NASA satellite Voyager 1, at 36 years young, is the first man-made object in recorded history to enter interstellar space. Moreover, it's apparently been doing so for around one year -- NASA scientists at the Jet Propulsion Laboratory announced as much this afternoon, and explained how they were tipped off. "We have an instrument on board which can measure the density of ions, the plasma which is out there," Voyager project scientist Ed Stone said in a prepared video. "In March of 2012, it turns out there was a massive eruption from the sun which eventually reached Voyager 1 in April of 2013. When that blastwave reached Voyager 1, it caused the plasma around Voyager to vibrate or oscillate in a certain particular tone. Literally the sounds of interstellar space."
The satellite was originally launched in September 1977 in the interest of studying our own solar system as well as the interstellar medium. Having checked the first of those goals of its list, Voyager 1 is apparently head down on the second one. The satellite was thought to have reached interstellar space some time ago, but now NASA says it's really for sure. We wish it the best of luck exploring the icy void of space between solar systems. Remember to bring a towel!