digital cameras.
Rather, the light is fed through a spectrophotometer, which allows us to see not just how MUCH light s recorded at that pixel, but how many photons ('electron events') are recorded by that pixel at each wavelength. Thus, we can see things like emission/absorption lines in the received light, and match those wavelengths to specific elements, molecules, etc. Coupled with the more crude-but-still-useful measurement of raw intensity, this is what gives us the ability to infer tremendous detail from a single pixel.
(pedantic mode OFF)
Don't forget that the light is probably a few hundred/thousand years old. The pixel you are looking at could have been wiped out by an asteroid(or other nasty galactic event) by the time the light reaches you.
President Bush killed NASA's stellar-occluding coronagraph telescopes, the Terrestrial Planet Finder (TPF-C) and an even more capable interferometer (TPF-I). Both would be capable of finding Earth-like planets with oxygen and liquid water several dozen light-years away.
In 1999, those projects were being actively developed, but the most important project of the entire human race -- finding another place to live -- is not a priority for the Bush administration.
Now the only place those telescopes exist is in JPL's "Explorer Island" sim in Second Life. They are really amazing models, too. If you go inside the TPF-C, you can see the entire optics path including the occluding and sidelobe dots inside the optics box.
Last I heard, TPF-I hadn't really been cancelled, but rather, it had never been approved, and was undergoing further study by the folks at NASA and JPL. Its originator, Web Cash of the University of Colorado, was a professor of mine a few years ago.
If it has been officially relegated to the dustbin of good-ideas-that-should-have-been, it would be a shame. I recall listening to him relating the idea to us in class one day, and then, later, having him give his presentation about it to our campus astro club. It's a remarkable idea, and very, very promising.
While I am a fan of human spaceflight, it's a shame to see budgetary constraints forcing NASA to choose human spaceflight or remote observation missions. As always, I'd rather my tax dollars were spent on research instead of fruitless wars.
#10: What, so wars over banana fields or apricot orchards are just fine??? Hmpf!
#11: No, but there are just wars. Can anyone deny that going to war to stop the Jpanese and Germans was a Good Thing? That doesn't make that war nice, but it was just.
Oh, and a correction to my post #7: 'spectrometer'/'difraction grating', rather than 'spectrophotometer'.
This very interesting article also assumes that there is a alien world with technology at least as advanced as ours, who have eyes, who can observe visible light, who care about astronomy, who care about SETI? For all we know the universe is filled with advanced civilizations who use echolocation, who live exclusively underwater, whose skies are completely beclouded (like Venus)? THINK ABOUT IT!
Well then, I suspect that we are going to come as quite a shock to them when our invasion fleet arrives.
Any aliens reading this blog, we're not with RyanH @14, okay? He just declared war on you all by himself, it's nothing to do with the rest of us, so aim your pre-emptive retaliation just at him, please.
I shop at the Aliens R Us store.