Editing Solar wind (section)

==Solar System effects==
{{Main|Space weather}}
[[File:Heliospheric-current-sheet.gif|thumb|upright=1.2|The [[heliospheric current sheet]] results from the influence of the Sun's rotating magnetic field on the plasma in the solar wind.]]

Over the Sun's lifetime, the interaction of its surface layers with the escaping solar wind has significantly decreased its surface rotation rate.<ref>{{cite journal
 | last=Endal | first=A. S. |author2=Sofia, S.
  | title=Rotation in solar-type stars. I – Evolutionary models for the spin-down of the Sun
 | journal=Astrophysical Journal, Part 1
 | date=1981 | volume=243 | pages=625–640
 | bibcode=1981ApJ...243..625E
 | doi=10.1086/158628 }}</ref> The wind is considered responsible for comets' tails, along with the Sun's radiation.<ref>{{cite book|author=Robin Kerrod|title=Asteroids, Comets, and Meteors|url=https://archive.org/details/asteroidscometsm00robi|url-access=registration|publisher=Lerner Publications, Co.|date=2000}}</ref> The solar wind contributes to fluctuations in [[Sky|celestial]] [[radio wave]]s observed on the Earth, through an effect called [[interplanetary scintillation]].<ref name="scint">{{cite journal | author = Jokipii, J.R. | title = Turbulence and Scintillations in the Interplanetary Plasma | journal = Annual Review of Astronomy and Astrophysics | volume = 11 | issue = 1 | pages = 1–28 | date = 1973 | doi = 10.1146/annurev.aa.11.090173.000245 | bibcode = 1973ARA&A..11....1J}}</ref>

===Magnetospheres===
{{Main|Magnetosphere}}
[[File:Structure_of_the_magnetosphere_LanguageSwitch.svg|lang=en|thumb|upright=1.5|Schematic of Earth's [[magnetosphere]]. The solar wind flows from left to right.]]

Where the solar wind intersects with a planet that has a well-developed [[magnetic field]] (such as Earth, Jupiter or Saturn), the particles are deflected by the [[Lorentz force]]. This region, known as the [[magnetosphere]], causes the particles to travel around the planet rather than bombarding the atmosphere or surface. The magnetosphere is roughly shaped like a [[Sphere|hemisphere]] on the side facing the Sun, then is drawn out in a long wake on the opposite side. The boundary of this region is called the [[magnetopause]], and some of the particles are able to penetrate the magnetosphere through this region by partial reconnection of the magnetic field lines.<ref name="encrenaz" />

[[File:Solar Wind and Earth's magnetic field.png|thumb|Noon meridian section of magnetosphere]]

The solar wind is responsible for the overall shape of Earth's magnetosphere. Fluctuations in its speed, density, direction, and [[Interplanetary magnetic field|entrained magnetic field]] strongly affect Earth's local space environment. For example, the levels of ionizing radiation and radio interference can vary by factors of hundreds to thousands; and the shape and location of the magnetopause and bow [[shock wave]] upstream of it can change by several Earth radii, exposing [[Geosynchronous orbit|geosynchronous]] satellites to the direct solar wind. These phenomena are collectively called [[space weather]].

From the [[European Space Agency]]'s [[Cluster II (spacecraft)|Cluster]] mission, a new study has taken place that proposes that it is easier for the solar wind to infiltrate the magnetosphere than previously believed. A group of scientists directly observed the existence of certain waves in the solar wind that were not expected. A recent study shows that these waves enable incoming charged particles of solar wind to breach the magnetopause. This suggests that the magnetic bubble forms more as a filter than a continuous barrier. This latest discovery occurred through the distinctive arrangement of the four identical Cluster spacecraft, which fly in a controlled configuration through near-Earth space. As they sweep from the magnetosphere into interplanetary space and back again, the fleet provides exceptional three-dimensional insights on the phenomena that connect the sun to Earth.

The research characterised variances in formation of the [[interplanetary magnetic field]] (IMF) largely influenced by [[Kelvin–Helmholtz instability]] (which occur at the interface of two fluids) as a result of differences in thickness and numerous other characteristics of the boundary layer. Experts believe that this was the first occasion that the appearance of Kelvin–Helmholtz waves at the magnetopause had been displayed at high latitude downward orientation of the IMF. These waves are being seen in unforeseen places under solar wind conditions that were formerly believed to be undesired for their generation. These discoveries show how Earth's magnetosphere can be penetrated by solar particles under specific IMF circumstances. The findings are also relevant to studies of magnetospheric progressions around other planetary bodies. This study suggests that Kelvin–Helmholtz waves can be a somewhat common, and possibly constant, instrument for the entrance of solar wind into terrestrial magnetospheres under various IMF orientations.<ref>NASA Study Using Cluster Reveals New Insights Into Solar Wind, NASA, Greenbelt, 2012, p.1</ref>

==={{anchor|Atmospheres}}Atmospheres===
The solar wind affects other incoming [[cosmic ray]]s interacting with planetary atmospheres. Moreover, planets with a weak or non-existent magnetosphere are subject to atmospheric stripping by the solar wind.

