Thanks to the Kepler Space Telescope, NASA has announced the discovery of the first near-Earth size planet in the so-called habitable zone around another star 1,400 light-years from Earth, in the constellation Cygnus — and that star closely resembles our own sun. The exoplanet, Kepler-452b, is the smallest ‘Goldilocks’ planet to date found in a habitable zone, NASA said in a statement.
Normally, for an exoplanet to be in the habitable zone around its star, it needs atmospheric pressure strong enough to support liquid water on the surface. You can figure that out by determining how much energy it receives from its parent star and how far away it is in orbit, and then by comparing that with what life needs to thrive. This time around, not only is the planet in that zone, but it’s a planet-and-sun combination that’s very close to our own.
“On the 20th anniversary year of the discovery that proved other suns host planets, the Kepler exoplanet explorer has discovered a planet and star which most closely resemble the Earth and our Sun,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate at the agency’s headquarters in Washington. “This exciting result brings us one step closer to finding an Earth 2.0.”
Kepler-452b is roughly 60 percent larger in diameter compared with Earth, so that still classifies it as a “super-Earth-size” planet. But it’s still much smaller than a gas giant like Jupiter. Other details: A year on Kepler-452b is 385 days, or just five percent longer than our year, and the parent star Kepler-452 is roughly 6 billion years old, or 1.5 billion years older than our Sun, according to NASA. The star has the same temperature, 20 percent greater brightness, and is slightly larger (10 percent) in diameter.
The team discovered the exoplanet using the transit method. The following video shows how the transit method works: An EKG-like graph measures the brightness of a planet’s parent star, and records how the brightness dips at certain times when the planet is transiting in front of it (video courtesy of NASA Ames Research Center).
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