Detecting vegetation, analyzing atmospheres on extrasolar planets

Edward Willett @ 05-12-2007

sodiumlinesWe know there are lots of planets orbiting other stars: we’ve found more than 250 of them already, and we’re getting better at finding them all the time. But the big question is, do any of the obviously plentiful extrasolar planets in the galaxy support life?

So far, we can’t tell: but we’re getting closer to being able to. Dr. Luc Arnold of the CNRS Observatoire de Haute-Provence in France thinks we might be able to tell if an extrasolar planet supports vegetation via a spectral analysis of the light reflected off it, because vegetation absorbs a lot of light around a specific wavelength for use in photosynthesis (on Earth, that’s red light, so this phenomenon is called the Vegetation Red Edge).

We don’t have any Earth or space-based telescopes that are able to carry out spectral analysis fine-grained enough to do this, yet, and even ESA’s Darwin and NASA’s Terrestrial Planet Finder, launching within the next decade or so, won’t be able to–but the next generation of planet-finding spacecraft after that probably will be.

One thing we have managed to do, though, is analyze the atmosphere of an extrasolar planet: a "hot Jupiter" orbiting a star in the constellation Vulpecula. By measuring which wavelengths of light from the planet’s star are absorbed by its atmosphere every time it swings between the star and Earth, University of Texas at Austin astronomer Seth Redfield determined the planet’s atmosphere contains sodium. (Via Universe Today and Universe Today.)

Again, we’re a long way from using the same technique to look for oxygen–a strong indicator of Life As We Know It–in Earth-sized planets’ atmospheres. But it’s likely just a matter of time. (Illustration: S. Redfield/T. Jones/McDonald Observatory.)

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A Personal Note: I apologize for a lack of posts from me over the past little while. As Paul mentioned in his last Friday Free Fiction post, I’m currently in rehearsal for a professional production of Beauty and the Beast, and it’s taking up most of my time. I hope to still manage an occasional post, though, until the show ends December 30, and resume regular posting in the new year.

[tags]astronomy, extrasolar planets, extraterrestrial life[/tags]

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4 Responses to “Detecting vegetation, analyzing atmospheres on extrasolar planets”

  1. Mike / Science-News.org says:

    Good post. I think that with the upcoming “Giant Magellan Telescope” and the other very large and extremely large telescopes planned (as they are called), we will be able to better detect these signatures.

    The GMT is already being built and should be done by 2016. I forgot the exact number but the telescope should have the equivilant to a 20-24m mirror to collect light.

    That’s incredible. I think this telescope combined with the TPF will give us our real first hints at a possible earth-life planet’s atmosphere.

  2. Arvind says:

    Life on Earth can be considered a freak event of consciousness manifesting itself beyond natural surroundings . Thus , the same (super) consciousness might reveal itself in any other form in some part of the expansive universe . We cannot narrow that same human or likewise will have to be detected . It could just be another form . And we might need a 7th sense to detect that !

  3. Science-News.org says:

    That’s true Arvind. Life could take the form and shape of anything. It doesn’t need to be carbon based. Life could take the forum of electrical impulses, maybe it resembles metal, or it life could take the shape of boulders.

    Although life may not be human elsewhere if there is other life in space there is a good chance there are many life forms and some of those may take biological forms like us humans. Or at least have similar systems.

  4. Science-News.org says:

    That’s true Arvind. Life could take the form and shape of anything. It doesn’t need to be carbon based. Life could take the form of electrical impulses, maybe it resembles metal, or it life could take the shape of boulders.

    Although life may not be human elsewhere if there is other life in space there is a good chance there are many life forms and some of those may take biological forms like us humans. Or at least have similar systems.