Astronomers have discovered for the first time a distant planet that is perilously close to its aging star, according to a study released Monday, the results of which give insight into the possible end of planet Earth. Located 2,600 light-years from Earth, Kepler-1658b is a Jupiter-sized exoplanet.
But unlike this gas giant farthest from the sun, Kepler orbits only its star, one-eighth the distance that separates our sun from Mercury, the closest planet.
The study, published in The Astrophysical Journal Letters, indicated that this “hot buyer” orbits its star in less than three days, and this rotation period is shrinking by about 131 milliseconds per year.
“At this rate, the planet will collide with its star in less than three million years,” said lead author Shreyas Visapragada of the Harvard-Smithsonian Center for Astrophysics.
“This is the first time we’ve seen direct evidence of a moving planet, spiraling around its aging star,” the astrophysicist told AFP. The star in question is late in its cycle, when it begins to swell and get brighter.
Kepler’s orbit shrinks inexorably under the influence of the star’s gravity, similar to the Moon’s gravity on various points on the Earth. This effect called tidal force can attract two bodies just as it can pull them away from each other, for example the moon is very slowly moving away from the earth in a spiral pattern.
Earth’s Last Goodbye?
Will our planet experience the same process of disintegration? “The death of a planet from a star is a fate that awaits many worlds: It could mean the final farewell of the Earth after billions of years as it continues to orbit the sun,” the Center for Astrophysics wrote in a statement. In five billion years, the sun will become a “red giant” that will grow exponentially, similar to Kepler’s host star.
Like this exoplanet, the Earth can inexorably approach the sun under the influence of tidal forces. But this effect may also be offset by the sun’s mass loss, says Shreyas Visapragadhan, who points out that “Earth’s ultimate fate is not yet clear.”
Kepler was the first exoplanet to be detected by the Kepler space telescope, in 2009. For 13 years, scientists have observed the slow but steady change in the planet’s orbit as it passes in front of its host star.
Finding it surprisingly bright compared to other exoplanets, they had long speculated that it reflected starlight particularly well. But they now believe Kepler is hotter than expected due to the star’s gravitational pull.
