THE Mars Express spacecraft has seen a light show on the Red Planet similar to the auroras on Earth.
The Earth's auroras are caused by charged particles from the solar wind pouring down the planet's magnetic field lines and hitting molecules of gas in the atmosphere, causing the molecules to glow. The Earth's magnetic field radiates out of its poles, and so auroras appear around the poles. But Mars has no intrinsic magnetic field. Instead, as Jean-Loup Bertaux from the National Centre for Scientific Research in Verrières-le-Buisson, France, and his team found, the solar particles flowed towards an area of highly magnetised rock, creating beams of light, rather than diffuse Earth-like auroras (Nature, vol 435, p 790).
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