11:45 AM (Tuesday) | *Solar cycle 25 is underway and the number of sunspots is on the rise*
Paul Dorian
The NASA Solar Dynamics Observatory (SDO) mission consists of one sun observing spacecraft with three instruments which is located in a geosynchronous orbit around Earth. The AIA and HMI instruments provide us with solar imagery of unprecedented detail. This close-up image of sunspot AR 2786 is provided by AIA channel 193 which highlights the outer atmosphere of the sun known as the corona. Hot active regions, solar flares and coronal mass ejections will appear bright and dark areas known as coronal holes are places where very little radiation is emitted. Credit for image, info: NASA/SDO/spaceweatherlive.com, Twitter David I Birch, Jason Guenzel (TheVastReaches).
Overview
After a deep solar minimum, the number of sunspots on our nearest star has been on the increase in recent weeks heralding the new solar cycle #25. The last solar cycle, #24, was one of the weakest in terms of the number of sunspots in more than a century since solar cycle #14 peaked in February 1906 and it continued a downward trend in cycle strength since around 1980 when cycle #21 reached a peak. Many predictions of solar cycle #25 have it just about as weak as its predecessor with a peak likely to arrive sometime in the middle of 2025. Even weak solar cycles, however, can produce significant solar storms and it’s something we’ll monitor closely in coming months.
A full view of the sun from Tuesday, December 1st, features AR 2786 (circled region) and other hot, active regions. Credit NASA/SDO
Details
The number of spotless days on the sun during the latest solar minimum phase peaked last year when there were 281 (77% of the time) and this was the quietest year since 1913 in terms of sunspot numbers. This year has also featured plenty of spotless days on the sun with more than 200 so far; however, sunspot activity has picked up in recent weeks as the new solar cycle #25 gets stronger and stronger. Currently, the sun is speckled with numerous sunspots and a major solar flare actually took place this past Sunday, November 29th, which was the biggest in more than 3 years. The weekend flare did result in a significant coronal mass ejection (CME) into space which will sideswipe the Earth’s magnetic field during the next day or so. In fact, this glancing blow could cause some minor geomagnetic storms with auroras over high-latitude locations such as Canada, Iceland, Norway and Sweden in the next day or two.
Solar cycles have been in a general weakening trend in terms of sunspot numbers since aroudn 1980 when solar cycle #21 reached a peak in intensity. Many predictions for the new solar cycle #25 have it just about as weak as its predecessor, solar cycle #24. Credit NOAA/SWPC
While solar cycle #25 is not expected to be particularly active, there can still be violent eruptions on occasion in the years ahead. Indeed, one of the most significant solar storms on record known as the “Carrington Event” took place during another weak solar cycle, #10, in the year 1859. This particular super solar storm named for the British astronomer who observed it from his private observatory caused a major CME which traveled directly to Earth. The CME reached the Earth some 17.6 hours after the eruption which is much quicker than the normal journey time of 3 or 4 days as an earlier CME actually cleared the way of the ambient solar plasma for the second blast to move so quickly.
Sunspots sketched by Richard Carrington on Sept. 1, 1859. Copyright: Royal Astronomical Society
Rapidly moving fields during the “Carrington Event” of 1859 induced enormous electric currents that surged through telegraph lines and disrupted communications. In fact, telegraph systems all over Europe and North America went haywire and, in some cases, telegraph operators were literally shocked as sparks were flying and telegraph paper was often set on fire. Some systems actually continued to work despite being disconnected from their power supplies as aurora-induced electric currents still allowed messages to be transmitted. Skies all over Earth erupted in red, green and purple auroras - even in tropical locations like Cuba, Jamaica, El Salvador, the Bahamas and Hawaii. The auroras were so bright over the Rocky Mountains that their glow awoke gold miners who began preparing breakfast because they thought it was morning. People in the northeastern US could read a newspaper by the aurora’s light.
Meteorologist Paul Dorian
Perspecta, Inc.
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