Are we alone?
If aliens ever sent us a message, scientists hope to pick it up in a remote part of northern California.
There, in a clearing nestled amid the volcanoes of the Cascade Range, 42 radio dishes point together at the sky. The dishes, each 20 feet across, form a single, giant scientific instrument called the Allen Telescope Array. Scientists built the array to receive radio signals — the sort of message that could answer a very important question: Are we the only intelligent life in this vast universe?