Did Voyager 1 Leave the Solar System or Not?
The thing about crossing into uncharted territory is that you may not know when, exactly, you have crossed into it. No one needs to tell that to the Voyager 1 spacecraft, which is currently at the center of a controversy about where the solar system ends and interstellar space begins.
Today, a press release from the American Geophysical Union initially stated Voyager had left our solar system. Two hours later, though, they issued a correction calling Voyager’s current location a “new region of space,” which is considerably less flashy (but equally scientifically valuable). The NASA Jet Propulsion Laboratory, which oversees the spacecraft, weighed in with a press release saying that no, in fact Voyager was still in the solar system.
So why the controversy? What is the debate about the boundary of the solar system? And what is this “new region” of which the scientists speak?
Let’s begin at the beginning. NASA launched Voyager 1 in 1977. Since then, the 1,600-pound (722 kilogram) probe has been zipping away from Earth and toward the edge of the solar system. It is currently more than 11 billion miles from the Sun, which is nearly three times as far out as Pluto is (don’t worry, Pluto; Voyager isn’t a planet, either).
But moving 11 billion miles from home isn’t always enough to free you of its influence. In the case of the solar system, the region where the Sun’s influence dominates is known as the heliosphere. Here, the Sun has blown high-speed, charged pieces of itself into a womb-like bubble.
Since 2004, Voyager 1 has been traveling in a subsection of the outer heliosphere: the heliosheath, where the solar wind slows down in response to pressure from the interstellar medium, which is the combination of winds from other, distant stars. When the influence of the solar wind and the interstellar medium are equal, the solar system ends, or so we say, and actual interstellar space begins. But determining whether or not Voyager has arrived there is no simple task.
Read the full article at: discovermagazine.com