NASA’s ‘Smiling Sun’ Image Is a Reminder of the Threat of Solar Wind

Coronal holes on the sun can release jets of charged particles that may interfere with Earth’s atmosphere

The dark patches on the image of the sun captured by  NASA’s Solar Dynamics Observatory are trio of coronal holes.  NASA/GSFC/SDO

In a NASA photo that made the rounds on social media last week, the sun appeared to smile for the camera.

The image, taken by the space agency’s Solar Dynamics Observatory satellite, was shared on one of NASA’s Twitter accounts. Social media users have compared the happy face pattern to a Halloween jack-o’-lantern, a lion and even the baby-faced sun from the children’s show Teletubbies, reports The Guardian’s Maya Yang.

Of course, it’s not really an image of the sun saying cheese: “Seen in ultraviolet light, these dark patches on the sun are known as coronal holes and are regions where fast solar wind gushes out into space,” NASA wrote in the tweet.

The coronal holes are cooler and less dense relative to the plasma that surrounds them. “Because they’re so dark and because we’re looking at it in ultraviolet radiation, which the naked eye can’t see, the [NASA satellite] sees them as dark holes,” Brian Keating, an astrophysicist at the University of California at San Diego, tells the Washington Post’s María Luisa Paúl.

But despite their friendly appearance, the coronal holes are a bit foreboding, as this sort of solar activity has the potential to affect telecommunications and other crucial services on Earth.

Coronal holes can develop anywhere on the sun at any time, but they are more common during solar minimums, or periods of lower activity during the sun’s 11-year cycle.

Those dark regions have open, unipolar magnetic fields that allow solar wind—a continuous flow of protons, electrons and other charged particles from the sun—to escape more easily into space. These rapid streams of particles are powerful enough to reach Earth, but our planet’s magnetic field acts as a shield to deflect much of the solar wind activity.

NASA ScienceCasts: Effects of the Solar Wind

Still, these events can disrupt our atmosphere, reports CNN’s Jackie Wattles. The wind can result in geomagnetic storms, or rapid decreases in the strength of Earth’s magnetic field. These storms range from minor G1 events to extreme G5’s, which can “disrupt power and other systems on Earth while also impacting spacecraft operations,” writes Li Cohen for CBS News. Such drops in the strength of the Earth’s magnetic field last about 6 to 12 hours, and after, the field gradually recovers over the course of a couple days, according to NASA.

As a result of the sun “smiling,” NOAA’s Space Weather Prediction Center issued a minor geomagnetic storm watch, warning that the coronal holes were “anticipated to enhance and disturb the solar wind environment and lead to unsettled conditions, with a chance for active levels and slight chance of G1 storms.”

These solar-induced events have the power to “cause anomalies and disruptions to the modern conveniences we have come to rely on,” such as telecommunications and GPS, according to the National Weather Service.

Keating tells the Post that severe geomagnetic storms can also cause power outages by damaging the electrical grid. The last of these to heavily impact Earth was the 1859 Carrington Event, which sparked fires at multiple telegraph stations—and something similar is likely to happen again, he tells the publication.

“Scientists expect that to happen on average, with a couple percent probability, every year, and we’ve just dodged all these magnetic bullets for so long,” Keating tells the Post. “[A similar event now] could be really scary, and the consequences could be much more dramatic, especially in our technology-dependent current society.”

On the bright side, these storms’ disturbances to Earth’s magnetic field result in increased visibility of the northern lights in more southern areas, to the point that auroras could appear in Florida and Texas in extreme cases, per CBS News. Still, it’s probably for the best that NASA has continued to report no geomagnetic storms on its Twitter.

This isn’t the first time the sun has been captured smiling—in 2013 NASA caught another solar “grin” made from coronal holes, and in 2014, the space agency captured a photo of what it called the “Pumpkin Sun,” in which active regions on the star that emit more light and energy gave it the appearance of a jack-o'-lantern.

NASA’s Solar Dynamics Observatory, a space-based mission launched in 2010, captured these and the current image. By studying space weather, the satellite seeks to better understand the relationships between the sun and Earth.

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