View source for Gravitation of the Moon

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[[File:Earth vs Mars gravity at elevation.webp|thumb|300px|[[Gravity of Earth|Earth]] vs [[Gravity of Mars|Mars]] vs [[Moon]] [[gravity]] at [[elevation]]]]
[[image:MoonLP150Q grav 150.jpg|right|thumb|300px|Radial gravity anomaly at the surface of the Moon in [[Gal (acceleration)|mGal]]]]

The [[gravitational acceleration|acceleration due to gravity]] on the surface of the [[Moon]] is approximately 1.625&nbsp;m/s<sup>2</sup>, about 16.6% that on Earth's surface or 0.166 {{math|[[standard gravity|''ɡ'']]}}.<ref>{{cite journal
 |author1=C. Hirt |author2=W. E. Featherstone |date=2012
 |title=A 1.5 km-resolution gravity field model of the Moon
 |url=http://espace.library.curtin.edu.au:80/R?func=dbin-jump-full&local_base=gen01-era02&object_id=173470
 |journal=Earth and Planetary Science Letters
 |volume=329–330 |pages=22–30
 |bibcode=2012E&PSL.329...22H
 |doi=10.1016/j.epsl.2012.02.012
 |access-date=2012-08-21
}}</ref> Over the entire surface, the variation in gravitational acceleration is about 0.0253&nbsp;m/s<sup>2</sup> (1.6% of the acceleration due to gravity). Because [[weight]] is directly dependent upon gravitational acceleration, things on the Moon will weigh only 16.6% (= 1/6) of what they weigh on the Earth.

==Gravitational field==
The [[gravity|gravitational field]] of the Moon has been measured by tracking the radio signals emitted by orbiting spacecraft. The principle used depends on the [[Doppler effect]], whereby the line-of-sight spacecraft acceleration can be measured by small shifts in frequency of the radio signal, and the measurement of the distance from the spacecraft to a station on Earth. Since the gravitational field of the Moon affects the [[orbit]] of a spacecraft, one can use this tracking data to detect [[gravity anomaly|gravity anomalies]].

Most low lunar orbits are unstable.  Detailed data collected has shown that for low lunar orbit the only "[[Frozen orbit|stable]]" orbits are at inclinations near 27°, 50°, 76°, and 86°.<ref name=nasa20061106>{{cite web |title=Bizarre Lunar Orbits |url=https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ |last=Bell |first=Trudy E. |date=November 6, 2006 |editor-last=Phillips |editor-first=Tony |work=Science@NASA |publisher=[[NASA]] |accessdate=2017-09-08 |archive-date=2021-12-04 |archive-url=https://web.archive.org/web/20211204040014/https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ |url-status=dead }}</ref> Because of the Moon's [[synchronous rotation]] it is not possible to track spacecraft from Earth much beyond the [[Lunar limb|limbs of the Moon]], so until the recent [[Gravity Recovery and Interior Laboratory]] (GRAIL) mission the far-side gravity field was not well mapped.

