The science behind NASA’s ‘smiling’ sun picture explained

The dark spots of the sun that made the facial patters are called coronal holes. Image courtesy: @NASASun/Twitter

It was a good day for the sun, so good that it was captured smiling.

The National Aeronautics and Space Administration (NASA) shared an image taken from its satellite that showed black splotches on the sun’s surfaces that appeared as a big smile.

NASA’s Solar Dynamics Observatory (SDO) captured the sun at its prime. The image shows what appears to be two black spots and a curved line which prompted many to compare it with a grin.

The SDO is an agency whose mission is to investigate the science behind solar activity and its impact on space weather. Launched on 11 February 2010, the observatory’s spacecraft is tasked to measure the sun’s interior, atmosphere, magnetic field and energy output.

Many Twitter users equated the latest image with Halloween’s jack-o’-lantern as well.

NASA released the image on 26 October saying, “Today, NASA’s Solar Dynamics Observatory caught the sun ‘smiling.’ 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.”

Let’s take a closer look.

What prompted the sun to smile?

The biggest star of the solar system didn’t smile for no reason.

The dark spots of the sun that made the facial patterns are called coronal holes. The Space Weather Prediction Centre says that these holes appear as irregular black patches on the sun’s surface when the images are captured in ultraviolet light or certain types of X-ray images.

The dark appearance of coronal holes can be attributed to their relatively cooler temperature as compared to surrounding areas as well as their low density. All of these characteristics allow streams of fast solar wind to escape into space more easily.

Coronal holes can pop up on the sun’s surface at any time. Wikimedia Commons

Coronal holes can pop up on the sun’s surface at any time. However, they are more common and persistent around the years of solar minimum – the period that records the least solar activity in the sun’s solar activity.

The most persistent coronal holes can last through several solar rotations. The prevalence of coronal holes is near the solar north and south poles. Persistent coronal holes are long-lasting sources of high-speed solar wind streams that are released into space.

What causes Coronal Holes to form?

According to the Australian Space Weather Forecasting Centre, Coronal Holes occur when the Sun’s magnetic field is open to interplanetary space.

The magnetic field of coronal holes is different from that of the sun. While the big star’s magnetic field returns to its surface, a coronal hole’s magnetic field lines stay open and stretch out into space. It is, however, not clear where they reconnect.

When the position of a coronal hole is near the centre of the Earth-facing solar disk, the hot gases from the hole flow towards Earth at a higher speed than the usual solar wind. This phenomenon might cause geomagnetic disturbances on Earth and on the flip side, it can also create dazzling aurora light shows.

Auroral activity depends on the size and location of a coronal hole on the disk. The bigger the coronal holes, the faster the solar wind speed.

Could the Sun’s smile mean trouble?

The sun’s smile is cute and everything but it’s not good news for earth.

The Earth’s magnetic field acts as a shield to deflect the high-speed solar winds that gush towards it. However, it still has the ability to disturb our planet’s atmosphere.

According to a report by Chron, whenever the electrically-charged particles emitted from the sun strike Earth, chances are that these particles get picked up by radio antennae. This can cause disruptions to radio, television and other communication channel transmissions like GPS. Meanwhile, severe solar storms can also damage electrical girds and cause power outages.

Nobody but SpaceX can serve as a testament to the amount of damage coronal holes caused it. In February 2022, a geomagnetic storm destroyed up to 40 Starlink satellites worth over $50 million, according to Space.com.

Last Saturday, the National Oceanic and Atmospheric Administration’s Space Weather Prediction Centre issued a minor geomagnetic storm watch.

Twitter reacts

Twitter users went gaga over the image of the smiling sun. From the Teletubbies sun to jack-o-lantern, there is no dearth of comparisons made with the latest image.

One user wrote, “It’s just dawned on me that @TeletubbiesHQ were right all this time about there being a face in the sun.”

Another user said, “A sweet face… and indeed let’s return a smile of love for this incredible star that warms our lives, made our world.”

While some users found the picture to be cute, others found it creepy.

With inputs from agencies

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