Science News - 13 Apr 2010
The planet's strange atmosphere may have a lot to do with the sun
If you look at pictures of Mercury taken with a high-powered telescope, the planet looks peaceful and calm. It’s tiny, barely bigger than our moon, and covered by craters. But up close, and seen with the right scientific instruments, Mercury sends out a different message. The sun, its nearby neighbor, blasts the tiny planet with radiation. And the planet’s tornadoes are like nothing you’ve ever seen ... because they’re invisible. They form when part of the planet’s magnetic field twists up into a spiral, and they open up a connection between the planet’s surface and outer space. These tornadoes are enormous — sometimes as wide as the planet itself — and can appear and disappear within a few minutes. On Earth, tornadoes form when two weather systems collide. On Mercury, magnetic cyclones show up when powerful forces, called magnetic fields, smash together.
First image of Mercury taken by cameras on board NASA’s MESSENGER mission in January 2008.
MESSENGER has flown by Mercury three times and will start to orbit the planet next year.
(NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)
The aurora borealis, or Northern Lights, often appears as a curtain of fire in the sky. This
spectacular light show has two main players: Earth’s magnetosphere and the solar wind.
(Philippe Moussette/Obs. Mont Cosmos)
Red arrows indicate the direction of fast solar wind streams leaving the sun.
Yellow lines show magnetic fields in the sun’s atmosphere. (ESA/NASA)