The giant sunspot has doubled in size in 24 hours and is aimed at Earth

A giant sunspot that has doubled in size in just 24 hours is now facing Earth – meaning it could send a solar flare our way.

Sunspots are dark areas on the sun’s surface associated with intense bursts of radiation. They appear dark because they are cooler than other parts of the Sun’s surface.

Sunspots are relatively cool because they form over areas where the Sun’s magnetic fields are particularly strong — so strong that they prevent some of the heat within the Sun from reaching its surface.

Sunspot AR3038
Sunspot AR3038, seen at the center of this screenshot of the Sun by images from NASA’s Solar Dynamics Observatory. Sunspots can be a source of solar flares.

These tangled magnetic fields can sometimes suddenly reorganize themselves. When that happens, a sudden burst of light and radiation is ejected from the sun in the form of a solar flare.

The sunspot, which has been increasing in size recently, is known as AR3038. Images from NASA’s Solar Dynamics Observatory on Sunday show how the sunspot has evolved over the past few days or so, twisted and distorted.

“Yesterday sunspot AR3038 was large. Today it’s huge,” according to the website. “The fast-growing sunspot has doubled in size in just 24 hours.”

The magnetic field associated with the sunspot means it could potentially send an M-class solar flare back to Earth — the second most powerful kind. Whether that will be the case, however, is unknown.

As of Monday morning, the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) had issued no solar flare warnings.

If powerful enough, solar flares can cause interference on Earth, disrupting radio communication networks and navigation systems. This can cause problems for people working in the shipping or aviation industry, among others.

It’s worth noting, however, that an M-class flare probably wouldn’t be particularly disruptive anyway. Although M-class flares are the second most powerful type of solar flare, they typically only cause moderate radio blackout events. An M9 flare, the most powerful of the M-class, could cause loss of radio contact and degradation of low-frequency navigation signals in affected areas of the world for tens of minutes. M-class flares are also common.

It’s the rarer X-class flares that can cause more serious problems. X-class flares are the strongest type of flare. An X20 flare, for example, would cause a complete high-frequency radio blackout on the daylight side of the Earth for several hours, and boats and airplanes would be unable to use navigation signals during that time.

Fortunately, such flares are very rare, estimated to occur less than once every 11 years – the length of an average solar cycle.

solar flares
A file image shows solar flares erupting from the sun. Sunspots are associated with solar flares.
Claudio Ventrella/Getty