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Earth Space Science

Odds Favor Discovery of Earth-Like Exoplanet in 2013 90

Posted by timothy
from the awaken-the-sleeping-giant dept.
Earth-like exoplanets have gotten a lot of attention in the last few years; it's exciting to think that there's life — or even just life-sustaining conditions — on planets other than Earth, whether near by (on Mars) or much farther away (orbiting Vega). Projects like NASA's Kepler, and the ground-based HARPS, attempt to spot planets outside our solar system of all kinds. These exoplanet discoveries have been ramping up lately, and so has sorting of the discovered planets by size and other characteristics; the odds are looking good, say astronomers quoted by Space.com, that an Earth-like planet will be found this year. Abel Mendez runs the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, and UC Berkeley astromer Geoff Marcy looks for planets as part of the Kepler team; they explain in the article why they think 2013 is an auspicious one for planet hunters.
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Odds Favor Discovery of Earth-Like Exoplanet in 2013

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  • Sure we do (Score:5, Informative)

    by Immerman (2627577) on Sunday December 30, 2012 @12:46PM (#42426511)

    Getting to other stars isn't actually terribly difficult, as far as we can currently tell. Only getting there quickly presents a problem. Build a large, self-sufficient "space station"/world-ship, accelerate it to say 0.1% of light speed (only about 20x faster than Voyager 1), and then wait for a few thousand years until it reaches it's destination. Sure, accelerating it with current technology gets really expensive really quickly, and it'll be the distant descendents of the original crew who reach the destination, but the only real difficulty is creating a long-term viable self-contained ecosystem. And considering that the one serious attempt we've made, Biosphere 2, was actually remarkably successful for a first attempt, we could probably have that problem licked within a few decades if we really wanted to. All we'd need is some sufficiently motivating reason to do so, which is where the real problem lies.

    Quite similar to getting to the moon actually - basic rocketry technology has been around for almost a thousand years, but it wasn't until we got into a technological pissing contest (aka The Cold War) with Russia that we actually got off the planet and eventually to the Moon. We've never returned because, well, why would we? There's nothing there worth the expense of the trip, and until we reach a point where its tactical or strategic value is worth the expense it's only the dreamers and visionaries that appreciate its value, and sadly they don't control near enough wealth to make it happen.

  • Outdated technique (Score:5, Informative)

    by Immerman (2627577) on Sunday December 30, 2012 @01:41PM (#42426827)

    Not really - the atmosphere is an incredibly thin skin around a rocky planet and it's composition can only be detected by the use of *extremely* sensitive instruments. Imagine passing a pea in front of a street light several miles away - it'll be *far* easier to detect the shadow of the pea than the condition of its skin.

    And actually that's a rather obsolete method for detecting planets - you can only detect those whose orbital plane happens to intersect the Earth - a tiny percentage since the alignment is more or less random. More modern techniques detect planets via the wobble they introduce in the motion of their parent star - for example our sun actually orbits a point lying about 1/2 to 2 solar radii away from its center - the barycenter (center of mass) of our solar system, which constantly changes as the massive outer planets move through their orbits. Our own planet introduces a much smaller (since we're far closer and less massive) but higher frequency (since our year is much, much shorter) wobble as well. By detecting similar wobbles in other stars we can make a good estimate about the masses and distances of its planets, and the planet doesn't have to pass directly between its star and us to be detected, allowing us to detect far more planets.

    Analyzing atmospheric composition is more challenging, and I believe current techniques are limited to planets that pass directly between us and their star - essentially a planet with no atmosphere will dim the light slightly as it blocks a tiny percentage of it, an atmosphere will also introduce a *very* tiny spectral shift since some of the starlight that reaches us will have passed through the planet's atmosphere and been partially absorbed based on it's chemical composition. Theoretically a similar technique could be used for out-of-plane planets by analyzing reflected light, but our current instruments aren't nearly sensitive enough to distinguish between the miniscule amount of light reflected from a planet and the raging inferno of its star. Even if we could, it would likely be extremely difficult to distinguish between the spectrum shift introduced by the atmosphere and the shift introduced from surface reflection.

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