Editing Magnetosphere (section)

===Other objects===
Many astronomical objects generate and maintain magnetospheres. In the Solar System this includes the Sun, [[Mercury (planet)|Mercury]], [[Earth]], [[Jupiter]], [[Saturn]], [[Uranus]], [[Neptune]],<ref name="Planetary Shields: Magnetospheres">{{cite web |title=Planetary Shields: Magnetospheres |url=https://mobile.arc.nasa.gov/public/iexplore/missions/pages/yss/november2011.html |publisher=NASA |access-date=5 January 2020}}</ref> and [[Ganymede (moon)|Ganymede]]. The [[magnetosphere of Jupiter]] is the largest planetary magnetosphere in the Solar System, extending up to {{convert|7000000|km|sp=us}} on the dayside and almost to the orbit of [[Saturn]] on the nightside.<ref>{{cite encyclopedia |url=http://www.igpp.ucla.edu/people/mkivelson/Publications/279-Ch24.pdf |title=The configuration of Jupiter's magnetosphere |first=K. K. |last=Khurana |author2=Kivelson, M. G. |display-authors=etal |isbn=978-0-521-81808-7 |encyclopedia=Jupiter: The Planet, Satellites and Magnetosphere |publisher=[[Cambridge University Press]] |editor=Bagenal, Fran |editor2=Dowling, Timothy E. |editor3=McKinnon, William B. |date=2004 }}</ref> Jupiter's magnetosphere is stronger than Earth's by an [[order of magnitude]], and its [[magnetic moment]] is approximately 18,000 times larger.<ref>{{cite journal|last=Russell|first=C.T.|title=Planetary Magnetospheres|journal=Reports on Progress in Physics|volume=56|issue=6|pages=687–732|date=1993|doi=10.1088/0034-4885/56/6/001|bibcode=1993RPPh...56..687R|s2cid=250897924 }}</ref> [[Venus]], [[Mars]], and [[Pluto]], on the other hand, have no ''intrinsic'' magnetic field. This may have had significant effects on their geological history. It is hypothesized that Venus and Mars may have lost their primordial water to [[photodissociation]] and the solar wind. A strong magnetosphere, were it present, would greatly slow down this process.<ref name="Planetary Shields: Magnetospheres"/><ref>{{cite web |title=X-ray Detection Sheds New Light on Pluto |url=https://www.nasa.gov/mission_pages/chandra/x-ray-detection-sheds-new-light-on-pluto.html |access-date=3 December 2016 |date=14 September 2016 |author=NASA |website=nasa.gov}}</ref> 

[[File:Tau Bootis b.jpg|right|thumb|Artist impression of the magnetic field around Tau Boötis b detected in 2020.]]
{| class="wikitable sortable mw-collapsible"
|+Magnetospheres of the Solar System<ref name="n675">{{cite book |last1=Kivelson |first1=Margaret Galland |title=Encyclopedia of the Solar System |last2=Bagenal |first2=Fran |publisher=Elsevier |year=2014 |isbn=978-0-12-415845-0 |pages=137–157 |chapter=Planetary Magnetospheres |doi=10.1016/b978-0-12-415845-0.00007-4}}</ref>
!Magnetosphere
!Surface equatorial field ([[Tesla (unit)|microteslas]])
!{{Sfrac|Distance to [[magnetopause]]|Planetary radius}}
!Upstream
[[Alfvén Mach number]]
!{{Sfrac|Surface [[magnetic pressure]]|Exterior [[magnetic pressure]]}}
!{{Sfrac|Solar wind speed|Rotation speed}} at magnetopause
|-
|[[Magnetosphere of Mercury|Mercury]]
|0.14-04
|1.5
|6
|1
|{{Val|3e5}}
|-
|[[Earth's magnetic field|Earth]]
|31
|10
|7
|{{Val|4e5}}
|90
|-
|[[Magnetosphere of Mars|Mars]]
|<0.01
|n/a
|8
|<0.04
|n/a
|-
|[[Magnetosphere of Jupiter|Jupiter]]
|428
|70
|10
|{{Val|7e8}}
|0.4
|-
|[[Magnetosphere of Ganymede|Ganymede]]
|0.72
|1.6
|0.4
|50
|n/a
|-
|[[Magnetosphere of Saturn|Saturn]]
|22
|20
|12
|{{Val|7e7}}
|2
|-
|[[Magnetosphere of Uranus|Uranus]]
|23
|18
|13
|{{Val|4e7}}
|7
|-
|[[Magnetosphere of Neptune|Neptune]]
|14
|24
|15
|{{Val|4e7}}
|6
|}