[[image:Moon gravity acceleration map LGM2011.jpg|right|thumb|300px|Gravity acceleration at the surface of the Moon in m/s<sup>2</sup>. Near side on the left, far side on the right. Map from [http://geodesy.curtin.edu.au/research/models/lgm2011/ Lunar Gravity Model 2011] {{Webarchive|url=https://web.archive.org/web/20130114015408/http://geodesy.curtin.edu.au/research/models/lgm2011/ |date=2013-01-14 }}.]]The missions with accurate Doppler tracking that have been used for deriving gravity fields are in the accompanying table. The table gives the mission spacecraft name, a brief designation, the number of mission spacecraft with accurate tracking, the country of origin, and the time span of the Doppler data. Apollos 15 and 16 released subsatellites. The Kaguya/SELENE mission had tracking between 3 satellites to get far-side tracking. GRAIL had very accurate tracking between 2 spacecraft and tracking from Earth.
{| class="wikitable"
|+Missions Used for Lunar Gravity &nbsp;
!Mission
!ID
!Number
!Source
!Years
|-
|[[Lunar Orbiter 1]]
|LO1
|1
|US
|1966
|-
|[[Lunar Orbiter 2]]
|LO2
|1
|US
|1966–1967
|-
|[[Lunar Orbiter 3]]
|LO3
|1
|US
|1967
|-
|[[Lunar Orbiter 4]]
|LO4
|1
|US
|1967
|-
|[[Lunar Orbiter 5]]
|LO5
|1
|US
|1967–1968
|-
|[[Apollo 15]] Subsatellite
|A15
|1
|US
|1971–1972
|-
|[[Apollo 16]] Subsatellite
|A16
|1
|US
|1972
|-
|[[Clementine (spacecraft)|Clementine]]
|Cl
|1
|US
|1994
|-
|[[Lunar Prospector]]
|LP
|1
|US
|1998–1999
|-
|[[SELENE|Kaguya/SELENE]]
|K/S
|3
|Japan
|2007–2009
|-
|[[Chang'e 1|Chang’e 1]]
|Ch1
|1
|China
|2007–2009
|-
|[[GRAIL]]
|G
|2
|US
|2012
|-
|[[Chang’e 5T1]]
|Ch1T1
|1
|China
|2015–2018
|}
The accompanying table below lists lunar gravity fields. The table lists the designation of the gravity field, the highest degree and order, a list of mission IDs that were analyzed together, and a citation. Mission ID LO includes all 5 Lunar Orbiter missions. The GRAIL fields are very accurate; other missions are not combined with GRAIL.
{| class="wikitable"
|+Lunar Gravity Fields
!Designation
!Degree
!Mission IDs
!Citation
|-
|LP165P 
|165
|LO A15 A16 Cl LP
|<ref name=":3" />
|-
|GLGM3
|150
|LO A15 A16 Cl LP
|<ref>{{Cite journal|last1=Mazarico|first1=E.|last2=Lemoine|first2=F. G.|last3=Han|first3=Shin-Chan|last4=Smith|first4=D. E.|date=2010|title=GLGM-3: A degree-150 lunar gravity model from the historical tracking data of NASA Moon orbiters|journal=Journal of Geophysical Research|language=en|volume=115| issue=E5|pages=E05001, 1–14|doi=10.1029/2009JE003472|bibcode=2010JGRE..115.5001M|issn=0148-0227|doi-access=free}}</ref>
|-
|CEGM01
|50
|Ch 1
|<ref>{{Cite journal|last1=Jianguo|first1=Yan|last2=Jinsong|first2=Ping|last3=Fei|first3=Li| last4=Jianfeng|first4=Cao|last5=Qian|first5=Huang| last6=Lihe|first6=Fung|date=2010| title=Chang'E-1 precision orbit determination and lunar gravity field solution |url=https://linkinghub.elsevier.com/retrieve/pii/S0273117710001559|journal=Advances in Space Research|language=en|volume=46|issue=1|pages=50–57| doi=10.1016/j.asr.2010.03.002|bibcode=2010AdSpR..46...50J}}</ref>
|-
|SGM100h
|100
|LO A15 A16 Cl LP K/S
|<ref>{{Cite journal|last1=Matsumoto|first1=K.|last2=Goossens|first2=S.|last3=Ishihara|first3=Y.|last4=Liu|first4=Q.|last5=Kikuchi|first5=F.|last6=Iwata|first6=T.|last7=Namiki|first7=N.|last8=Noda|first8=H.|last9=Hanada|first9=H.|last10=Kawano|first10=N.|last11=Lemoine|first11=F. G.|display-authors=9|date=2010|title=An improved lunar gravity field model from SELENE and historical tracking data: Revealing the farside gravity features|journal=Journal of Geophysical Research|language=en|volume=115|issue=E6|pages=E06007, 1–20|doi=10.1029/2009JE003499|bibcode=2010JGRE..115.6007M|issn=0148-0227|doi-access=free}}</ref>
|-
|SGM150J
|150
|LO A15 A16 Cl LP K/S
|<ref>{{Cite journal|last1=Mazarico|first1=E.|last2=Lemoine|first2=F. G.|last3=Han|first3=Shin-Chan|last4=Smith|first4=D. E.|date=2010|title=GLGM-3: A degree-150 lunar gravity model from the historical tracking data of NASA Moon orbiters|journal=Journal of Geophysical Research|language=en|volume=115|issue=E5|pages=E05001, 1–14|doi=10.1029/2009JE003472|bibcode=2010JGRE..115.5001M|issn=0148-0227|doi-access=free}}</ref>
|-
|CEGM02
|100
|LO A15 A16 Cl LP K/S Ch1
