Describe techniques that are currently being used to detect extrasolar planets and methods that could be used in the next decade or two to try and determine the atmospheric composition of these planets.

Looking for extrasolar planets is a difficult task, since the planets themselves are not bright, ie they dont emit their own light as stars do, therefore the only way they can be seen is by the light it reflects from the star that it is orbiting. Also, the planets are relatively tiny next to the huge size of the stars, and the brightness of the stars means that extrasolar planets cannot be seen with a conventional telescope. The main solution to this is to look at the effect the planets have on the stars they orbit, due to their gravitational force. Although the planet is small in comparison to the star, it will still exert a gravitational pull on the star. As the planet orbits the star, it will pull at it from different sides. If the star is watched for a very long time, the net effect of this gravitational pull is a slight wobble in the stars position. The amplitude of the …(short extract)