domenica 15 gennaio 2017


SOLAR WIND, INCOMING: A wide hole in the sun's atmosphere is spewing a fan-shaped stream of solar wind toward Earth.  NASA's Solar Dynamics Observatory photographed the canyon-like structure on Jan. 14th:
This is a "coronal hole" (CH)--a region where the sun's magnetic field opens up and allows solar wind to escape.  Material is flowing from this coronal hole at speeds exceeding 600 km/s (1.3 million mph).  The high-speed stream could spark G1-class geomagnetic storms when it arrives on Jan. 18-19.  Arctic sky watchers, mark your calendars! Free: Aurora Alerts

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