|<ref>{{Cite journal|last1=Yan|first1=Jianguo|last2=Goossens|first2=Sander|last3=Matsumoto|first3=Koji|last4=Ping|first4=Jinsong|last5=Harada|first5=Yuji|last6=Iwata|first6=Takahiro|last7=Namiki|first7=Noriyuki|last8=Li|first8=Fei|last9=Tang|first9=Geshi|last10=Cao|first10=Jianfeng|last11=Hanada|first11=Hideo|display-authors=9|date=2012|title=CEGM02: An improved lunar gravity model using Chang'E-1 orbital tracking data|url=https://linkinghub.elsevier.com/retrieve/pii/S0032063311003382|journal=Planetary and Space Science|language=en|volume=62|issue=1|pages=1–9|doi=10.1016/j.pss.2011.11.010|bibcode=2012P&SS...62....1Y}}</ref>
|-
|GL0420A
|420
|G
|<ref>{{Cite journal|last1=Zuber|first1=M. T.|last2=Smith|first2=D. E.|last3=Neumann|first3=G. A.|last4=Goossens|first4=S.|last5=Andrews-Hanna|first5=J. C.|last6=Head|first6=J. W.|last7=Kiefer|first7=W. S.|last8=Asmar|first8=S. W.|last9=Konopliv|first9=A. S.|last10=Lemoine|first10=F. G.|last11=Matsuyama|first11=I.|display-authors=9|date=2016|title=Gravity field of the Orientale basin from the Gravity Recovery and Interior Laboratory Mission|journal=Science|language=en|volume=354|issue=6311|pages=438–441|doi=10.1126/science.aag0519|issn=0036-8075|pmc=7462089|pmid=27789835|bibcode=2016Sci...354..438Z}}</ref>
|-
|GL0660B
|660
|G
|<ref>{{Cite journal|last1=Konopliv|first1=Alex S.|last2=Park|first2=Ryan S.|last3=Yuan|first3=Dah-Ning|last4=Asmar|first4=Sami W.| last5=Watkins|first5=Michael M.| last6=Williams|first6=James G.|last7=Fahnestock|first7=Eugene| last8=Kruizinga|first8=Gerhard| last9=Paik|first9=Meegyeong| last10=Strekalov|first10=Dmitry|last11=Harvey|first11=Nate|display-authors=9|date=2013|title=The JPL lunar gravity field to spherical harmonic degree 660 from the GRAIL Primary Mission|url=http://doi.wiley.com/10.1002/jgre.20097|journal=Journal of Geophysical Research: Planets|language=en|volume=118|issue=7|pages=1415–1434|doi=10.1002/jgre.20097|bibcode=2013JGRE..118.1415K|hdl=1721.1/85858|s2cid=16559256 |hdl-access=free}}</ref>
|-
|GRGM660PRIM
|660
|G
|<ref name=":1" />
|-
|GL0900D
|900
|G
|<ref name=":0" />
|-
|GRGM900C
|900
|G
|<ref>{{Cite journal|last1=Lemoine|first1=Frank G.|last2=Goossens|first2=Sander|last3=Sabaka|first3=Terence J.|last4=Nicholas|first4=Joseph B.| last5=Mazarico|first5=Erwan|last6=Rowlands|first6=David D.|last7=Loomis|first7=Bryant D.|last8=Chinn|first8=Douglas S.|last9=Neumann|first9=Gregory A.| last10=Smith|first10=David E.|last11=Zuber|first11=Maria T.|date=2014|title=GRGM900C: A degree 900 lunar gravity model from GRAIL primary and extended mission data|journal=Geophysical Research Letters|language=en|volume=41|issue=10|pages=3382–3389|doi=10.1002/2014GL060027|issn=0094-8276|pmc=4459205|pmid=26074638|bibcode=2014GeoRL..41.3382L}}</ref>
|-
|GRGM1200A
|1200
|G
|<ref>{{Cite web|last1=Goossens|first1=Sander|last2=et|first2=al.|date=2016|title=A global degree and order 1200 model of the lunar gravity field using GRAIL mission data|url=https://www.hou.usra.edu/meetings/lpsc2016/pdf/1484.pdf}}</ref>
|-
|CEGM03
|100
|LO A15 A16 Cl LP Ch1 K/S Ch5T1
|<ref>{{Cite journal|last1=Yan|first1=Jianguo|last2=Liu|first2=Shanhong|last3=Xiao|first3=Chi|last4=Ye|first4=Mao|last5=Cao|first5=Jianfeng|last6=Harada|first6=Yuji|last7=Li|first7=Fei|last8=Li|first8=Xie|last9=Barriot|first9=Jean-Pierre|date=2020|title=A degree-100 lunar gravity model from the Chang'e 5T1 mission|journal=Astronomy & Astrophysics|volume=636|pages=A45, 1–11|doi=10.1051/0004-6361/201936802|bibcode=2020A&A...636A..45Y|s2cid=216482920 |issn=0004-6361|doi-access=free}}</ref>
|}
A major feature of the Moon's gravitational field is the presence of [[mass concentration (astronomy)|mascons]], which are large positive gravity anomalies associated with some of the giant [[impact crater|impact basins]]. These anomalies significantly influence the orbit of spacecraft around the Moon, and an accurate gravitational model is necessary in the planning of both crewed and uncrewed missions. They were initially discovered by the analysis of [[Lunar Orbiter]] tracking data:<ref>{{cite journal
 |author1=P. Muller |author2=W. Sjogren |date=1968
 |title=Mascons: Lunar mass concentrations
 |journal=[[Science (journal)|Science]]
 |volume=161 |issue=3842 |pages=680–84
 |bibcode = 1968Sci...161..680M
 |doi=10.1126/science.161.3842.680
 |pmid=17801458
|s2cid=40110502 }}</ref> navigation tests prior to the [[Apollo program]] showed positioning errors much larger than mission specifications.

