In 1977, NASA launched the twin Voyager spacecraft to traverse the far reaches of the solar system and beyond. Voyager 2 left on August 20, followed by Voyager 1 on September 5.
These remote ambassadors still beam messages back to Earth 40 years later, with data from their deep space travels. Voyager 1 is about 13 billion miles from Earth, in interstellar space, and Voyager 2 is not far behind.
Find out more about the Voyager mission at NASA.