Related topics: magnetic field · earth · sun · nasa · space weather

The space we travel through

When sea-faring nations began to explore new regions of the world, one of their biggest concerns in making the journey safely was how to cope with weather. They could harness the wind for power. They could rely on the Sun ...

Image: ISS transits the sun

Humankind's most distant outpost was recently captured crossing the face of our enormous and gleaming sun. The fleeting transit of the International Space Station was over in the blink of an eye, but Ian Griffin, Director ...

High-energy X-ray bursts from low-energy plasma

Solar flares shouldn't produce X-rays, but they do. Why? The one-size-fits-all approach to electron collisions misses a lucky few that lead to an intense X-ray burst. Scientists thought there were too many electron-scattering ...

The sun in 2018

This montage of 365 images shows the changing activity of our sun through the eyes of ESA's Proba-2 satellite during 2018. The images were taken by the satellite's SWAP camera, which works at extreme ultraviolet wavelengths ...

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Solar flare

A solar flare is a big explosion in the Sun's atmosphere that can release as much as 6 × 1025 joules of energy. The term is also used to refer to similar phenomena in other stars, where the more accurate term stellar flare applies.

Solar flares affect all layers of the solar atmosphere (photosphere, corona, and chromosphere), heating plasma to tens of millions of kelvins and accelerating electrons, protons, and heavier ions to near the speed of light. They produce radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays. Most flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. If a solar flare is exceptionally powerful, it can cause coronal mass ejections.

X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies.

Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group. Stellar flares have also been observed on a variety of other stars.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one each week when the Sun is "quiet". Large flares are less frequent than smaller ones. Solar activity varies with an 11-year cycle (the solar cycle). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares.

This text uses material from Wikipedia, licensed under CC BY-SA