Welcome to the history books, Voyager 2. NASA launched the probe back in 1977 and all these decades later it's finally stepped out into the space between the stars. It joins Voyager 1, which entered interstellar space in 2012.

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NASA announced on Monday that Voyager 2 has left the heliosphere, an area the agency describes as a "vast bubble around the sun and the planets dominated by solar material and magnetic fields." 

Data shows the probe crossed over on Nov. 5 and is now 11 billion miles (18 billion kilometers) from Earth.

Voyager 2 carries an instrument called the Plasma Science Experiment (PLS) that detects the properties of solar wind. NASA noticed the PLS saw a serious decline in the speed of solar wind particles on Nov. 5. After that, it picked up no solar wind flow, indicating the probe's entry into interstellar space. 

"Our studies start at the sun and extend out to everything the solar wind touches," says Nicola Fox, director of the Heliophysics Division at NASA . "To have the Voyagers sending back information about the edge of the Sun's influence gives us an unprecedented glimpse of truly uncharted territory."  

Voyager 2 launched a couple weeks before Voyager 1, and both have long outlived their original five-year missions to study Jupiter and Saturn. NASA scientists are now excited to learn what the probes can teach us about the realm beyond the heliosphere boundary.

Besides passing the interstellar milestone, Voyager 2 is also NASA's longest running mission. The space agency hopes it will be able to collect data from the spacecraft until at least 2025.