“Frame-dragging,” one of the last untested predictions of general relativity, has been confirmed by the first reasonably accurate measurement of how the rotating Earth warps the fabric of space.

Researchers charted the path of two NASA satellites over 11 years with laser range-finders with the precision of a few millimeters. The effect dragged the satellite’s orbits out of position by about 2 meters each year, the researchers report in this week’s Nature.