🛰 🇺🇸 🚀 Voyager finds a 90,000°F "wall of fire" at the edge of our solar system

You would expect the outer edge of our solar system to be freezing cold. Instead, NASA’s Voyager 1 encountered a scorching region of plasma so intense that scientists have called it a “wall of fire.”

When the spacecraft crossed the heliopause, the invisible boundary where the Sun’s solar wind meets interstellar space, it recorded temperatures between 30,000 and 90,000°F (17,000–50,000°C).

This is not actual fire. The extreme heat is created when the outgoing solar wind collides with the thin gas, dust, and magnetic fields of the interstellar medium. As the solar wind slows and compresses at this boundary, its kinetic energy is transformed into thermal energy, superheating the surrounding plasma.

Surprisingly, despite these blistering temperatures, the region would not feel hot to the touch. Temperature measures the average speed of individual particles, but the plasma at the heliopause is incredibly sparse, containing only a handful of particles per cubic centimeter. With so few particles, there is almost no heat energy available to transfer.

Voyager 1 also detected a sharp drop in solar particles and a dramatic rise in high-energy galactic cosmic rays, confirming it had left the protective bubble of the Sun’s heliosphere and entered true interstellar space.

Scientists determined the plasma’s extreme temperature by analyzing tiny waves in the plasma triggered by solar eruptions, then combining those density measurements with theoretical models.

The heliosphere serves as Earth’s first line of defense against dangerous cosmic radiation. Beyond it lies the raw environment of the Milky Way. Today, more than 15 billion miles (24 billion kilometers) from Earth, Voyager 1 continues its historic journey, still sending back valuable data from this distant frontier.

📎 Massimo