Scientists searching for signs of life beyond our solar system should keep an open mind, for planets very different than Earth may well be habitable, a prominent researcher says.

While it may seem natural to zero in on "alien Earths," such a narrow focus would exclude many potentially life-supporting exoplanets, whose diversity continues to astound astronomers, says Sara Seager of MIT.

And researchers can't afford to be so picky, she adds, since they'll be able to get in-depth looks at just a handful of alien worlds for the foreseeable future.