Solar Flares & Solar Wind

CHANCE OF FLARES: Sunspot 1302, quiet now for three days, still has a ‘beta-gamma-delta’ magnetic field that harbors energy for X-class flares. NOAA forecasters estimate a 30% chance of such eruptions today. X-flare alerts: text,voice.

SOLAR WIND BLASTS MERCURY: At a NASA teleconference yesterday, researchers working with data from the Messenger spacecraft offered new evidence that gusts of solar wind are penetrating Mercury’s magnetic field and eroding material off the planet’s surface. The spacecraft has actually flown through plumes of ionized sodium scoured from the surface and escaping from weak points in Mercury’s magnetosphere. Click here and scroll down to “Presenter #4” for relevant data and images.

Another “scouring event” could be in the offing. The Solar and Heliospheric Observatory (SOHO) observed two farside CMEs on Sept 29th, and one of them is heading for the innermost planet:

Using observations from SOHO and the twin STEREO spacecraft, analysts at the Goddard Space Weather Lab have modeled the trajectory of these CMEs. The one on the left should hit Mercury on October 1st at 02:13 UT +/- 7 hours. Forewarned, mission scientists for the Messenger probe can be attentive to the CME’s arrival and observe its effects on Mercury.

According to the CME’s forecast track, the cloud will hit Venus later the same day. The ability to forecast CME impacts on other planets is a new development in space weather forecasting made possible by NASA’s deployment of spacecraft around the full circumference of the sun.


Four New CME’s

FOUR CMEs: On Sept. 19th, the STEREO-SOHO fleet of spacecraft surrounding the sun detected six coronal mass ejections (CMEs). Two of the clouds rapidly dissipated. The remaining four, however, are still intact and billowing through the inner solar system. Click to view a movie of their forecasted paths:

According to analysts at the Goddard Space Weather Lab, who prepared the movie, one CME should hit Mercury on Sept. 20th at 05:40 UT while another delivers a glancing blow to Earth’s magnetic field on Sept. 22th at 23:00 UT. All impact times have an uncertainty of plus or minus 7 hrs.


Mercury Receiving CME

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.