We are not alone by a long shot. Astronomers say that each of the 100 billion stars in the Milky Way probably has at least one companion planet.
With the aid of the Kepler spacecraft, launched in 2009, an international team of 42 scientists has been surveying millions of stars in the Milky Way. They’ve discovered that planets may be as plentiful as grains of sand on a beach, and that many stars likely host planets five times more massive than earth.
We may need to keep searching for E.T., though; none of the planets detected so far appears suitable for “conventional” carbon-based life as known on Earth.