THE NEW YORK TIMES
Two huge sunspots that recently appeared on the surface of the sun are currently causing quite a bit of consternation and interest. The solar storms these sunspots sent toward Earth this week may affect communications and other technologies like GPS and radio signals. They're causing amazing displays of the Northern and Southern Lights. And space weather scientists like us are excited because we wouldn't normally expect this much activity from the sun at the moment.
The sun goes through 11-year cycles of solar activity. What scientists call a solar maximum is the time in the cycle when the sun is putting out the most energy. That's when we tend to see the most sunspots, solar flares and associated solar storms. Some solar maxima are larger or more active than others - such as the 1990-1991 solar max. But this last cycle, which peaked in 2014, was quite small, and there were few large geomagnetic storms.
We're heading into the bottom of solar minimum, when the sun tends to have fewer sunspots, solar flares and coronal mass ejections - large expulsions of plasma, electrons and ions, and magnetic fields. But despite where we are in the sun's cycle, activity on the sun has dramatically picked up over the past few days. On and off, these two sunspots have been flaring and shooting out coronal mass ejections, directed toward Earth.
So what's going on with the sun? And should we be concerned about this somewhat out-of-character solar behavior?
On June 5th, the sun started sputtering. A moderately large flare (classified as an M5.5) erupted at approximately 18:30 UTC. It produced a coronal mass ejection aimed at Earth.
The sun continued to flare on June 6th. A solar energetic particle event from the previous day's activity arrived at the Earth, where it likely affected radio communications as well as the health of satellite systems.
It took about an hour for the solar energetic particles the sunspots emitted to arrive at Earth. These protons are incredibly fast-moving. They can affect communication systems, typically in the polar regions where they are more likely to enter into the Earth's atmosphere. As with all increases of radiation in space, they can also affect satellite systems and the health of astronauts.
Because of the way its magnetic field aligned with Earth's, these recent flares generated only a small geomagnetic storm.
We don't need to worry about this coronal mass ejection being "the big one" - a solar storm direct hit that could cause widespread power blackouts and trigger as much as US$2 trillion worth of damage, according to a National Academy of Sciences study. But this storm, on the back of this month's abnormally active space weather, may wind up on the larger end of the scale, and will be the subject of lots of analysis and research.
Based on observations of this irregular pattern we may see a third coronal mass ejection sometime this month that could have unprecedented effects on radio and satellite communication.
We don't yet fully understand everything that is happening. But the activity over the past few days, when the sun should be within its quietest period, shows that significant space weather events are possible at any stage of the 11-year solar cycle.