Coronal rain

{{Short description|Plasma falling to the Sun's photosphere}}

File:Coronal Rain.ogv. The footage in this video was collected by the Solar Dynamics Observatory's AIA instrument. SDO collected one frame every 12 seconds so each second in this video corresponds to 6 minutes of real time. The video covers 4:30 UTC on July 19th to 2:00 UTC on July 20th, a period of 21 hours and 30 minutes.]]

Coronal rain is a phenomenon that occurs in the Sun's corona when hot plasma cools and condenses in strong magnetic fields and falls to the photosphere. It is usually associated with active regions, most obviously in the aftermath of a solar flare.{{cite web|last=Jauregui|first=Andres|title=Coronal Rain: Solar Flare Rains Fire On Sun In NASA VIDEO|date=21 February 2013 |url=http://www.huffingtonpost.com/2013/02/21/coronal-rain-solar-flare-video_n_2733623.html|publisher=huffingtonpost.com|accessdate=14 March 2014}}{{cite web|last=Grossman|first=Lisa|title=Video: Coronal Rain Shower Caught on Sun|url=https://www.wired.com/wiredscience/2011/06/coronal-rain-video/|publisher=wired.com|accessdate=14 March 2014}}{{cite web|title=NASA Video Shows Stunning Coronal Rainstorm on Sun|date=22 February 2013 |url=https://www.voanews.com/a/stunning-coronal-rainstorm-on-sun-depicted-in-nasa-video/1608933.html|publisher=Voice of America|access-date=14 March 2014|archive-url=https://web.archive.org/web/20140314102252/http://www.voanews.com/content/stunning-coronal-rainstorm-on-sun-depicted-in-nasa-video/1608933.html|archive-date=14 March 2014|url-status=live}}{{cite web|last=Shiga|first=David|title=Sun's rain could explain why corona heat is insane|url=https://www.newscientist.com/article/dn18020-suns-rain-could-explain-why-corona-heat-is-insane.html#.UyLAHz-SyBI|publisher=newscientist.com|accessdate=14 March 2014}}{{cite web|last=O'NEILL|first=IAN|title=The Sun's Coronal Rain Puzzle Solved|url=http://news.discovery.com/space/unlocking-the-suns-coronal-rain-mystery.htm|publisher=news.discovery.com|accessdate=14 March 2014}}{{cite web|last=Antolin/Verwichte|first=P./ and E. (Erwin)|title=Transverse oscillations of loops with coronal rain observed by hinode/solar optical telescope|url=http://wrap.warwick.ac.uk/40031/|publisher=wrap.warwick.ac.uk|accessdate=14 March 2014|archive-url=https://web.archive.org/web/20140314105752/http://wrap.warwick.ac.uk/40031/|archive-date=14 March 2014|url-status=dead}}

Coronal rain can also form after injection of material via impulsive heating anywhere in the solar atmosphere, for example in association with magnetic reconnection.{{Cite journal |last1=Kohutova |first1=P. |last2=Verwichte |first2=E. |last3=Froment |first3=C. |date=2019-10-01 |title=Formation of coronal rain triggered by impulsive heating associated with magnetic reconnection |url=https://www.aanda.org/articles/aa/abs/2019/10/aa36253-19/aa36253-19.html |journal=Astronomy & Astrophysics |language=en |volume=630 |pages=A123 |doi=10.1051/0004-6361/201936253 |issn=0004-6361|arxiv=1910.07746 |bibcode=2019A&A...630A.123K }}

The material that makes up the coronal rain can be up to hundreds of times cooler than the surrounding environment.{{Cite web |last=Pastor |first=Adelina |title=Coronal rain |url=https://est-east.eu/?option=com_content&view=article&id=805&lang=en&Itemid=622 |access-date=2024-05-17 |website=European Solar Telescope |language=en-gb}}