© NASA
A solar flare bursts from the sun.
A solar flare bursts from the sun.
2013 was supposed to be the year of solar maximum -- the peak of an 11-year cycle when the number of sunspots that mar the sun's surface is at its highest.
These sunspots, which are actually cool areas on the sun's surface caused by intense magnetic activity, are the sites of spectacular solar flares and CMEs, or coronal mass ejections, which can send billions of tons of solar material hurtling into space.
But this year, the serious solar fireworks show never materialized.
Sure, we've seen a handful of major solar flares, and a few extra fast CMEs, but scientists say our current solar maximum, known as solar maximum 24, is the weakest one in 100 years.
And some scientists believe that the 25th solar maximum could be even weaker.
To help us understand what's going on here, the American Astronomical Society asked three leading solar scientists to provide an update on the 24th solar maximum at a news conference Thursday.
It turns out there is some controversy in the scientific community about exactly why this year's solar maximum has been so unspectacular.
One theory is that this year's weak solar maximum is part of a 100-year solar cycle.
Graphs going back to the 1700s show that the number of sunspots during solar maximums in the early part of the last three centuries since humanity has been studying the solar cycle is much lower than the number of sunspots during solar maximums in the latter half of those centuries.
When asked what caused the 100-year cycles, the scientists admitted they did not know.
Other scientists are not convinced that this year's weak solar maximum is part of a 100-year cycle, and have not ruled out the possibility that the sun might be on the verge of a Maunder Minimum, a period of time when it exhibits almost no sunspots. The last Maunder Minimum was observed in 1645. However, the last time there was a Maunder Minimum, it was preceded by a relatively strong solar maximum.
Nobody knows exactly what is going on, because we've only been studying the sun for such a tiny sliver of its life, and so much of its behavior is a mystery.
Depeding on the metrics used to quantify Solar Activity, Solar Cycle 24 is weaker than the 100 yr cycle, and even matches the 200 yr cycle (Dalton Minimum).
It is also doing something akin to the Maunder Minimum, which is diving back down at nearly the same slope it came up on.
And, it's doing some things nobody expected:
1.) Shrinking the umbral (darkest areas) of sunspots, which if continued will make it die off even faster (a la the last cycle before the Maunder Minimum).
2.) Failing to converge the North and South Sunspot belts.
It must be borne in mind that the telescopes used to observe in the early days were far inferior to the optics of even the 19th Century. And they did NOT count sunspots until the 1850's. They counted the Sunspot Groups, and Galileo started that.
What will the Sun do next?
Go half dark, as in the time of Justinian?
Go Maunder and give almost no spots for 80 years, save a few half-hearted sputters?
Go Dalton, and give few spots for 40 years?
Go Sporer or Wolfer Minimums, doing who knows what (we have no data on those times)
Go postal, sending out a monster flare to make up for the lack of other output (Svalgaard)?