Technology Review: Blogs: arXiv blog: First extra-galactic planet spotted in Andromeda
Astronomers believe they may have detected the first planet outside our galaxy. Using gravitational microlensing, they were able to observe a star in the Andromeda galaxy for several days. Analysis of it's variability seem to indicate that it has a companion planet about 6 times the mass of Jupiter. Microlensing is a short-term effect so it can't be used to perform long-term observations of distant objects, but scientists believe it may be possible to detect extra-galactic Earth-mass planets using this technique.