Million kilometers long coronal hole appeared in the sun's northern hemisphere

A vast coronal hole stretching more than a million kilometers across the sun's northern hemisphere is facing Earth. A stream of solar wind flowing from this coronal hole (NOAA CH 575) should reach Earth on July 19-20, 2013 so increased geomagnetic activity levels will be possible under the influence of the high speed coronal hole stream. 


The Earth is still inside the fast speed stream due to the low-latitude coronal hole in the northern hemisphere. At the moment the solar wind speed is about 600 km/s and the interplanetary magnetic field (IMF) is rather stable with the magnitude of about 6 nT, blowing southward.

SDO' AIA combined map shows huge coronal hole at northern hemisphere at 14:27 UTC on July 19, 2013 (Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams)

The combined impact of the CME and the incoming solar wind stream could cause some geomagnetic disturbance around Earth in the days ahead. NOAA forecasters estimate a 65% chance of polar geomagnetic storms on July 19-20, 2013.

Composite imagery showing SDO's AIA 193, combined AIA 304, 211 and 171, combined AIA 094, 335 and 193 and AIA 211 (Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams/TheWatchers)

Coronal holes are places in the sun's upper atmosphere where the magnetic field opens up and allows solar wind to escape. A broad stream of solar wind flowing from this particular coronal hole should reach Earth in the next 24 hours. 

STAR coronal  hole and active region map (Credit: SDO)

Coronal hole and active regions marked on SDO's AIA 304 (15:13 UTC on July 19, 2013) and NOAA/SWPC satellite environment plot, AIA 193 (Credit: SDO/NOAA/SWPC)

The solar activity is at low levels. The prominence eruption on the east solar limb at about 17:59 UT on July 18, 2013 was associated with the CME first seen in the SOHO/LASCO C2 field of view at 18:24 UTC. That CME might be Earth directed.

There are currently 7 numbered sunspots on the visible solar disk. Sunspot 1793 still has beta-gamma magnetic and is capable of producing M-class flares. NOAA/SWPC forecasters estimate 15% chance of M-class solar flare eruption in the next 24 hours. 

Featured image: SDO's AIA 193 on July 19, 2013 (Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams)


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