Among Trillions of Planets, Are We 'Home Alone?' In a galaxy that likely holds trillions of planets, ours is so far the only known life-bearing world. Are we really alone? more Life in the Universe: What are the Odds? We don't know when, or even if, we'll find life beyond Earth, but NASA scientists continue the hunt among the thousands of exoplanets confirmed in the galaxy so far. more What's Out There? The Exoplanet Sky So Far We've confirmed only a few thousand of the galaxy's exoplanets, which probably number in the trillions – and already, the variety is stunning.