Mascons are in part due to the presence of dense [[lunar mare|mare]] [[basalt]]ic [[lava|lava flows]] that fill some of the impact basins.<ref>{{cite journal | journal = Science | author = Richard A. Kerr | title = The Mystery of Our Moon's Gravitational Bumps Solved? | volume = 340 | issue = 6129 | pages = 138–39 | date = 12 April 2013 | doi=10.1126/science.340.6129.138-a | pmid=23580504}}</ref> However, lava flows by themselves cannot fully explain the gravitational variations, and uplift of the [[crust (geology)|crust]]-[[mantle (geology)|mantle]] interface is required as well. Based on [[Lunar Prospector]] gravitational models, it has been suggested that some mascons exist that do not show evidence for mare basaltic [[volcano|volcanism]].<ref name=":3">
{{cite journal
 |author1=A. Konopliv |author2=S. Asmar |author3=E. Carranza |author4=W. Sjogren |author5=D. Yuan |date=2001
 |title=Recent gravity models as a result of the Lunar Prospector mission
 |journal=[[Icarus (journal)|Icarus]]
 |volume=50 |issue=1 |pages=1–18
 |bibcode=2001Icar..150....1K
 |doi=10.1006/icar.2000.6573
|citeseerx=10.1.1.18.1930 }}</ref> The huge expanse of mare basaltic volcanism associated with [[Oceanus Procellarum]] does not cause a positive gravity anomaly. The center of gravity of the Moon does not coincide exactly with its geometric center, but is displaced toward the Earth by about 2 kilometers.<ref>[http://nineplanets.org/luna.html Nine Planets]</ref>
{{multiple image|align=center|total_width=600
|title=Moon – [[Oceanus Procellarum]] ("Ocean of Storms")
|width1=614 |height1=228 |image1=14-236-LunarGrailMission-OceanusProcellarum-Rifts-Overall-20141001.jpg|caption1=Ancient [[rift valley]]s – rectangular structure (visible – topography – [[Gravity Recovery and Interior Laboratory|GRAIL gravity gradients]]) (October 1, 2014).
|width2=1500  |height2=1500 |image2=PIA18822-LunarGrailMission-OceanusProcellarum-Rifts-Overall-20141001.jpg|caption2=Ancient [[rift valley]]s – context.
|width3=1546 |height3=905 |image3=PIA18821-LunarGrailMission-OceanusProcellarum-Rifts-Closeup-20141001.jpg|caption3=Ancient rift valleys – closeup (artist's concept).}}

