NASA Voyager 2 Probe Enters Interstellar Space 11 Billion Miles From Earth

In October, NASA revealed that its Voyager 2 probe, which was launched in 1977, had started to detect an increase in cosmic rays from beyond our Solar System. The space agency said the change hinted at the possibility of nearing interstellar space, something it has now confirmed a little over a month later. The Voyager 2's arrival in interstellar space comes a handful of years after Voyager 1's own similar achievement.

The Voyager 2's milestone marks the second time a human-made object has entered interstellar space. The achievement involved exiting the heliosphere, as the image above shows, something Voyager 1 did back in 2012. NASA says the Voyager 2 is a little over 11 billion miles from our own planet, though its mission operators are still able to communicate with the probe.

At this distance, it takes around 16.5 hours for information from the probe to reach Earth, though, making it a tedious process. NASA's Voyager team used data from the spacecraft's instruments to determine that it left the heliosphere back on November 5.

Voyager 1's Plasma Science Experiment instrument stopped working in 1980, but Voyager 2's instrument is still working and provides unprecedented observations of the passage into interstellar space. It was this instrument that observed a "steep decline" in solar wind particle speeds on November 5, this being "the most compelling evidence" of entering interstellar space, according to NASA.

Zero solar wind flow has been observed with the instrument following November 5, underscoring Voyager 2's milestone. Other instruments on the spacecraft have provided evidence consistent with having crossed past the heliopause and into interstellar space. Over time, scientists will study this data to better understand Voyager 2's environment.

The unprecedented space achievement precedes the upcoming Interstellar Mapping and Acceleration Probe (IMAP) mission scheduled for 2024.