Sun  ID: 12706

September Flares

Active region 2673 emitted a series of flares in early September, 2017, including:
--an M5.5 at 4:33 p.m. EDT on Sept. 4, 2017
--an X2.2 at 5:10 a.m. EDT on Sept. 6, 2017
--an X9.3 at 8:02 a.m. EDT on Sept. 6, 2017
--an M7.3 at 6:15 a.m. EDT on Sept. 7, 2017
--an X1.3 at 10:36 a.m. EDT on Sept. 7, 2017
--an M8.1 at 3:49 a.m. EDT on Sept. 8, 2017
--an X8.2 at 12:47 p.m. EDT on Sept. 10, 2017

NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of the events. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel.

To see how this event may affect Earth, please visit NOAA's Space Weather Prediction Center at, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.

The X9.3 flare was the largest flare so far in the current solar cycle, the approximately 11-year-cycle during which the sun’s activity waxes and wanes. The current solar cycle began in December 2008, and is now decreasing in intensity and heading toward solar minimum. This is a phase when such eruptions on the sun are increasingly rare, but history has shown that they can nonetheless be intense.

September 10, X8.2

September 8, M8.1

September 7, X1.3

September 6, X9.3 and X2.2

September 4, M5.5


For More Information


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SVS >> Sun
GCMD >> Earth Science >> Sun-earth Interactions >> Solar Activity >> Solar Flares
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GCMD keywords can be found on the Internet with the following citation: Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version