posted on May, 2 2014 @ 01:47 PM
originally posted by: Ross 54
The apparent spectroscopic detection of a combination of oxygen and methane on an exoplanet planet may not be indicative of life, as has been
supposed, three scientists say. They aver that a sterile world could have oxygen alone and its moon methane alone, and that the two could not be
distinguished, leading to a false indication of life.
Either gas alone is apparently not considered sufficient evidence for life. Interesting but I wonder if it's probable that an Earth sized planet in
its star's habitable zone would have a moon with enough gravity to retain a substantial atmosphere. Even Earth's exceptionally large Moon doesn't.
They totally misunderstood this paper.
That's not what it says at all.
What it says basically is that we can't be sure that the oxygen or methane is coming from the planet or coming from an exomoon with current
The false positive is that such a biosignature would be coming from the planet's moon rather than the planet. The oxygen biosignature would still be
there. We just wouldn't be able to distinguish whether it came from the planet or the planet's moon.
Finding both Oxygen and Methane on a world would be exciting. What this paper tells us is that finding both doesn't mean they both come from the
planet. One could come from the planet, the other from the moon.
However, what is not said in the article is that just finding the signature of oxygen in the first place would also be exciting.
Because there is nothing which replenishes oxygen in the atmosphere of an exoplanet which we know of other than life. Oxygen likes to bond with other
elements so finding a lot of O2 (Oxygen) and/or O3 (Ozone) in spectrum like this will still tell us a planet probably has photosynthetic life
Methane (CH4) would be the result of bacterial and animal life if seen in combination with the Oxygen so finding both would be more exciting but
finding a world with just Oxygen but not sure whether the Methane is from a moon would also be exciting.
If we find a world with a bunch of free oxygen in its spectra it's probably due to life.
Whether that spectra is a result of the planet or a habitable moon doesn't matter other than to us scientist who want to know where what we're looking
at came from.
By the way, all of this gets easier with planets around lower mass (K and M) stars than our Sun (a G star). So what this says is that with current
technology we should not limit ourselves to just looking for biosignatures on Earthlike planets around stars like our Sun but should focus on Red
Dwarfs (M stars) and Orange (K) stars.
edit on 2-5-2014 by JadeStar because: (no reason given)