Launched over 40 years ago, NASA’s Voyager 1 and 2 spacecraft are still cruising through space, pushing the boundaries of human knowledge Among their most recent revelations is a bizarre and fiery-sounding region nicknamed the “firewall,” a place filled with supercharged particles at the very edge of our solar system.
In 1977, when Walkmans ruled the music scene and the internet was barely a concept, NASA sent Voyager 1 and Voyager 2 on a bold mission: explore the solar system and beyond. Equipped with instruments and a golden record (a time capsule of Earth’s sights and sounds), their goal wasn’t just planetary flybys, but also to go where no spacecraft had gone before.
“Where’s the limit?” That question became the fuel behind this decades-long journey.
A common debate among astronomers and space enthusiasts is: Where does our solar system really stop?
Some say it ends after Neptune, while others argue it stretches to the distant Oort Cloud, a zone filled with icy objects and “sleeping” comets. But NASA has a more scientific marker: the heliopause.
Imagine the Sun blowing a giant bubble around itself that’s the heliosphere, filled with solar winds and charged particles. The heliopause is the edge of this bubble, the point where solar winds weaken and interstellar space begins.
Once the Voyager probes crossed the heliopause, they didn’t just find silence and stillness. Instead, they encountered a region with astonishingly high temperatures, between 54,000 and 90,000 degrees Fahrenheit (roughly 30,000–50,000°C). Scientists dubbed it the “firewall.”
But here’s the twist: this isn’t fire like we know it. The area is packed with super-energetic, sparse particles. Because the particles are so spread out, they don’t burn the spacecraft, but they carry immense energy enough to shock scientists.
And no, Voyager 1 and 2 didn’t melt. The vacuum of space and the thinness of this energetic region spared them from combustion.