Einstein provides a blueprint for discovering planets.
Einstein’s relativity theory is having a great year. Less than a month after Max Planck Institute researchers observed a neutron star and white dwarf star orbiting each other and exhibiting gravitational interactions that matched the theory of relativity exactly, another international team of astronomers credited Einstein’s theory with enabling them to locate another planet in another star system.
They’ve dubbed the planet in question Kepler-76b, and it’s a Jupiter-like gas giant, some 25 percent larger than Jupiter and with double the planet’s mass. Its star is in the constellation Cygnus and is about 2,000 light-years from Earth.
The researchers, based out of Tel Aviv University and the Harvard Smithsonian Center for Astrophysics, had been observing a star system through the orbital Kepler telescope and were using as their guide the theory of relativity’s predictions for gravity’s effect on light. This discovery brings to a successful conclusion two years that Tsevi Mazeh, Tel Aviv University astronomer, had spent putting the theory to the test in search of new planets.
The Tel Aviv and Harvard researchers were together looking for three specific effects, all of them very subtle: the star’s light alternately brightening and dimming as the planet’s gravity tugs on it while the planet is moving toward the observer and then moving further away; the star’s shape seeming to us to distort into a football-like figure, a result of gravitational tides; and starlight being reflected by the planet.
The researchers were hoping that, if a planet was there, and if Einstein’s theory was on-target, then they’d be able to spot these gravitational effects at work as the planet orbits the star. They were not disappointed. The astronomers published their findings in the most recent edition of the Astrophysics Journal.
Two researchers—Avi Leob of Tel Aviv University and Scott Gaudi, who now teaches at Ohio State University—had outlined this detection method back in 2003. But this recent planet discovery is the first real-life success that astronomers can attribute to it.
This recent success is all the more significant not only because it further bolsters Einstein’s genius, but also because it offers astronomers a credible means to detect new exoplanets—including, perhaps, Earth-like planets—without having to actually see them but instead just seeing some very slight alterations that they make to a star’s outgoing light waves. This matters since today’s telescopes are not high-capacity enough to capture actual views of planets that are comparable to Earth in size—which most terrestrial planets would be.
The finding comes as astronomers around the world continue to dig through data collected by NASA’s Kepler Space Telescope. The telescope, which has discovered just under 3,000 planets to date, is slated for retirement later this decade, when the space agency plans to launch the James Webb Space Telescope.