Billions of Earth-size planets in Milky Way: Study
LOS ANGELES (AP) - Our Milky Way is home to at least 17 billion planets that are similar in size to Earth, a new estimate suggests. That's more than two Earth-size planets for every person on the globe.
Just how many are located in the sweet spot where water could exist is "simply too early to call," said Mr Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, who presented his work at an astronomy meeting Monday.
It's the first reliable tally of the number of worlds outside the solar system that are the size of Earth, but the hunt for our twin is far from over.
Despite the explosion of exoplanet discoveries in recent years, one find remains elusive: A planet that's not only the right size but also in the so-called Goldilocks zone where it's not too hot or too cold for water to be in liquid form on the surface.