MERCURY-DIRECTED CME: On Sept 8th around 2300 UT, the SOHO and STEREO spacecraft detected a significant CME emerging from the farside of the sun. Earth is not in the line of fire, but the planet Mercury is. Analysts at the Goddard Space Weather Lab estimate that the cloud will reach the innermost planet on Sept. 9th at 12:00 UT (plus minus 7 hours). Click to view a movie of their CME model:

NASA’s MESSENGER spacecraft is in orbit around Mercury, so it will have a front row seat for the impact. Researchers are keen to learn how Mercury’s magnetosphere responds to CMEs. In particular, they wonder if CMEs can overpower Mercury’s magnetic field and sputter atoms right off the planet’s surface. Thanks to the Goddard forecast, MESSENGER’s controllers know the CME is coming, and they can prepare to observe the impact.

Interplanetary space weather forecasting is a new thing. It became possible in 2010-2011 when NASA and ESA spacecraft surrounded the sun. Working together, SOHO, the Solar Dynamics Observatory, STEREO-A and STEREO-B now have the entire star under surveillance. CMEs can be tracked no matter where they go, which means space weather isn’t just for Earth anymore.

fr/spaceweather.com