What’s happened is that the sun has “gone blank” for the second time this month. But don’t worry, it’s not about to burn out or anything. “Going blank” is a fancy way of saying that the sun doesn’t have any sunspots on it. It’s perfectly normal — but it does have implications for the future. Including, possibly, the weather over the next several years.
To explain this, we need to get a little technical for a second. The sun goes through phases of solar maximums and minimums, called solar cycles. A single solar cycle usually lasts around eleven years. Right now, we’re seven years into Solar Cycle 24; that is, the 24th solar cycle since 1755, when scientists started recording sunspot activity. The cycle reached its solar maximum back in April 2014, and it’s expected to reach its minimum within the next three or four years. The blank periods like we experienced this month will get longer and longer, going from days to weeks to months.
This is where an R.R. Martin-esque winter comes in. Cycle 24 has been pretty weak overall: the number of sunspots in the maximum phase were some of the lowest since 1755. You can compare this cycle’s weakness with Solar Cycle 14, back in 1906. Remember that year? Yeah, neither do we.
But that’s not the worst of it. Back in 1645 the sun went through a prolonged period of no sunspots — it “went blank” for a really long time. Scientists refer to that period as the “Maunder Minimum.” Non-scientists refer to it as “that time when it was super duper cold in North America and Europe.” Er, the “Little Ice Age.”
It could also be a dangerous period for astronauts. According to Vencore Weather meteorologist Paul Dorian, during solar minimums, the decrease in solar wind and weakening of the sun’s magnetic field makes it easier for cosmic rays to reach the earth — cosmic rays that, when potent enough, can “easily shatter a strand of human DNA.” Yikes.
There’s more, though: the dropping extreme ultraviolet radiation (EUV) from the sun during solar minimums cools and contracts the Earth’s upper atmosphere. Good for satellites, which have an easier time staying in orbit with the reduced aerodynamic drag, bad for astronauts, who can be harmed by the increase in accumulated space junk. We’ve all seen Gravity.
The reduction in sunspots might not mean we need to worry about White Walkers any time soon (thank goodness!), but it is at least something to think about the next time you see a sale on wool sweaters. (And if you’re wondering whether another Little Ice Age would cancel out global warming, the Washington Post answered that three years ago: no. It would only slow it down modestly.)