We are now heading in to the new year and there is a real buzz about the Internet, and it is all about finding extra-terrestrial life. NASA has a space probe called Kepler looking for extra-solar planets and the expectation of finding Earth-like worlds is getting pretty feverish. Below is an interesting video, detailing the findings of Kepler's first five discovered worlds:
If I had to bet on it then I think that if there is to be a discovery in the next few years of extra-terrestrial life then it will be Kepler that finds it. The most likely way, in my opinion, is through spectroscopy. It is possible to collect star light that shines through the atmosphere of a planet. This light will hold the signs we are looking for. When the light is split in to its spectrum (the colours of the rainbow) we observe absorption lines. These are black lines in the spectrum and they occur when the light has passed through a particular substance, so for example, the lines will appear at a certain point when the light has passed through oxygen, and different points for hydrogen. The practical upshot of this is that bu analysing these lines it is possible to detect what is present in the atmosphere of a planet. Things like methane, ozone, carbon dioxide are all produced by living things. This will not be definitive but might be a clue. What we really want to detect, however, is chlorophyll. Chlorophyll can only be produced by organic processes, meaning that its detection will be definitive. If we find chlorophyll then it's in the bag.
Keep up to date with Kepler. It is a very exciting mission. There has never been a better time to be an astronomer.
The hunt for chlorophyll is on.
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