Editing Solar wind (section)

==={{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>