Astronomers just got their most detailed look yet at supersonic 'bullets' of gas piercing through dense clouds of hydrogen gas in the Orion Nebula. Each bullet [image] is about ten times the size of Pluto's orbit around the Sun and travels through the clouds at up to 250 miles (400 kilometers) per second-or about a thousand times faster than the speed of sound. The bulk of both the bullets and the surrounding gas cloud [image] consists of molecular hydrogen. The tip of each bullet is packed with iron atoms that are heated by friction and glow bright blue in the...