== Mass of Moon ==
The [[gravitational constant]] ''G'' is less accurate than the product of ''G'' and masses for Earth and Moon.  Consequently, it is conventional to express the lunar mass ''M'' multiplied by the gravitational constant ''G''. The lunar ''GM'' = 4902.8001&nbsp;km<sup>3</sup>/s<sup>2</sup> from GRAIL analyses.<ref name=":0">{{Cite journal|last1=Konopliv|first1=Alex S.|last2=Park|first2=Ryan S.|last3=Yuan|first3=Dah-Ning|last4=Asmar|first4=Sami W.| last5=Watkins|first5=Michael M.|last6=Williams|first6=James G.|last7=Fahnestock|first7=Eugene| last8=Kruizinga|first8=Gerhard|last9=Paik|first9=Meegyeong| last10=Strekalov|first10=Dmitry|last11=Harvey|first11=Nate|date=2014|title=High-resolution lunar gravity fields from the GRAIL Primary and Extended Missions|journal=Geophysical Research Letters|language=en|volume=41|issue=5|pages=1452–1458|doi=10.1002/2013GL059066|bibcode=2014GeoRL..41.1452K|doi-access=free}}</ref><ref name=":1">{{Cite journal|last1=Lemoine|first1=Frank G.|last2=Goossens|first2=Sander|last3=Sabaka|first3=Terence J.|last4=Nicholas|first4=Joseph B.|last5=Mazarico|first5=Erwan|last6=Rowlands|first6=David D.|last7=Loomis|first7=Bryant D.|last8=Chinn|first8=Douglas S.|last9=Caprette|first9=Douglas S.|last10=Neumann|first10=Gregory A.|last11=Smith|first11=David E.|date=2013|title=High‒degree gravity models from GRAIL primary mission data|journal=Journal of Geophysical Research: Planets|language=en|volume=118|issue=8|pages=1676–1698|doi=10.1002/jgre.20118|bibcode=2013JGRE..118.1676L|issn=2169-9097|doi-access=free|hdl=2060/20140010292|hdl-access=free}}</ref><ref name=":2">{{Cite journal|last1=Williams|first1=James G.|last2=Konopliv|first2=Alexander S.|last3=Boggs|first3=Dale H.|last4=Park|first4=Ryan S.|last5=Yuan|first5=Dah-Ning|last6=Lemoine|first6=Frank G.|last7=Goossens|first7=Sander|last8=Mazarico|first8=Erwan|last9=Nimmo|first9=Francis|last10=Weber|first10=Renee C.|last11=Asmar|first11=Sami W.|date=2014|title=Lunar interior properties from the GRAIL mission|journal=Journal of Geophysical Research: Planets|language=en|volume=119|issue=7|pages=1546–1578|doi=10.1002/2013JE004559|bibcode=2014JGRE..119.1546W|s2cid=7045590 |doi-access=free}}</ref> The mass of the Moon is ''M'' = 7.3458 × 10<sup>22</sup>&nbsp;kg and the mean density is 3346&nbsp;kg/m<sup>3</sup>. The lunar ''GM'' is 1/81.30057 of the Earth's ''GM''.<ref>{{Cite journal|last1=Park|first1=Ryan S.|last2=Folkner|first2=William M.|last3=Williams|first3=James G.|last4=Boggs|first4=Dale H.|date=2021|title=The JPL Planetary and Lunar Ephemerides DE440 and DE441|journal=The Astronomical Journal|language=en|volume=161|issue=3|pages=105|doi=10.3847/1538-3881/abd414|bibcode=2021AJ....161..105P|s2cid=233943954|issn=1538-3881|doi-access=free}}</ref>

