An effect predicted by general relativity and also known as frame dragging in which the orbit of a small body orbiting around a rotating massive one is slightly perturbed by the rotation. The effect was first predicted by Austrian physicists Joseph Lense and Hans Thirring in 1918. The possible detection of frame dragging around neutron stars has been tentatively reported by Italian astronomers in Nov. 1997. Stronger experimental confirmation of this effect was made using black hole observations by NASA's Rossi X-Ray Timing Explorer spacecraft.
The Lense-Thirring effect results in the orbital precession of X-ray emitting gas near the black hole, causing the X-ray emission to peak at periods which match the frame-dragging predictions.
