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Looking For Earth-Like Exoplanets
Discover Magazine is running a story detailing the search for planets like Earth orbiting other stars. While we've been able to locate a few "super earths" so far, none of them really compare in size or the potential for habitability with our own world. Fortunately, advances in data analysis and new space-based telescopes — such as Kepler, the James Webb Space Telescope, and the already-launched CoRoT (PDF) — have some astronomers predicting we'll find such an exoplanet by 2010, and a habitable one by 2012. Earth-based telescopes are also in the hunt, though the article notes, "even if a habitable Earth-like world is found first from the ground, it will most likely take a space observatory to search for the chemical signals that tell us what we really want to know: Is anything living out there? If the planet is one that can be observed transiting, it just might be possible to provide a hint of an answer in the next few years."
Obsessed with the fact we haven't observed something we can't yet detect... This must be some sort of mis-post.
...we've discovered the planet Krypton?
From what I understand from all the latest the tech news on /., we are going to have a super-awesome sci-fi future world in 2012.
Increase the rotational speed of the planet so much that the centripetal force counteracts gravity. Then, with giant nets, catch the oil as it floats up from the surface. Then, pump it through a hose and squirt it back to a giant funnel sitting outside earth. I mean, our only other alternative is NON-fossil based fuels, and that's just CRAZY!
Commodore64_love: I don't comprehend people who're so frightened of death that they'll bankrupt themselves to stay alive
It's harder than that. I assume by "see" you mean two-dimensional visible or near-visible light images. To produce images like that you have to be able to move each telescope in your interferometer (or have lots of them), in two dimensions. The big radio interferometers put the radio telescopes on train tracks. Some proposals for space interferometers put one on each end of a tether, spin them, then winch them closer and farther apart to trace out a spiral.
The other problem with crazy long baseline interferometry is that you need to transmit the received signal (including phase) between the individual elements. For radio that's not too bad because you can actually detect and record the phase, for low enough frequencies. For optical it's much harder.
Plus you have the problem that interferometers have great resolution but poor light gathering capability. They can't see things that aren't bright.
A back of the envelope calculation (which might be wrong) shows that a 50 km city at 50 light years would be about 2 x 10^-5 miliarcseconds. To get that kind of resolving power in the middle of the visible spectrum you'd need a telescope about 6000 kilometres across. That's not too insane. You might be able to pull it off with an array of a hundred or so reasonably sized space telescopes all orbiting around a L point somewhere. If you could collect enough light, and distinguish between the city light, the non-city planetary light and the star, of course.
Well, it seems to me that it's just a matter of perspective. We don't really see absolute values, we see deltas, and the baseline is the present.
Think of, say, dollars. Just saying "in year X you'll earn Y dollars a month" is only saying anything as a comparison. Whether it's in absolute dollar values, or "how much can I buy with it", the comparison only says much compared to your current lot in life. A 1960 standard of living would be luxury for someone from 1912 (think even just having antibiotics for a change), but would be a step back for you from 2008.
Or think of CPU MHz / Gigaflops / Gigabytes / whatever computer metric. "You'll have a computer with a 4 MHz CPU and 48 kilobytes RAM and a CRT" would have sounded like an awesome supercomputer in 1960 (they eventually landed on the moon with a weaker computer than that!) Have it in your home, all yours? Man, that would have sounded so unbelievably cool. Just think of what you'd do with all that raw computer power. But few people would even consider it a usable computer nowadays in 2008.
And I will postulate a _hypothesis_ that there must be a psychological "X times better than today" threshold, which drives those predictions. I don't know what that X might be. But there's a point where the "meh, who cares" factor of, say, predicting something 10% better next month, starts being the "that's awesome" of, say, predicting something 10 times better in 5 years.
E.g., think back when Moore's Law still worked that way, and you had, say, a 100 MHz Pentium. Predicting that you'll have 133 MHz in a few months, is uninteresting. Predicting you'll have a whole 1 GHz of CPU power in 5 years, now that would have gotten your attention.
So depending on which curve you are, and assuming it looks like infinite exponential growth ahead, the future (worth predicting) will always be Y years ahead. As in, "in Y years it'll be X times better than today." If you have the same X you aim for, the future will always be Y years ahead.
A polar bear is a cartesian bear after a coordinate transform.
A telescope at the Sun's gravity focus.
http://www.centauri-dreams.org/?p=785
(the comments contain some interesting information as well.
The resolving power is a bit of slippery subject, because gravity microlensing doesn't work quite like a regular refractive lens. According the the comments, you can basically see anything, no matter how far away (subject to caveats when you start getting insanely far away) as if it were in close orbit around the sun. So the resolution you can obtain really depends on what kind of telescope you put out at the gravity focus. One of the commenters calculated that if we put Hubble out there we could see things about the size of Mercury, at ANY distance. The light collecting ability is also enormous.
There are some problems though. First, you have to get out there. Farther than anything we've ever sent. Also, 550 AU (about 20 Pluto distances) probably won't work, because then the light you're collecting has to skim the surface of the sun. Better would be to go out to about 1000 AU (about 1/200th of the way to Alpha Centauri) so that you're not trying to see through the thick parts of the sun's atmosphere.
Once you get there, you have to be able to accurately record smeared out images while staring into the sun.
Finally, you can really only look at one thing. If you want to look in a different direction, you have to move the probe a LONG way. These would probably be single purpose missions, which means you'd basically have to know exactly what you wanted to look at before you sent out the probe.
We use microlensing caused by other objects all the time though. There's even a project to look for extrasolar planets that happen to be revealed by microlensing events.