What are X flares? Can they harm us?

Article originally published by NASA. Edits by EarthSky. Read the original article here.

What are X flares?

Solar flares are giant explosions on the sun that might send energy, light and high-speed particles into space. The biggest are known as X flares!

The standard classification system divides solar flares according to their strength. The smallest ones are A-class (near background levels), followed by B, C, M and X. Like the Richter scale for earthquakes, each letter represents a 10-fold increase in energy output. So an X is 10 times a M and 100 times a C. And then, within each letter class, there’s a finer scale from 1 to 9.

The frequency of solar flares increases approximately every 11 years. And the sun is currently moving towards another solar maximum. The peak of the current cycle will likely come around 2025.

That’s why we’ve seen an uptick in flares on the sun over this past year. Many are small, but some are big. We’ve seen several X flares recently, too, including the X2.2 flare from sunspot region AR3229 on February 17. The result – so far – has been many beautiful displays of the aurora or northern lights.

But are X flares dangerous?

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X-class flares: Part of the sun, shown in blue, with an animated bright flash on the upper edge.
The sun produced this X2.2 flare from sunspot region AR3229 on February 17, 2023. Not all X-class flares impact the Earth, but this one produced a fast CME with an Earth-directed component. Image via SDO/ AIA/ EVE/ HMI.

M and X flares and their effects

C flares and smaller flares are too weak to affect Earth in any noticeable way.

Meanwhile, both M flares and X flares can cause brief radio blackouts on Earth.

And both M and X flares are known to release coronal mass ejections (CMEs), great clumps of superheated matter and accompanying magnetic fields. This solar material travels outward through our solar system, and sometimes gives Earth’s atmosphere a glancing blow, or even strikes it directly.

Can it harm us? Generally speaking, no. Here on Earth’s surface, Earth’s atmosphere protects us from harm. Some people do say they notice effects from solar flaring, although – among scientists – these possible effects are still a matter for debate.

And, meanwhile, big CMEs have been known to interrupt earthly technologies: satellites and power grids.

X flares can get big!

There are flares more than 10 times the power of an X1. So X-class flares can go higher than 9. To date, the most powerful solar flare measured with modern methods was in 2003, during a solar maximum. That flare was so powerful that it overloaded the sensors measuring it. The sensors cut out at X28 and the flare was later estimated to be X45.

The Solar and Heliospheric Observatory (SOHO) spacecraft captured this image of a that powerful solar flare as it erupted from the sun in 2003.

X flares are extremely powerful

Overall, the biggest X-class flares are by far the largest explosions in our solar system. And they are awesome to watch. Loops tens of times the size of Earth leap up off the sun’s surface, as the sun’s magnetic fields cross over each other and reconnect. In the biggest events, this reconnection process can produce as much energy as a billion hydrogen bombs.

That’s one reason NASA and NOAA – as well as others – constantly watch the sun to monitor for X-class flares and their associated magnetic storms. With advance warning, these scientists have a system for protecting many satellites and spacecraft from the worst effects of most magnetic storms.

Since the current solar cycle – Solar Cycle 25 – is now rising to a peak, watch for some strong X-class flares. Visit our sun activity post for daily updates

Bottom line: X flares on the sun are the most powerful explosions in the solar system. We’re likely to see more of them as we approach solar maximum, due around 2025.


Visit our sun activity post for daily updates

March 1, 2023

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