Editing Solar wind (section)

{{Short description|Stream of charged particles from the Sun}}
{{Other uses}}
{{Heliophysics}}
{{Geophysics|all}}

[[File:Solar wind Speed interplanetary magnetic field.jpg|thumb|upright=1.25|[[Ulysses (spacecraft)|''Ulysses'']]'s observations of solar wind speed as a function of helio latitude during solar minimum. Slow wind (≈{{val|400|u=km/s}}) is confined to the equatorial regions, while fast wind (≈{{val|750|u=km/s}}) is seen over the poles.<ref name="McComas 1517">{{Cite journal|last1=McComas|first1=D. J.|last2=Elliott|first2=H. A.|last3=Schwadron|first3=N. A.|last4=Gosling|first4=J. T.|last5=Skoug|first5=R. M.|last6=Goldstein|first6=B. E.|date=2003-05-15|title=The three-dimensional solar wind around solar maximum|journal=Geophysical Research Letters|language=en|volume=30|issue=10|pages=1517|doi=10.1029/2003GL017136|issn=1944-8007|bibcode = 2003GeoRL..30.1517M |doi-access=free}}</ref> Red/blue colors show outward/inward polarities of the [[heliospheric magnetic field]].]]
The '''solar wind''' is a stream of [[charged particle]]s released from the [[Sun]]'s outermost atmospheric layer, the [[Stellar corona|corona]]. This [[Plasma (physics)|plasma]] mostly consists of [[electron]]s, [[proton]]s and [[alpha particle]]s with [[kinetic energy]] between {{val|0.5|and|10|ul=keV}}. The composition of the solar wind plasma also includes a mixture of particle species found in the solar plasma: trace amounts of heavy ions and [[atomic nuclei]] of [[Chemical element|elements]] such as [[carbon]], [[nitrogen]], [[oxygen]], [[neon]], [[magnesium]], [[silicon]], [[sulfur]], and [[iron]]. There are also rarer traces of some other nuclei and isotopes such as [[phosphorus]], [[titanium]], [[chromium]], and [[nickel]]'s [[isotopes]] <sup>58</sup>Ni, <sup>60</sup>Ni, and <sup>62</sup>Ni.<ref>{{Cite web|url=http://solar-center.stanford.edu/FAQ/Qsolwindcomp.html|title=Stanford SOLAR Center – Ask A Solar Physicist FAQs – Answer|website=solar-center.stanford.edu|access-date=2019-11-09}}</ref> Superimposed with the solar-wind plasma is the [[interplanetary magnetic field]].<ref>{{Cite journal|last1=Owens|first1=Mathew J.|last2=Forsyth|first2=Robert J.|date=2013-11-28|title=The Heliospheric Magnetic Field|journal=Living Reviews in Solar Physics|language=en|volume=10|issue=1|pages=5|doi=10.12942/lrsp-2013-5|doi-access=free |issn=2367-3648|bibcode = 2013LRSP...10....5O |arxiv=1002.2934|s2cid=122870891}}</ref> The solar wind varies in [[density]], [[temperature]] and [[speed]] over time and over [[Solar coordinate systems#Heliographic|solar latitude and longitude]]. Its particles can escape the Sun's [[gravity]] because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the [[Alfvén surface]].

At a distance of more than a few [[solar radii]] from the Sun, the solar wind reaches speeds of {{val|250|–|750|ul=km/s}} and is supersonic,<ref>McGRAW-HILL ENCYCLOPEDIA OF Science & Technology, 8th ed., (c)1997, vol. 16, page 685</ref> meaning it moves faster than the speed of [[fast magnetosonic wave]]s. The flow of the solar wind is no longer supersonic at the [[termination shock]]. Other related phenomena include the [[aurora]] (northern and southern lights), [[comet tail]]s that always point away from the Sun, and [[geomagnetic storm]]s that can change the direction of magnetic field lines.