The year Voyager 2 was launched, Jimmy Carter was the U.S. President, Red Square was still red, and an obscure band named The Clash released their first album on the now-defunct CBS label.

After an August launch, the second of the Voyager probes conducted a highly successful grand tour of the outer solar system, snapping images of Saturn and giving humanity its very first up-close look at Neptune and Uranus. And then it was the void.

The two Voyager probes still phone home, three decades after their launch. Moving along at the brisk pace of ten miles per second, Voyager 1 punched through what scientists call the termination shock in 2004. That’s the zone where solar wind abruptly slows down as it begins to collide with the interstellar magnetic field: the solar system’s city limits sign. Voyager 2 is on a somewhat different trajectory, just reaching the termination shock last August.

In doing so, Voyager 2 confirmed what scientists have long thought. The solar system isn’t perfectly spherical — it’s bent.

Our sun’s influence extend outward forever. It’s surrounded by a diffuse plasma bubble of its own creation. Beyond that is the gas and magnetic field of interstellar space. Scientists think this weak flow distorts the sun’s bubble. It’s a bit like the bow wave which precedes a ship moving through the water.

If Voyager 2 and its sister manage to stay alive another decade or so, they may be able to report their final crossing of the heliopause. Voyager 2’s systems should begin failing in the next five years as it runs out of electrical power. By 2020, both Voyagers will be tumbling silently in the expanse of interstellar space. They’ll keep going until they run into something. But it’s a big universe, and the voyage is just beginning.

Link: NASA’s Voyager page