Mercury Rising: MESSENGER Reveals Volcanism, Magnetic Storms and a Complex Exosphere on the Solar System's Smallest Planet
NEW YORK--The prevailing view among astronomers used to be that Mercury, the smallest and innermost planet in the solar system, was a static and unevolving world, baked to infernal temperatures by its proximity to the sun. Mariner 10, the first spacecraft to fly by Mercury, offered some tantalizing evidence of volcanic activity in 1974 and 1975. Now MESSENGER, a NASA spacecraft that has passed by Mercury in the past year and will go into orbit in 2011, has confirmed Mariner 10's observations by imaging young lava plains indicative of recent volcanic activity on the planet. MESSENGER has also detected rapid variations in Mercury's magnetic shield and found a surprising distribution of elemental atoms and ions in its exosphere, the extremely tenuous atmosphere of gases that surrounds the planet. [More] Mercury - Solar System - MESSENGER -...