Earth’s Twin Discovered!

Since the explosion of exoplanet science in the late 1990s, our entire understanding of the universe beyond our own solar system has changed.  We have confirmed over 1,000 planets orbiting other stars, with another 3500 waiting to be confirmed by subsequent observations.  As we search, our prime directive has always been to improve our technology to determine if other Earths exist, and to seek them out.  Every year we have added another discovery that brings us closer to finding a twin of the planet Earth in space.  Today we have come one step closer, and it is indeed a big step.

Earth and Kepler 452b shown in relative sizes in this artists conception. Credit: NASA

In a press conference, NASA announced the confirmed discovery of Kepler 452b, a planet orbiting a star 1400 light years away in the constellation Cygnus.  This planet is the twelfth discovered that orbits within the habitable zone of its parent star.  But the two real pieces of news that are the most mind blowing are that the planet’s parent star is the same as our Sun, and Kepler 452b orbits at a distance similar to the Earth, giving it a year that is 385 days long!

The star, Kepler 452, is the first G class star (same class as our Sun) ever found to have a habitable zone planet.  The star is a little bit bigger, brighter, and older than the Sun, and even though the planet 452b is orbiting a little bit further away than the Earth orbits, the planet receives 10% more sunlight.  This is not a huge difference, and if we could take terrestrial plants to Kepler 452b, they would photosynthesize and survive!

The planet is about 60% bigger than the Earth.  We don’t know what it’s made of, but if it is rocky, it would be about 5 times as heavy, and it would have twice the gravity.  So a 150 lb person on Earth would have to haul around 300lbs of weight! This would be difficult but not impossible for humans, and we would get very strong over the first few weeks.

The planet marks the latest data release for Kepler, bringing the catalogue of planets to 4696 total candidates and over 1000 confirmed. Only 12 planets have been found in the habitable zone of their parent star, and 11 of them have been found orbiting stars smaller and dimmer than the Sun.

New Kepler planets in yellow show a lot more Earth-sized discoveries. Credit: NASA

Most of the new Kepler discoveries are Earth-sized planets or ‘Super-Earths,’ meaning we will find more and more potential habitable zone planets soon!  The habitable zone of the star is the range of orbital distances where the energy received from the star is just right for a planet to host potential liquid water, a necessity for life as we know it.  Exoplanet science is hot, and it’s only going to get hotter!

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