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How Einstein's theory of special relativity helped find a new planet (+video)

To find the planet, astronomers used Einstein's theory as it pertains to the intensity of a beam of light. The method could add more exoplanets to a growing list, no 'wobble' or 'transit' required.

By Staff writer / May 14, 2013

Kepler space telescope is designed to search for Earth-like planets in the Milky Way galaxy. The telescope has been in space since 2009, but scientists keep finding new ways to use it — even using special relativity — to find extra-solar planets.

Courtesy of NASA / AP

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With a little help from Einstein's theory of special relativity, astronomers have discovered a planet orbiting a star some 2,000 light-years away using a new approach that was barely a gleam in its proposers' eyes a decade ago.

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The planet is a bit larger and about twice as massive as Jupiter. It orbits its sun-like star once every 1.5 days. The team making the discovery estimates the planet's temperature at a searing 3,600 degrees Fahrenheit.

On one level, such "hot Jupiters" are a dime a dozen these days. Because they are massive and close to their host stars, they are the easiest planets to spot with virtually every planet-hunting technique astronomers have used to date.

What sets this discovery apart, however, is that the planet is the first to have been found through a process that in some ways could simplify planet hunting, researchers say. Its effectiveness is limited to big planets orbiting close to their stars, the team reporting the discovery acknowledges.

But it also holds out the hope of finding such planets when the parent stars may be too faint for other, currently used techniques. This opens the possibility of adding many more extra-solar planets to a catalog that now tops 800 of them.

No need to hunt for the wobble a planet's gravity imparts to its star's spectrum. No need to wait for a planet to pass in front of its star, known as a transit.

Instead, the team looked for a combination of three relatively small effects that wax and wane throughout a planet's orbit around a star. This delivers a different signal to a planet-hunting device like NASA's Kepler spacecraft than the eclipsing planet, or transit method, delivers, notes David Latham, an astronomer at the Harvard-Smithsonian Center for Astrophysics and a member of the team discovering the planet.

"The transits last just a short time, just a couple of hours," Dr. Latham writes in an e-mail. But the effects the team tracked "rise and fall continuously through the entire orbital period of the planet, roughly 36 hours, so it’s not hard to distinguish these phenomena."

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.

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