AP Photo

The first truly Earth-like alien planet is likely to be spotted next year, an epic discovery that would cause humanity to reassess its place in the universe.

While astronomers have found a number of exoplanets over the last few years that share one or two key traits with our own world — such as size or inferred surface temperature — they have yet to bag a bona fide "alien Earth." But that should change in 2013, scientists say.