And it can detect planets that don't transit their stars.
The approach was conceived 10 years ago by Harvard University astrophysicist Avi Loeb and Scott Gaudi, now an assistant professor of astronomy at The Ohio State University in Columbus, who took a cue from Albert Einstein.
One prediction of Einstein's theory of special relativity is that when an object is moving at a pace close to the speed of light, any light it emits appears more intense along the object's line of motion, forming a beam. To an observer watching the object approach, the light looks brighter than it would if the object were stationary.
The effect is most pronounced in powerful astronomical events such as gamma-ray bursts, in which matter emitting the gamma rays is accelerated to 99.9 percent of the speed of light, Dr. Loeb explains.
Indeed, to an astronomer looking directly into the beam, the effect can lead to the illusion that the light is traveling faster than its 186,000-mile a second speed limit. Such beams emanate from the poles of supermassive black holes that have gone on feeding binges. Researchers call them superluminal jets.
Loeb says he wondered if the effect were noticeable enough at slower velocities to use beaming to detect planets orbiting other stars. As a planet orbits, its gravity would tug the star to and fro. Perhaps the starlight would intensify slightly as the planet reaches the points along its orbit where it's pulling the star toward Earth.
After some back-of-the-envelope calculations to see if the question was worth pursing beyond the "I wonder if" stage, Loeb approached Gaudi, who calculated the intensity of the beaming effect for the types of stars that missions such as Kepler would examine.
"We estimated that it should be possible to detect it," Loeb says, although others were unconvinced.