Yesterday, NASA announced that the Voyager 1 spacecraft has entered interstellar space, meaning it has left our solar system behind and is now heading toward the charmingly named star AC+79 3888. But while we heard about this amazing accomplishment yesterday, the truth is that Voyager 1 has been in interstellar space for a while. Like, an entire year.
That's right, according to NASA, the Voyager 1 spacecraft officially entered interstellar space on August 25, 2012. So why did NASA wait until September 12, 2013 to make the announcement?
It turns out defining the precise boundaries of our solar system isn't as easy as you think. You can't just breeze by Pluto and see a "Now Leaving the Sol System" sign. Many factors help define our solar system and its influence, from plasma densities to magnetic fields. It was only by examining huge amounts of data and comparing them to the various models of our solar system scientists have tweaked over decades that NASA felt confident enough to declare the Voyager was no longer in the neighborhood.
If you want to read a great breakdown about how the scientists came to this conclusion, check out this question and answer session with Ed Stone, one of the project scientists for the Voyager program.
And if you'd like to hear what interstellar space sounds like, NASA has interpreted some of the plasma data they've uncovered as audible signals. So take a quick listen to the sounds between the stars (plasma density remix).
Personally, I find all of this awe-inspiring. Humans have built and launched a device that has traveled beyond our own solar system. The spacecraft serves as an example of the remarkable things we can achieve if we devote our ingenuity and support to them. This is why I'm an optimist -- we're capable of great things if we give ourselves the chance.