== Theory ==
For the lunar gravity field, it is conventional to use an equatorial radius of ''R'' = 1738.0&nbsp;km. The gravity potential is written with a series of spherical harmonic functions ''P''<sub>''nm''</sub>. The [[gravitational potential]] ''V'' at an external point is conventionally expressed as positive in astronomy and geophysics, but negative in physics. Then, with the former sign,

<math display="block">    V = \left ( \frac{GM}{r} \right )- \left ( \frac{GM}{r} \right ) \sum \left ( \frac{R}{r} \right )^n  J_n P_{n,0} (\sin \phi) + \left ( \frac{GM}{r} \right ) \sum \left ( \frac{R}{r} \right )^n [C_{n,m} P_{n,m}(\sin \phi) \cos(m \lambda) + S_{n,m}P_{n,m} (\sin \phi) \sin(m \lambda) ] </math>

where ''r'' is the radius to an external point with  r ≥ ''R'', ''φ'' is the latitude of the external point, and λ is the east longitude of the external point. Note that the spherical harmonic functions ''P<sub>nm</sub>'' can be normalized or unnormalized affecting the gravity coefficients ''J<sub>n</sub>'', ''C<sub>nm</sub>'', and ''S<sub>nm</sub>''. Here we will use unnormalized functions and compatible coefficients. The ''P<sub>n0</sub>'' are called [[Legendre polynomials|Legendre]] polynomials and the ''P<sub>nm</sub>'' with ''m''≠0 are called the [[Associated Legendre polynomials]], where subscript ''n'' is the degree, ''m'' is the order, and ''m'' ≤ ''n''. The sums start at ''n'' = 2. The unnormalized degree-2 functions are

<math display="block"> \begin{align}
P_{2,0} &= \frac{3}{2} \sin^2 \!\phi - \frac{1}{2} \\[1ex]
P_{2,1} &= 3 \sin \phi \cos \phi \\[1ex]
P_{2,2} &= 3 \cos^2 \phi
\end{align} </math>

Note that of the three functions, only ''P''<sub>20</sub>(±1)=1 is finite at the poles. More generally, only ''P''<sub>n0</sub>(±1)=1 are finite at the poles.

The gravitational acceleration of vector position '''r''' is

'''<math display="block">\begin{align}
\frac{d^2 r}{dt^2} &= \nabla V \\[1ex]
&= {\partial V \over \partial r} e_r + \frac{1}{r} {\partial V \over \partial \phi} e_\phi + \frac{1}{r \cos \phi} {\partial V \over \partial \lambda} {e_\lambda} 
\end{align}
</math>'''

where '''e<sub>r</sub>''', '''e'''<sub>φ</sub>, and '''e'''<sub>λ</sub> are unit vectors in the three directions.

