The Sun Is Turning Blank And We’re Not Quite Sure Why

A close-up view of the Sun, as seen by NASA's Solar Dynamics Observatory today. NASA/SDO/HMI

Every 11 years, the Sun goes through a solar cycle, where it goes from a period of most activity to least activity – solar maximum and minimum.

At the moment, the Sun is heading towards its solar minimum as part of solar cycle 24 (the first cycle was recorded in 1755). During this period, it’ll start producing less sunspots, magnetically twisted cooler regions that appear now and again. But it’s dropping faster in activity than we thought it would.

“Current solar cycle 24 is declining more quickly than forecast,” NOAA’s Space Weather Prediction Center (SWPC) said. We should have seen about 15 sunspots or so from April to May this year but, well, we’ve seen almost none at all.

“Will solar minimum be longer than usual or might solar cycle 25 begin earlier?” NOAA noted. “Leading solar and space science experts will convene a meeting in the coming years and attempt to predict solar cycle 25.”

According to spaceweather.com, the Sun has actually been blank about 60 percent of the time in 2018. While not too surprising we can’t see many sunspots, it is a bit strange it’s happened so quickly.

“The fact that sunspots are vanishing comes as no surprise,” they said. “The surprise is how fast.”

This chart shows how the drop in sunspots is greater than predicted. NOAA/SWPC

This isn’t the first time recently we’ve seen the Sun with no sunspots. As far back as 2016, as we were on our way to solar minimum, a “blank” image of the Sun showed the surface with no features on it.

From that, we had expected the next solar minimum to be around 2020. At its lowest point, we should see a spotless Sun for up to months at a time. Aside from this we won’t notice too many effects, although a weaker Sun does mean we’re subject to more cosmic rays.

The latest data may suggest solar minimum is arriving earlier than we thought. It may also suggest that this cycle has been particularly weak and the Sun is going through somewhat of a quiet phase, something backed up by the previous solar maximum also being a bit of a dud. That solar maximum, which peaked around April 2014, was the weakest cycle in more than a century since solar cycle 14 in 1906.

We do know the Sun goes through variations, so there's nothing to be too worried about. But it is quite unusual, especially as we’re not even really sure what causes solar cycles. Maybe the Sun is just taking some well-deserved time off. After 4.6 billion years, who could blame it?

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