Martian weather is a pretty strange thing. For one thing, every three Martian years or so, the red planet has giant, globe-encircling dust storms which kick up so much dust that they can be seen from Earth. It also has gigantic cyclones called dust devils that can extend more than 6 miles (9.6 km) into the sky. Many times taller than the typical tornado here on Earth, these storms sport winds that can whip up to speeds of 70 mph (113 kph).
But get your head around this — Mars had an even weirder weather phenomenon in its distant past. Scientists have discovered evidence our solar system neighbor once had tornadolike winds that raged at 500 mph (805 kph), and rolled across its surface, like an Earth tornado turned on its side.
These ancient sideways tornadoes were discovered by Brown University geologist Peter Schultz, who examined images shot by NASA's Mars Odyssey orbital probe a few years ago. Schultz noticed strange-looking bright streaks that emanated from a few big impact craters. (The streaks were visible only in thermal infrared images taken during the Martian night, which may be why no one gave them much notice before.)
Using a variety of methods that included computer modeling of impacts, Schultz and graduate student Stephanie Quintana developed an explanation for how the streaks were formed. When asteroids struck Mars at high speed, they kicked up tons of vaporized material — partly from the asteroid, and partly from the Martian surface — that formed vapor plumes traveling outward at what on Earth would be supersonic speeds. Those plumes interacted with the Martian atmosphere, and generated powerfully swirling winds.
Schultz and Quintana described their findings in a recently published article for the journal Icarus.