NASA announces discovery of 'Earth 2.0'

NASA's planet-hunting mission, the Kepler Space Telescope, has just discovered Kepler-452b, a planet that scientists are calling "Earth 2.0."

Scientists said in a press conference Thursday that they believe humans could hypothetically survive on Kepler-452b, though it would be challenging to adjust to its gravity, which is about twice that of Earth's.

But don't start packing your bags quite yet, aspiring space travelers. Kepler-452b is 1,400 light-years away in the constellation Cygnus.

Kepler-452b is the first world to be discovered that is about Earth's size, orbits a star similar to our sun and occupies the habitable zone of that star.

So just how similar is it? NASA plotted out the energy received by the other planets discovered by Kepler in relation to the surface temperature of the sun-like star they orbit. The green area represents inhabitable planets.

Kepler-452b is an exoplanet, an especially small Earth-size world. The first exoplanet was discovered in 1995, but its characteristics are drastically different from Earth. The most significant difference with Kepler-452b is its sun: The stars of the exoplanets discovered before this one were significantly smaller and cooler than Earth.

The similarities don't stop at size and temperature. Kepler-452b has an orbit of 385 days, and the star it orbits is about 6 billion years old, 1.5 billion years older than our sun.

"It's awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star; longer than Earth," said Jon Jenkins, Kepler's data analysis lead. "That's substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet."

Before this discovery, the planet most similar to ours that Kepler had discovered was Kepler-186f, though it does not orbit the same type of star as our sun.

Scientists said they next hope to determine what the atmosphere of Kepler-452b is like and whether there are signs of life.