[[Venus]], the nearest and most similar planet to Earth, has 100 times denser atmosphere, with little or no geo-magnetic field. Space probes discovered a comet-like tail that extends to Earth's orbit.<ref>{{cite journal |author=Grünwaldt H|display-authors=etal |date=1997 |title=Venus tail ray observation near Earth |journal=Geophysical Research Letters |volume=24 |issue=10 |pages=163–1166 |url=https://scholar.google.com/scholar?num=100&hl=en&lr=&safe=active&cluster=13741676747552292586 | doi = 10.1029/97GL01159 |bibcode=1997GeoRL..24.1163G|doi-access=free }}</ref>

Earth itself is largely protected from the solar wind by [[Earth's magnetic field|its magnetic field]], which deflects most of the charged particles; however, some of the charged particles are trapped in the [[Van Allen radiation belt]]. A smaller number of particles from the solar wind manage to travel, as though on an electromagnetic energy transmission line, to the Earth's upper atmosphere and [[ionosphere]] in the auroral zones. The only time the solar wind is observable on the Earth is when it is strong enough to produce phenomena such as the [[aurora (astronomy)|aurora]] and [[geomagnetic storm]]s. Bright auroras strongly heat the ionosphere, causing its plasma to expand into the magnetosphere, increasing the size of the plasma [[geosphere]] and injecting atmospheric matter into the solar wind. Geomagnetic storms result when the pressure of plasmas contained inside the magnetosphere is sufficiently large to inflate and thereby distort the geomagnetic field.

Although [[Mars]] is larger than Mercury and four times farther from the Sun, it is thought that the solar wind has stripped away up to a third of its original atmosphere, leaving a layer 1/100 as dense as the Earth's. It is believed the mechanism for this atmospheric stripping is gas caught in bubbles of the magnetic field, which are ripped off by the solar wind.<ref>{{cite web|url=http://archive.cosmosmagazine.com/news/solar-wind-ripping-chunks-mars/|title=Solar wind ripping chunks off Mars -|url-status=dead|archive-url=https://web.archive.org/web/20160304072916/http://archive.cosmosmagazine.com/news/solar-wind-ripping-chunks-mars/|archive-date=2016-03-04}}</ref> In 2015 the NASA Mars Atmosphere and Volatile Evolution ([[MAVEN]]) mission measured the rate of atmospheric stripping caused by the magnetic field carried by the solar wind as it flows past Mars, which generates an electric field, much as a turbine on Earth can be used to generate electricity. This electric field accelerates electrically charged gas atoms, called ions, in Mars's upper atmosphere and shoots them into space.<ref>{{cite web|title=NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere|author=NASA|work=Mars Atmosphere and Volatile Evolution (MAVEN) mission|url=http://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere|access-date=2015-11-05|date=2015-11-05}}</ref> The MAVEN mission measured the rate of atmospheric stripping at about 100 grams (≈1/4&nbsp;lb) per second.<ref name=MAVEN-tweet>{{Cite tweet|user=MAVEN2Mars|number=662377165426585603|date=November 5, 2015|title=NASA MAVEN mission measures solar wind atmospheric stripping on Mars}}</ref>

===Moons and planetary surfaces===
[[File:Aldrin Next to Solar Wind Experiment - GPN-2000-001211.jpg|thumb|upright=0.8|Apollo's [[Solar Wind Composition Experiment|SWC]] experiment]]
[[File:AS11-40-5916.jpg|thumb|upright=0.8|Apollo's [[Solar Wind Composition Experiment]] on the Lunar surface]]
[[Mercury (planet)|Mercury]], the nearest planet to the Sun, bears the full brunt of the solar wind, and since its atmosphere is vestigial and transient, its surface is bathed in radiation.

Mercury has an intrinsic magnetic field, so under normal solar wind conditions, the solar wind cannot penetrate its magnetosphere and particles only reach the surface in the cusp regions. During coronal mass ejections, however, the magnetopause may get pressed into the surface of the planet, and under these conditions, the solar wind may interact freely with the planetary surface.

The Earth's [[Moon]] has no atmosphere or intrinsic [[Magnetosphere|magnetic field]], and consequently its surface is bombarded with the full solar wind. The [[Apollo program|Project Apollo missions]] deployed passive aluminum collectors in an attempt to sample the solar wind, and lunar soil returned for study confirmed that the lunar [[regolith]] is enriched in atomic nuclei deposited from the solar wind. These elements may prove [[Lunar resources|useful resources]] for future lunar expeditions.<ref>{{Cite journal | last1 = Starukhina | first1 = L. V. | doi = 10.1016/j.asr.2005.04.033 | title = Polar regions of the moon as a potential repository of solar-wind-implanted gases | journal = Advances in Space Research | volume = 37 | issue = 1 | pages = 50–58 | year = 2006 |bibcode = 2006AdSpR..37...50S }}</ref>