Magnetospheres generated by [[exoplanet]]s are thought to be common, though the first discoveries did not come until the 2010s. In 2014, a magnetic field around [[HD 209458 b]] was inferred from the way [[hydrogen]] was evaporating from the planet.<ref>{{Cite web|author1=Charles Q. Choi|date=2014-11-20|title=Unlocking the Secrets of an Alien World's Magnetic Field|url=https://www.space.com/27828-alien-planet-magnetic-field-strength.html|access-date=2022-01-17|website=Space.com|language=en}}</ref><ref>{{Cite journal|doi=10.1126/science.1257829|pmid=25414310 |title=Magnetic moment and plasma environment of HD 209458b as determined from Ly observations |journal=Science |volume=346 |issue=6212 |pages=981–984 |year=2014 |last1=Kislyakova |first1=K. G.|last2=Holmstrom |first2=M. |last3=Lammer |first3=H. |last4=Odert |first4=P. |last5=Khodachenko |first5=M. L. |bibcode=2014Sci...346..981K |arxiv = 1411.6875 |s2cid=206560188}}</ref> In 2019, the strength of the surface magnetic fields of 4 [[hot Jupiter]]s were estimated and ranged between 20 and 120 [[Gauss (unit)|gauss]] compared to Jupiter's surface magnetic field of 4.3 gauss.<ref>{{Cite web|author1=Passant Rabie|date=2019-07-29|title=Magnetic Fields of 'Hot Jupiter' Exoplanets Are Much Stronger Than We Thought|url=https://www.space.com/hot-jupiter-magnetic-fields-measured-for-first-time.html|access-date=2022-01-17|website=Space.com|language=en}}</ref><ref>{{Cite journal|last1=Cauley|first1=P. Wilson|last2=Shkolnik|first2=Evgenya L.|last3=Llama|first3=Joe|last4=Lanza|first4=Antonino F.|date=Dec 2019|title=Magnetic field strengths of hot Jupiters from signals of star-planet interactions|journal=Nature Astronomy|volume=3|issue=12|pages=1128–1134|doi=10.1038/s41550-019-0840-x|arxiv=1907.09068|bibcode=2019NatAs...3.1128C|s2cid=198147426|issn=2397-3366}}</ref> In 2020, a radio emission in the 14-30&nbsp;MHz band was detected from the [[Tau Boötis]] system, likely associated with [[cyclotron radiation]] from the poles of [[Tau Boötis b]] which might be a signature of a planetary magnetic field.<ref>{{citation |last1=Turner |first1=Jake D. |title=The search for radio emission from the exoplanetary systems 55 Cancri, υ Andromedae, and τ Boötis using LOFAR beam-formed observations |journal=Astronomy & Astrophysics |volume=645 |pages=A59 |year=2021 |arxiv=2012.07926 |bibcode=2021A&A...645A..59T |doi=10.1051/0004-6361/201937201 |s2cid=212883637 |last2=Zarka |first2=Philippe |last3=Grießmeier |first3=Jean-Mathias |last4=Lazio |first4=Joseph |last5=Cecconi |first5=Baptiste |last6=Emilio Enriquez |first6=J. |last7=Girard |first7=Julien N. |last8=Jayawardhana |first8=Ray |last9=Lamy |first9=Laurent |last10=Nichols |first10=Jonathan D. |last11=De Pater |first11=Imke}}</ref><ref>{{Cite web |last=O'Callaghan |first=Jonathan |date=2023-08-07 |title=Exoplanets Could Help Us Learn How Planets Make Magnetism |url=https://www.quantamagazine.org/exoplanets-could-help-us-learn-how-planets-make-magnetism-20230807/ |access-date=2023-08-07 |website=Quanta Magazine |language=en}}</ref> In 2021 a magnetic field generated by the [[hot Neptune]] [[HAT-P-11b]] became the first to be confirmed.<ref name= sedHatp11b>[http://data.iap.fr/doi/bjaffel/20210727/ HAT-P-11 Spectral Energy Distribution] Signatures of Strong Magnetization and Metal-poor Atmosphere for a Neptune-Size Exoplanet, Ben-Jaffel et al. 2021</ref> The first unconfirmed detection of a magnetic field generated by a terrestrial exoplanet was found in 2023 on [[YZ Ceti b]].<ref name="Pineda2023">{{cite journal |last1=Pineda |first1=J. Sebastian |last2=Villadsen |first2=Jackie |date=April 2023 |title=Coherent radio bursts from known M-dwarf planet host YZ Ceti |journal=[[Nature Astronomy]] |volume=7 |issue= 5|pages=569–578 |doi=10.1038/s41550-023-01914-0 |arxiv=2304.00031 |bibcode=2023NatAs...7..569P}}</ref><ref name="Trigilio2023">{{cite arXiv |last1=Trigilio |first1=Corrado |last2=Biswas |first2=Ayan |display-authors=etal |date=May 2023 |title=Star-Planet Interaction at radio wavelengths in YZ Ceti: Inferring planetary magnetic field |eprint=2305.00809 |class=astro-ph.EP}}</ref><ref>{{Cite web |date=2023-04-10 |title=A magnetic field on a nearby Earth-sized exoplanet? |url=https://earthsky.org/space/magnetic-field-exoplanets-yz-ceti-b/ |access-date=2023-08-07 |website=earthsky.org |language=en-US}}</ref><ref>{{Cite web |last=O'Callaghan |first=Jonathan |date=7 August 2023 |title=Exoplanets Could Help Us Learn How Planets Make Magnetism |url=https://www.quantamagazine.org/exoplanets-could-help-us-learn-how-planets-make-magnetism-20230807/ |website=[[Quanta Magazine]]}}</ref>