The Sun as seen by the Solar Dynamics Observatory. Credit: NASA/LMSAL.

The Sun has been acting kind of weird for close to five years now. The good news is that it’s been oddly quiet. The less good news is that we don’t really know why.

The Sun undergoes an 11-year magnetic cycle. In the Solar Minimum, it’s very calm, with few or even no sunspots, and very little other activity. It just shines. Over time, though its magnetic field gets tangled up, and it starts to get cranky. First, there are sunspots, and then all manner of other phenomena: solar flares, solar prominences, and the ominous coronal mass ejections, or CMEs. This is called the Solar Maximum. After a while of this, the whole magnetic field flips over, and things quiet down again.

It’s those CMEs you have to worry about. CMEs are giant clouds of protons that are blasted into space at high speeds. If they head toward Earth, they get funneled toward the poles by our own magnetic field, where they create the auroras. But if they get too big, the results could be catastrophic.

But there is some good news. Check out this graph of sunspot numbers since 2000:

High numbers mean a lot of Solar activity, and a high risk of big solar storms. In 2000-2002, we had a big, double-peaked Solar Maximum, and then, a few years later, things started to get weird. The Solar Minimum of 2008-2010 lasted a year longer than expected. Now, the new Solar Maximum is only half as strong as the last one–much weaker than the predictions.

Why is this happening? We don’t really know, but it’s good for us because it gives us more time to harder our power grid against disruption. And it looks like it’s half over already…but we’re not out of the woods yet. The biggest solar storms in recent memory were the Halloween Storms of 2003, which came long after the Solar Maximum and at a time when the Sun was about as active as it is now.

So here’s hoping the Sun keeps playing nice until at least the next Solar cycle.