Recap: Voyager 2 launched 16 days before Voyager 1 on August 20, 1977. Initially commissioned as a five-year mission to study Jupiter and Saturn, it eventually conducted flybys of Uranus and Neptune and is still providing useful data more than 41 years later.

NASA’s Voyager 2 probe has become only the second human-made object to reach interstellar space, the agency said over the weekend.

The milestone actually took place on November 5 when Voyager crossed the outer edge of the heliosphere, the protective bubble of particles and magnetic fields created by the Sun. The probe’s twin, the Voyager 1, was the first to reach interstellar space in 2012 although Voyager 2 is far more interesting as it still has working instruments.

NASA used data from these instruments, namely the Plasma Science Experiment (PLS), the cosmic ray subsystem, the low energy charged particle instrument and the magnetometer, to conclude that Voyager had indeed crossed the outer bound of the heliosphere called the heliopause.

Data from Voyager 2 is beamed back to Earth at the speed of light. At more than 11 billion miles from home, it takes about 16.5 hours for information to travel through our solar system. By comparison, it takes light just eight minutes to reach Earth from the Sun.

Neither probe has left our solar system, however, and won't be doing so anytime soon. NASA estimates that it'll take another 300 years for Voyager 2 to reach the inner edge of the Oort Cloud (the boundary of the solar system) and perhaps another 30,000 years to fly beyond it.