== Gravity coefficients ==
The unnormalized gravity coefficients of degree 2 and 3 that were determined by the GRAIL mission are given in Table 1.<ref name=":0" /><ref name=":1" /><ref name=":2" /> The zero values of ''C''<sub>21</sub>, ''S''<sub>21</sub>, and ''S''<sub>22</sub> are because a principal axis frame is being used. There are no degree-1 coefficients when the three axes are centered on the center of mass. 
{| class="wikitable"
|+Lunar Gravity Coefficients
!''nm''
!''J''<sub>''n''</sub>
!''C''<sub>''nm''</sub>
!''S''<sub>''nm''</sub>
|-
|20
|203.3 × 10<sup>−6</sup>
|—
|—
|-
|21
|—
|0
|0
|-
|22
|—
|22.4 × 10<sup>−6</sup>
|0
|-
|30
|8.46 × 10<sup>−6</sup>
|—
|—
|-
|31
|—
|28.48 × 10<sup>−6</sup>
|5.89 × 10<sup>−6</sup>
|-
|32
|—
|4.84 × 10<sup>−6</sup>
|1.67 × 10<sup>−6</sup>
|-
|33
|—
|1.71 × 10<sup>−6</sup>
|<nowiki>−0.25 × 10</nowiki><sup>−6</sup>
|}
The ''J''<sub>2</sub> coefficient for an oblate shape to the gravity field is affected by rotation and solid-body tides whereas ''C''<sub>22</sub> is affected by solid-body tides. Both are larger than their equilibrium values showing that the upper layers of the Moon are strong enough to support elastic stress. The ''C''<sub>31</sub> coefficient is large.

=={{anchor|Simulating lunar gravity}}Simulating lunar gravity==
{{see also |Artificial gravity#Simulating lunar gravity}}
In January 2022 China was reported by the ''[[South China Morning Post]]'' to have built a small (60 [[centimeter]]s in [[diameter]]) research facility to simulate low lunar gravity with the help of [[magnet]]s.<ref name=Futurism01a>{{cite web |author=|authorlink=|title=China building "Artificial Moon" that simulates low gravity with magnets|url=https://futurism.com/the-byte/china-artificial-moon-magnets|website=Futurism.com|publisher=Recurrent Ventures|access-date=17 January 2022 |date=|language=|quote=Interestingly, the facility was partly inspired by previous research conducted by Russian physicist Andrew Geim in which he floated a frog with a magnet. The experiment earned Geim the Ig Nobel Prize in Physics, a satirical award given to unusual scientific research. It’s cool that a quirky experiment involving floating a frog could lead to something approaching an honest-to-God antigravity chamber.}}</ref><ref name=scmp2022-01-12a>{{cite web |author=Stephen Chen|authorlink=|title=China has built an artificial moon that simulates low-gravity conditions on Earth|url=https://www.scmp.com/news/china/science/article/3162972/china-has-built-artificial-moon-simulates-low-gravity-conditions|website=|publisher=[[South China Morning Post]]|access-date=17 January 2022 |date=12 January 2022 |language=|quote=It is said to be the first of its kind and could play a key role in the country’s future lunar missions. Landscape is supported by a magnetic field and was inspired by experiments to levitate a frog.}}</ref> The facility was reportedly partly inspired by the work of [[Andre Geim]] (who later shared the 2010 [[Nobel Prize in Physics]] for his research on [[graphene]]) and [[Michael Berry (physicist)|Michael Berry]], who both shared the [[Ig Nobel Prize]] in Physics in [[List of Ig Nobel Prize winners#2000|2000]] for the [[magnetic levitation]] of a frog.<ref name=Futurism01a/><ref name=scmp2022-01-12a/>

== See also ==
{{Portal|Solar System}}
* [[Magnetic field of the Moon]]
* [[Micro-g environment]]

== References ==
{{reflist}}
{{The Moon}}

[[Category:Geodesy]]
[[Category:Gravity|Moon]]
[[Category:Lunar science]]
[[Category:Gravimetry of objects]]