Share

Solar Flares Explained: What You Need to Know

Mike Wall
Published: May 15, 2013

Classifying Solar Flares

NASA/SDO

On May 13, 2013, an X2.8-class flare erupted from the sun -- the strongest flare of 2013 to date. This NASA image shows a close-up of the flare as seen by the Solar Dynamics Observatory in the 131 angstrom wavelength.

Solar flares occur when a buildup of magnetic energy on the sun is suddenly released. They usually erupt from sunspots, temporary dark and relatively cool patches on our star's surface where the local magnetic field is very strong.

Flares generate a burst of radiation across a wide range of the electromagnetic spectrum. They're often accompanied by coronal mass ejections (CMEs), which hurl enormous clouds of super-heated plasma into space.

Scientists classify strong solar flares into one of three categories: C, M or X (with A and B classes, too, for weaker eruptions). There's a tenfold increase in power from one class to the next, so an X flare is 10 times stronger than an M flare, and 100 times more powerful than a C.

There's also a finer gradation within each class, from 1 to 9 in the case of C and M flares. But the number goes higher for X flares, because they're at the top of the scale and the sun occasionally fires off eruptions more than 10 times stronger than an X1. For example, in 2003, the sun let loose a flare that registered as an X28 before overwhelming the sensors that measured it. It remains the most powerful solar flare ever recorded.


Featured Blogs

Atlantic Disturbance 96L Still 96L But Threat to US Increases

By Dr. Jeff Masters
August 23, 2014

Heavy Rainfall Trends

By Christopher C. Burt
August 22, 2014

Yet another phenomenally intense rainfall event has occurred in the U.S. this morning (August 22nd) when 3.95” of rain in one hour was measured by a COOP observer at a site 3 miles southwest of Chicago’s Midway Airport. The return period for such at Midway Airport (according to NOAA’s ‘Precipitation Frequency Data Server’) is once in 500 years. This is similar to the Baltimore, Detroit, and Islip, New York events last week (although the Islip event was probably more in the range of once in a 1000 years). Brian Brettschneider of Borealis Scientific LLC has kindly offered this guest blog today featuring research he has done on heavy rainfall trends for 207 sites across the U.S. for a homogenous POR of 1949-2013.

Live Blog: Tracking Hurricane Arthur as it Approaches North Carolina Coast

By Shaun Tanner
July 3, 2014

This is a live blog set up to provide the latest coverage on Hurricane Arthur as it threatens the North Carolina Coast. Check back often to see what the latest is with Arthur. The most recent updates are at the top.

Tropical Terminology

By Stu Ostro
June 30, 2014

Here is some basic, fundamental terminology related to tropical cyclones. Rather than a comprehensive and/or technical glossary, this represents the essence of the meaning & importance of some key, frequently used terms.

2013-14 - An Interesting Winter From A to Z

By Tom Niziol
May 15, 2014

It was a very interesting winter across a good part of the nation from the Rockies through the Plains to the Northeast. Let's break down the most significant winter storms on a month by month basis.

What the 5th IPCC Assessment Doesn't Include

By Angela Fritz
September 27, 2013

Melting permafrost has the potential to release an additional 1.5 trillion tons of carbon into the atmosphere, and could increase our global average temperature by 1.5°F in addition to our day-to-day human emissions. However, this effect is not included in the IPCC report issued Friday morning, which means the estimates of how Earth's climate will change are likely on the conservative side.