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| AI Generated: NASA's Voyager Found a 50,000 Kelvin Plasma Wall |
When NASA launched the Voyager probes in 1977, no one knew exactly what lay beyond the planets. Decades later, as the spacecraft reached the boundary of our Solar System, they found something extraordinary — a searing-hot “wall” of plasma where temperatures soar to 30,000–50,000 kelvin (about 54,000–90,000°F).
That boundary is called the heliopause — the invisible frontier where the Sun’s magnetic field and solar wind meet the interstellar medium. Inside it, the Sun dominates space; beyond it, the Milky Way takes over.
“The Sun sends out a constant flow of charged particles called the solar wind,” NASA explains. “This forms a giant bubble around the Sun and its planets, known as the heliosphere.”
Voyager 1 crossed this frontier on August 25, 2012, becoming the first spacecraft to leave the heliosphere. Voyager 2 followed in 2018, confirming that the “edge” of our Solar System isn’t fixed — it breathes, expanding and contracting with the Sun’s activity.
Despite the intense heat recorded, the Voyagers survived. The region is so sparse that the superheated particles rarely collide with the spacecraft — meaning the heat can’t actually transfer to them.
The discovery revealed something even stranger: the magnetic fields inside and outside the heliosphere are aligned, suggesting the Sun’s influence extends farther than expected.
Nearly 50 years after launch, both Voyagers are still transmitting data from interstellar space — humanity’s longest-running and farthest-reaching mission.
Source: “NASA’s Voyager Spacecraft Found a 30,000–50,000 Kelvin ‘Wall’ at the Edge of Our Solar System,” IFLScience, 31 October 2025.