Voyager 1 discovers 50,000°C 'firewall' 2 billion km from Earth
NASA's Voyager 1 spacecraft has detected an intensely hot region about 2 billion km from Earth. Dubbed a firewall, it records temperatures up to 50,000°C. The heat in the zone is said to come from energetic particles rather than actual fire. Voyager 1 has been exploring our solar system since 1977.