Solar watch: A tale of 4 coronal mass ejections

September 20, 2011 – 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. 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. –Space Weather

       

New findings on flares: NASA’s Solar Dynamics Observatory (SDO), launched in February 2010, made the finding:  About 1 in 7 flares experience an “aftershock.” About ninety minutes after the flare dies down, it springs to life again, producing an extra surge of extreme ultraviolet radiation. “We call it the ‘late phase flare,’” says Woods. “The energy in the late phase can exceed the energy of the primary flare by as much as a factor of four.” What causes the late phase? Solar flares happen when the magnetic fields of sunspots erupt—a process called “magnetic reconnection.” The late phase is thought to result when some of the sunspot’s magnetic loops re-form. A diagram prepared by team member Rachel Hock of the University of Colorado shows how it works. The extra energy from the late phase can have a big effect on Earth. Extreme ultraviolet wavelengths are particularly good at heating and ionizing Earth’s upper atmosphere. When our planet’s atmosphere is heated by extreme UV radiation, it puffs up, accelerating the decay of low-orbiting satellites. Furthermore, the ionizing action of extreme UV can bend radio signals and disrupt the normal operation of GPS. -NASA   

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