THE same mechanism that gives comets a faint X-ray glow could be responsible for the recently discovered halo of X-rays around the Red Planet.
NASA's orbiting telescope, the Chandra X-ray observatory, detected X-rays around Mars in 2001. Now, Konrad Dennerl at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany and his colleagues say that heavy ions blowing out from the sun and ploughing into Mars could be responsible.
Dennerl's team simulated the effect of solar particles crashing into the Martian atmosphere. This suggested that the collisions knock out electrons, which then emit X-rays as they cascade down through the atmosphere, matching the halo seen by Chandra (
You could use similar simulations to analyse X-rays around comets, which are also caused by solar particles, says Dennerl. After studying the X-rays, astronomers could then calculate the properties of the solar wind in regions of ...
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