Editing Solar cycle (section)

=== Solar flares and coronal mass ejections ===
{{Main|Solar flare|Coronal mass ejection}}

The solar magnetic field structures the corona, giving it its characteristic shape visible at times of solar eclipses. Complex coronal magnetic field structures evolve in response to fluid motions at the solar surface, and emergence of [[magnetic flux]] produced by [[solar dynamo|dynamo]] action in the solar interior. For reasons not yet understood in detail, sometimes these structures lose stability, leading to [[solar flare]]s and [[coronal mass ejection]]s (CME). Flares consist of an abrupt emission of energy (primarily at [[ultraviolet]] and [[X-ray]] wavelengths), which may or may not be accompanied by a coronal mass ejection, which consists of injection of energetic particles (primarily ionized hydrogen) into interplanetary space. Flares and CME are caused by sudden localized release of magnetic energy, which drives emission of ultraviolet and X-ray radiation as well as energetic particles. These eruptive phenomena can have a significant impact on Earth's upper atmosphere and space environment, and are the primary drivers of what is now called [[space weather]]. Consequently, the occurrence of both [[geomagnetic storm]]s<ref>{{Cite journal |last1=Owens |first1=Mathew J. |last2=Lockwood |first2=Mike |last3=Barnard |first3=Luke A. |last4=Scott |first4=Chris J. |last5=Haines |first5=Carl |last6=Macneil |first6=Allan |date=2021-05-20 |title=Extreme Space-Weather Events and the Solar Cycle |journal=Solar Physics |language=en |volume=296 |issue=5 |page=82 |doi=10.1007/s11207-021-01831-3 |bibcode=2021SoPh..296...82O |s2cid=236402345 |issn=1573-093X|doi-access=free }}</ref> and [[Solar energetic particles|solar energetic particle]]<ref>{{Cite journal |last1=Owens |first1=Mathew J. |last2=Barnard |first2=Luke A. |last3=Pope |first3=Benjamin J. S. |last4=Lockwood |first4=Mike |last5=Usoskin |first5=Ilya |last6=Asvestari |first6=Eleanna |date=2022-08-19 |title=Solar Energetic-Particle Ground-Level Enhancements and the Solar Cycle |journal=Solar Physics |language=en |volume=297 |issue=8 |page=105 |doi=10.1007/s11207-022-02037-x |arxiv=2207.12787 |bibcode=2022SoPh..297..105O |s2cid=251066764 |issn=1573-093X}}</ref> events shows a strong solar cycle variation, peaking close to sunspot maximum.

The occurrence frequency of coronal mass ejections and flares is strongly modulated by the cycle. Flares of any given size are some 50 times more frequent at solar maximum than at minimum. Large coronal mass ejections occur on average a few times a day at solar maximum, down to one every few days at solar minimum. The size of these events themselves does not depend sensitively on the phase of the solar cycle. A case in point are the three large X-class flares that occurred in December 2006, very near solar minimum; an X9.0 flare on Dec 5 stands as one of the brightest on record.<ref>{{Cite journal
 | title=The Most Powerful Solar Flares Ever Recorded
 | website=Spaceweather.com
 | url=http://www.spaceweather.com/solarflares/topflares.html
 }}</ref>