Sunday, January 3, 2016

Undead Sunspot Explodes Again

Credit: NOAA/NASA/ESA/SOHO

Sunspot AR2473, located near the Sun's southwestern limb, the source of the New Year's geomagnetic storm, appears to be in a state of advanced decay. It's not dead yet, though. During the early hours of Jan. 2 it unleashed a strong M2-class solar flare. NASA's Solar Dynamics Observatory (SDO) recorded a tornado of plasma briefly rising up and falling back to the sun's surface. The twister was wider than our entire planet.

This explosion hurled a coronal mass ejection (CME) into space. Almost all of the storm cloud is heading away from Earth. National Oceanic and Atmospheric Administration (NOAA) analysts say the CME could deliver a glancing blow to Earth's magnetic field on Jan. 3 with a chance of G2-class geomagnetic storms, post-impact. High-latitude sky watchers should remain alert for auroras that may be seen as low as New York to Wisconsin to Washington state.

CMEs are huge explosions of magnetic field and plasma from the Sun's corona. When CMEs impact the Earth’s magnetosphere, they are responsible for geomagnetic storms and enhanced aurora.

After the flare, an enhancement was observed in GOES-13 Proton Flux that crossed the NOAA Scale S1 (Minor) threshold, resulting in possible minor impacts on HF radio communications in the polar regions. However, no radio blackouts were observed over the past 24 hours.

NOAA warns that satellite systems may experience significant charging resulting in increased risk to satellite systems. Power grid fluctuations can also occur.

Solar activity is expected to be very low with a chance for C-class flares over the next three days. Solar wind parameters were lately nominal and solar wind speeds were relatively steady between 425-500 km/s.

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