On August 20, 1977, the U.S. National Aeronautics and Space Administration launched the Voyager space probe from Cape Canaveral, Florida.

FORBES: The Trillion Mile-Per-Gallon Engine

It would be an understatement to say there's been a long build-up to the moment when Voyager 1 ventures into interstellar space: scientists thought the probe was on the edge back in 2010, and we've been waiting for the official milestone ever since.

ENGADGET: AGU study says Voyager 1 has reached interstellar space, but NASA remains skeptical