Sept. 21, 2013
Earth could continue to host life for at least another 1.75 billion years, as long as nuclear holocaust, an errant asteroid or some other disaster doesn’t intervene, a new study calculates.
But even without such dramatic doomsday scenarios, astronomical forces will eventually render the planet uninhabitable. Somewhere between 1.75 billion and 3.25 billion years from now, Earth will travel out of the solar system’s habitable zone and into the “hot zone,” new research indicates.
These zones are defined by water. In the habitable zone, a planet (whether in this solar system or an alien one) is just the right distance from its star to have liquid water. Closer to the sun, in the “hot zone,” the Earth’s oceans would evaporate. Of course, conditions for complex life — including humans — would become untenable before the planet entered the hot zone.