Galatea (moon)
Template:Short description Template:For {{#invoke:infobox|infoboxTemplate | class = vcard | titleclass = fn org | title = Galatea | image = {{#invoke:InfoboxImage|InfoboxImage|image=Galatea moon.jpg|upright={{#if:||1.1}}|alt=}} | caption = Galatea as seen by Voyager 2 (elongation is due to smearing) | headerstyle = {{#if:|background-color:|background-color:#E0CCFF}}; color:inherit; | labelstyle = max-width:{{#if:||11em}}; | autoheaders = y
| header1 = Discovery
| label2 = Discovered by | data2 = Stephen P. Synnott<ref name="Willman-Neptune" /> and Voyager Imaging Team | label3 = Discovery site | data3 = | label4 = Discovery date | data4 = July 1989 | label5 = Template:Longitem | data5 =
| header10 = {{#if:|Designations|Designations}}
| label11 = Template:Longitem | data11 = Neptune VI | label12 = Pronunciation | data12 = Template:IPAc-en<ref>Template:OED</ref> | label13 = Template:Longitem | data13 = Γαλάτεια Galateia | label14 = Template:Longitem | data14 = | label15 = Template:Longitem | data15 = | label16 = Adjectives | data16 = Galatean<ref>Template:Citation</ref> | label17 = Symbol | data17 =
| header20 = Orbital characteristics{{#ifeq:|yes| (barycentric)}}<ref name="Jacobson2004" /><ref name="Showalter2019" />
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| header60 = Proper orbital elements
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({{#expr:365.25*360/1 round 3}} d) }}
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| header70 = Template:Anchor{{#if:| Physical characteristics|Physical characteristics}}
| label71 = Dimensions
| data71 = (Template:Val) × (Template:Val) × (Template:Val) km<ref name="Karkoschka2003" />
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| data73 = Template:Val<ref name="Karkoschka2003" />
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| label76 = Flattening
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| label77 = Circumference
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| label79 = Volume
| data79 = ~Template:Val<ref name="Volume" group="lower-alpha" />
| label80 = Mass
| data80 = Template:Val<ref>Giuliatti Winter et al. (2020), as cited in Madeira & Giuliatti Winter (2022).<ref name="Madeira & GiuliattiWinter 2022"/></ref>
Template:Val<ref name="Porco1991" />
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| data85 = synchronous
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| data88 = zero
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| label93 = {{#if: |Template:Longitem |Albedo}}
| data93 = 0.08<ref name="Karkoschka2003" /><ref name="jplssd" />
| label94 = Temperature
| data94 = ~51 K mean (estimate)
| data100 = {{#if:|
{{#if:|}}{{#if:|}}{{#if:|}}{{#if:|}}| Surface temp. | min | mean | max |
|---|---|---|---|
| {{{temp_name1}}} | |||
| {{{temp_name2}}} | |||
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| {{{temp_name4}}} |
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| label101 = Surface absorbed dose rate | data101 = | label102 = Surface equivalent dose rate | data102 = | label103 = Template:Longitem | data103 = | label104 = Template:Longitem | data104 = | label105 = Template:Longitem | data105 = 21.9<ref name="jplssd" /> | label106 = Template:Longitem | data106 = | label107 = Template:Longitem | data107 =
| header110 = Atmosphere
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Galatea Template:IPAc-en, also known as Neptune VI, is the fourth-closest inner moon of Neptune, and fifth-largest moon of Neptune. It is named after Galatea, one of the fifty Nereids of Greek legend, with whom Cyclops Polyphemus was vainly in love.
Discovery
Galatea was discovered in late July 1989 from the images taken by the Voyager 2 probe. It was given the temporary designation S/1989 N 4.<ref name="IAUC 4824" /> The discovery was announced (IAUC 4824) on 2 August 1989, and mentions "10 frames taken over 5 days", implying a discovery date of sometime before July 28. The name was given on 16 September 1991.<ref name="IAUC 5347" />
Physical properties
Galatea is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were smashed up by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit.<ref name="BanfieldMurray1992" />
Compositionally, Galatea appears to be similar to other small inner Neptunian satellites, with a deep 3.0 micron feature attributed to water ice or hydrated silicate minerals. It has a 0.08 albedo at 1.4 and 2.0 microns, dropping to 0.04 at 3.0 microns, and increasing to 0.12 at 4.6 microns.<ref>Template:Cite journal</ref>
Orbit
Galatea's orbit lies below Neptune's synchronous orbit radius, so it is slowly spiralling inward due to tidal deceleration and may eventually impact the planet or break up into a new planetary ring system upon passing its Roche limit due to tidal stretching.
Galatea appears to be a shepherd moon for the Adams ring that is Template:Convert outside its orbit. Resonances with Galatea in the ratio 42:43 are also considered the most likely mechanism for confining the unique ring arcs that exist in this ring.<ref name="NamouniPorco" /> Galatea's mass has been estimated based on the radial perturbations it induces on the ring.<ref name="Madeira & GiuliattiWinter 2022"/><ref name="Porco1991" />
Notes
References
External links
- Galatea Profile by NASA's Solar System Exploration
- Neptune's Known Satellites (by Scott S. Sheppard)
{{#invoke:Navbox|navbox}} Template:Solar System moons (compact) Template:Neptune