Astronomers have been discovering planets outside our solar system since 1995, but they’ve never found and confirmed any with Earth-like, life-supporting characteristics. According to some experts, that’s set to change in 2013.

NASA’s Kepler Space Telescope has been doing much of the planetary legwork. Since it launched in 2009, the Kepler has spotted more than 2,300 potential planets, including nine orbiting in their respective suns’ “habitable zones” –areas where liquid water can exist. One such planet, known as Kepler-22b, is 2.4 times the size of Earth.

Several experts believe they telescope will be able to confirm and Earth-like planet’s existence next year–including Planetary Habitability Laboratory head Abel Mendez, who says he’s “very positive” an Earth twin will be discovered, and Kepler team member Geoff Marcy, who thinks a 2013 confirmation is “likely.”

According to veteran astronomer Mikko Tuomi, the first discovery isn’t likely to be the last. “Estimating carefully, there are 200 billion stars that host at least 50 billion planets, if not more,” in the Milky Way alone, he told “Assuming that 1:10,000 are similar to the Earth would give us 5,000,000 such planets,” he added, “so I would say we are talking about at least thousands of such planets.

Marcy speaks in poetic terms when describing what such a discovery would mean for humanity. “The small steps for humanity will be a giant leap for our species. Sending robotic probes to the nearest stars will constitute the greatest adventure we Homo sapiens have ever attempted,” he said. “This massive undertaking will require the cooperation and contribution from all major nations around world. In so doing, we will take our first tentative steps into the cosmic ocean and enhance our shared sense of purpose on this terrestrial shore.”

(Image: Bluedharma/Flickr)