Are There Other Earths?

What are the odds of life on planets orbiting nearby stars? Scientists, wielding sensitive new telescopes and "big data" tools, have detected planets around thousands of stars; some Sun-like and some very different from our star. Many newly discovered "exoplanets" lie in "habitable zones," where liquid water may support the chemistry that enables biology. How will astronomers discover if we have company in the cosmos...and where they live?