Humans have been broadcasting radio and television signals into deep space for about a hundred years. And if anyone is listening, they might send something back. Dan Werthimer directs the University of California, Berkeley’s search for extraterrestrial intelligence, or SETI, and he says that our broadcasts have already gone past thousands of stars.

"The early radio shows and early television have gone past 10,000 stars. The nearby stars have seen the "Simpsons" and the distant stars have seen "I Love Lucy," and "Ed Sullivan." So we're sending off all of this radio and television, and radar, and maybe E.T. does something like that, or if we're very lucky, maybe they send us a deliberate signal."

Werthimer says that unlike radio and television signals, laser signals are for point-to-point communication, and receiving one could mean that E.T. knows where we are. His team has recently started looking for these signals in infrared.

"These are colors that you and I can’t see, but they’re very good for interstellar communication and we’re hoping E.T. might send us a laser signal."