Monday, October 26, 2015

Long Filament Seen on a Very Quiet Sun

Image credit: NASA/SDO

This past week the sun featured a long dark line, known as a filament, which stretched at least halfway across its face as seen in the top half of this image from NASA's Solar Dynamics Observatory, captured on Oct. 21, 2015. This filament is about the length of 50 Earths side-by-side. Filaments are elongated clouds of solar material that are tethered above the sun by magnetic forces.

They are often unstable and usually break apart in less than a week, though they can last longer than that. Filaments are darker than most of the sun’s surface when viewed in extreme ultraviolet light. This filament was imaged in extreme ultraviolet wavelengths of 193 angstroms, which is normally invisible to our eyes but is colorized here in bronze.

Solar activity is very low, and it is likely to remain so for the next days. National Oceanic and Atmospheric Administration (NOAA) forecasters say there is only a 20 percent chance of M-flares and no more than a 1 percent chance of X-flares on Oct. 26.

Auroras may be visible in the coming days at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Geomagnetic field activity ranged from quiet to active levels. Quiet levels were observed on Oct. 19 and quiet to unsettled levels were observed on Oct. 22-25 under nominal solar wind conditions. The activity is expected to reach G2 (Moderate) geomagnetic storm levels on Nov. 3-4 with G1 (Minor) storm levels expected on Nov. 5, 08-10, and 14.

Solar activity is expected to be at low levels in November.


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