Re: Physics and Mathematics
Currently we can pretty much only detect planets in other star systems through one of two ways:
The gravitational wobbles these cause their star (not strictyly true as the bodies orbit around each other therefore the centre point of the orbit is not the centre of the star, although it will be close - same way that the centre point of the earth/moon orbit is not the centre of the earth) - however this is only currently detectable for large mass planets and requires a reasonable timeframe of measurement to record and detect the change in position over time - complicated by our own orbit. For example to detect a large mass such as Jupiter it would have to be closer to the star than Jupiter and rather faster moving because otherwise we would need to observe the plantary system for a sizeabable fraction of the planet's orbit period - Jupiter has an orbit of 12 years which gives an indication of the time periods required for observation.
The transit of a planet between the star and ourselves. This relies on both the system being aligned such that the planetary system is side on to ourselves (most won't be) and happening to being observing the star during the relatively short transit period and being able to measure the decrease in the star's observed output during this period and to perform this measurement a few times in order to remove any other reasons for the difference in the star's observed output.
We are getting better at such measurements and observations and as time goes by we are discovering, and confirming, the existence of more and more planets in other systems; and the size of these planets is getting smaller and smaller too as our measurements are getting more accurate and are over a longer period.
Biting the hand that feeds IT
