Hi Kendra

there are a few ways you can find an extra-solar planet - here are two.

First of all, if you watch a star for a long time, and see that every so often there is a little dip in its brightness, which occurs in a regular way (say every few months) then you know that something is passing in front of it and blocking out some light - a planet, or maybe another fainter star (it can be hard to tell the difference, but usually if the dip is very small then it is a planet)

Secondly, you can look at the position of a star and see if it stays in the same place. If it is 'wobbling' a little then it means that something is pulling it, and that something could be a planet. You hear at school that the Earth orbits around the Sun, but in fact it is a bit more complicated than that! The Sun and the Earth are both orbiting around some position, just on the edge of the Sun, called the 'barycenter' (you could look this up on the web) - see

http://spaceplace.nasa.go.../kids/barycntr.shtml

so that means the sun is wobbling a bit too, mostly because the planet Jupiter is pulling on it! The same thing happens in other solar systems. So, we look at light from a star, to see signs of that star wobbling, and then we guess, or infer, that there is a planet tugging on it.

It is also possible - very rarely - to take a picture of an extrasolar planet . See

http://hubblesite.org/new...ve/releases/1998/19/