Janek Kozicki writes "It has been long thought that dwarf galaxies orbiting Andromeda galaxy (M31), or any other galaxy for that matter, are distributed more or less randomly around the host galaxy. It seemed so obvious in fact that nobody took time to check this assumption. Until a 15-year-old student, Neil Ibata, working with his father at the astronomic observatory, wanted to check it out. It turned out that dwarf galaxies tend to be placed on a plane around M31. The finding has been published in Nature. Local press (especially in France) is ecstatic that a finding by a 15-year-old got published in Nature. However, there's another more important point: what other obvious things didn't we really bother to check?"