Scientists may have found the first planet located in another galaxy. The evidence is a little sparse but the search technique they're using is solid.
The idea is to use gravitational microlensing, in which a distant source star is briefly magnified by the gravity of an object passing in front of it. This technique has already found several planets in our galaxy, out to distances of thousands of light years. Extending the method from thousands to millions of light years won't be easy, says Philippe Jetzer of the University of Zurich in Switzerland, but it should be possible.