2014年7月19日土曜日

SUNSPOT NUMBER DROPS TO ZERO


Solar activity is very low. July 17th brought the first spotless day in nearly three years. The face of the sun was completely blank and the sunspot number dropped to zero. Now, however, two small sunspots are emerging, circled in this image from NASA's Solar Dynamics Observatory:


Neither of these small spots has the kind of complex magnetic field that harbors energy for strong flares. The quiet is therefore expected to continue through the weekend. NOAA forecasters estimate the odds of an M-flare in the next 3 days to be no more than 1%.

Before July 17, 2014, the previous spotless day was August 14, 2011, a gap of nearly 3 years. What happened then provides context for what is happening today.

Overall, 2011 was a year of relatively high solar activity with multiple X-flares; the spotless sun was just a temporary intermission. 2014 will probably be remembered the same way.

As new sunspots emerge and grow, the Solar Max of 2014 will pick up where it left off a couple weeks ago when sunspots were abundant. However, because no one can predict the solar cycle, this "All Quiet Event" is worth monitoring.

Spaceweather
17 July 2014


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