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Move Over Beatles, Here Comes the Sun—Literally


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March 6th Solar Flare

Video Credit: NASA

In the end, the solar storm that sent a chunk of the Sun screaming toward Earth on Tuesday at four million m.p.h. turned out to be much ado about nothing. The cloud arrived earlier Thursday, just as experts at the National Oceanic and Atmospheric administration’s Space Weather Prediction Center said it would (yes, there really is such a thing as space weather). But the havoc it might have wreaked, including disruptions to satellite communications, jamming of GPS and airline-navigation systems, even massive blackouts — all of which can happen when a blob of electrically charged particles slams into Earth’s magnetic field — never did happen.

We’re not out of the woods yet, though. The Sun goes through a boom-and-bust cycle every 11 years. During the bust, sunspots (which are magnetic storms in the Sun’s upper layers) just about disppear. During the boom, there are lots of them: they routinely throw solar flares and occasionally, as on Tuesday, bits of the Solar atmosphere known as coronal mass ejections. And we’re just entering boom times. “We’re getting the first few snowfalls of the year, so to speak,” said Robert Rutledge, a NOAA space-weather forecaster told the New York Times. In short: there’s more stormy weather ahead.

As far as Earth’s weather is concerned, there’s not likely to be much of an effect (although these blasts from the Sun do tend to light up the skies with spectacular displays of Northern Lights). The Sun does have plenty of effect on our climate, though. Scientists believe that long-term changes in the angle and orbit of the Earth, which cause more or less sunlight to reach the poles over thousands of years, are the trigger (though not the full reason) for the Ice Ages and the warm periods in between that we’ve experienced for many hundreds of thousands of years.

The Sun also brightens and dims slightly over periods of decades: part of the warming the Earth felt in the early 1900’s was due, not to greenhouse gases, but to solar brightening. And the Sun warms and cools during the 11-year sunspot cycle too: warmer when there are lots of spots, like now, cooler when there are fewer. Overall, the Sun hasn’t gotten any since the middle of the last century, so it can’t explain our current episode of global warming.

But wait, we’re not done yet! Yet another theory is based on the fact that when the Sun is active, the Earth’s magnetic field puffs up in response, shielding the planet from interplanetary subatomic bullets known as cosmic rays. When the Sun relaxes, so does Earth’s field. More cosmic rays get through, and this theory says that triggers a cascade of effects that increases cloud cover, reflects sunlight and cools the planet. So if the Sun has been just a bit more active during its boom phase lately — say, over the past 100 years — that activity could have suppressed clouds, explaining global warming without any need to invoke human greenhouse emissions.

Needless to say, climate skeptics love this idea. Unfortunately for them, there’s no evidence of a change in cosmic rays arriving at Earthly detectors over that time, which takes the wind out of their theory.

Bottom line: space weather is going to be unsettled for the next year or two. Communications and power grids could suffer — or not. But none if it is going to affect the long-term upward trend in global temperatures.