After 35 years of space travel, the twin Voyager planetary probes are nearing the very edge of Earth’s solar system. They will become the first man-made objects to travel between the stars.
Voyager 2 was launched first, on Aug. 20, 1977. Voyager 1 followed on Sept. 5, 1977. This was done because Voyager 2 would travel on a shorter path and would arrive at each planet ahead of Voyager 1.
Each Voyager spacecraft carries a golden record attached to its hull. The record is a 12-inch (30 cm) gold-plated copper disc containing sounds and images of Earth. If the Voyagers are eventually found by alien life forms, a diagram engraved into the record cover explains how to play the record.
As of mid-2012, both Voyager space probes are on the outskirts of our solar system, in a region called the “scattered disc.” Voyager 1 is the most distant human-made object at about 11 billion miles from Earth, twice as far as the dwarf planet Pluto. The Voyagers are expected to soon cross the heliopause, considered the boundary between Earth’s solar system and interstellar space. Both Voyagers continue to radio data back to Earth, and their nuclear batteries, though weakening, continue to provide electrical power.