Themisto (moon)

Template:Short description Template:Use dmy dates {{#invoke:infobox|infoboxTemplate | class = vcard | titleclass = fn org | title = Themisto | image = {{#invoke:InfoboxImage|InfoboxImage|image=S 2000 J 1.jpg|upright={{#if:||1.1}}|alt=}} | caption = Rediscovery images of Themisto taken by the UH88 telescope in November 2000 | headerstyle = {{#if:|background-color:|background-color:#E0CCFF}} | labelstyle = max-width:{{#if:||11em}}; | autoheaders = y

| header1 = Discovery<ref name="IAUC2845"/><ref name="IAUC7525"/>

| label2 = Discovered by | data2 = Charles T. Kowal Template:Small
Elizabeth P. Roemer Template:Small
Scott S. Sheppard Template:Small
David C. Jewitt Template:Small
Yanga R. Fernández Template:Small
Eugene A. Magnier Template:Small | label3 = Discovery site | data3 = Palomar Observatory
Mauna Kea Observatory Template:Small | label4 = Discovery date | data4 = 30 September 1975
21 November 2000 Template:Small | label5 = Template:Longitem | data5 =

| header10 = {{#if:|Designations|Designations}}

| label11 = Template:Longitem | data11 = Jupiter XVIII | label12 = Pronunciation | data12 = Template:IPAc-en<ref>Cf. 'Themista' in Template:Cite book</ref> | label13 = Template:Longitem | data13 = Θεμιστώ Themistō | label14 = Template:Longitem | data14 = S/2000 J 1
S/1975 J 1 | label15 = Template:Longitem | data15 = | label16 = Adjectives | data16 = Themistoan Template:IPAc-en<ref>'Themis[t]oan' in Template:Cite book</ref> Template:Nowrap | label17 = Symbol | data17 =

| header20 = Orbital characteristics{{#ifeq:|yes| (barycentric)}}<ref name="MPC110499"/>

| data21 = | data22 = {{#if:23 March 2018 (JD 2458200.5) |Epoch 23 March 2018 (JD 2458200.5)}} | data23 = {{#if: | Uncertainty parameter {{{uncertainty}}}}} | label24 = Observation arc | data24 = 42.54 yr (15,536 days) | label25 = Earliest precovery date | data25 = | label26 = {{#switch:{{{apsis}}} |apsis|gee|barion|center|centre|(apsis)=Apo{{{apsis}}} |Ap{{#if:|{{{apsis}}}|helion}}}} | data26 = | label27 = Peri{{#if:|{{{apsis}}}|helion}} | data27 = | label28 = Peri{{#if:|{{{apsis}}}|apsis}} | data28 = | label29 = {{#switch:{{{apsis}}} |helion|astron=Ap{{{apsis}}} |Apo{{#if:|{{{apsis}}}|apsis}}}} | data29 = | label30 = Periastron | data30 = | label31 = Apoastron | data31 = | label32 = Template:Longitem | data32 = Template:Cvt | label33 = Template:Longitem | data33 = | label34 = Eccentricity | data34 = 0.2522112 | label35 = Template:Longitem | data35 = +129.95 d | label36 = Template:Longitem | data36 = | label37 = Template:Longitem | data37 = | label38 = Template:Longitem | data38 = 2.39396° | label39 = Template:Longitem | data39 = Template:Deg2DMS / day | label40 = Inclination | data40 = 45.28121° (to ecliptic) | label41 = Template:Longitem | data41 = | label42 = Template:Longitem | data42 = 192.64162° | label43 = Template:Longitem | data43 = | label44 = Template:Longitem | data44 = | label45 = Template:Longitem | data45 = 241.25168° | label46 = Template:Nowrap | data46 = | label47 = Satellite of | data47 = Jupiter | label48 = Group | data48 = (own group) | label49 = {{#switch: |yes|true=Satellites |Known satellites}} | data49 = | label50 = Star | data50 = | label51 = Earth MOID | data51 = | label52 = Mercury MOID | data52 = | label53 = Venus MOID | data53 = | label54 = Mars MOID | data54 = | label55 = Jupiter MOID | data55 = | label56 = Saturn MOID | data56 = | label57 = Uranus MOID | data57 = | label58 = Neptune MOID | data58 = | label59 = T_Jupiter | data59 =

| header60 = Proper orbital elements

| label61 = Template:Longitem | data61 = {{#if: |{{{p_semimajor}}} AU}} | label62 = Template:Longitem | data62 = | label63 = Template:Longitem | data63 = | label64 = Template:Longitem | data64 = {{#if: |{{{p_mean_motion}}} degTemplate:\yr}} | label65 = Template:Longitem | data65 = {{#if:|{{#expr:360/1 round 5}} yr
({{#expr:365.25*360/1 round 3}} d) }} | label66 = Template:Longitem | data66 = {{#if:|{{{perihelion_rate}}} arcsecTemplate:\yr }} | label67 = Template:Longitem | data67 = {{#if:|{{{node_rate}}} arcsecTemplate:\yr}}

| header70 = Template:Anchor{{#if:| Physical characteristics|Physical characteristics}}

| label71 = Dimensions | data71 = | label72 = Template:Longitem | data72 = 9 km<ref name="SheppardMoons"/>
16.4 km<ref name="EmelyanovEtAl2022"/> | label73 = Template:Longitem | data73 = | label74 = Template:Longitem | data74 = | label75 = Template:Longitem | data75 = | label76 = Flattening | data76 = | label77 = Circumference | data77 = | label78 = Template:Longitem | data78 = | label79 = Volume | data79 = | label80 = Mass | data80 = | label81 = Template:Longitem | data81 = | label82 = Template:Longitem | data82 = | label83 = Template:Longitem | data83 = | label84 = Template:Longitem | data84 = | label85 = Template:Longitem | data85 = | label86 = Template:Longitem | data86 = | label87 = Template:Longitem | data87 = | label88 = Template:Longitem | data88 = | label89 = Template:Longitem | data89 = | label90 = Template:Longitem | data90 = | label91 = Template:Longitem | data91 = | label92 = Template:Longitem | data92 = | label93 = {{#if: |Template:Longitem |Albedo}} | data93 = 0.04 (assumed) | label94 = Temperature | data94 =

| data100 = {{#if:|

{{#if:|}}{{#if:|}}{{#if:|}}{{#if:|}}

Surface temp.	min	mean	max
{{{temp_name1}}}
{{{temp_name2}}}
{{{temp_name3}}}
{{{temp_name4}}}

}}

| label101 = Surface absorbed dose rate | data101 = | label102 = Surface equivalent dose rate | data102 = | label103 = Template:Longitem | data103 = | label104 = Template:Longitem | data104 = | label105 = Template:Longitem | data105 = 21.0<ref name="SheppardMoons"/> | label106 = Template:Longitem | data106 = 12.9<ref name="MPC110499"/>
Template:Val (V)<ref name="EmelyanovEtAl2022"/> | label107 = Template:Longitem | data107 =

| header110 = Atmosphere

| label111 = Template:Longitem | data111 = | label112 = Template:Longitem | data112 = | label113 = Composition by volume | data113 =

| below = {{#if:||Template:Reflist }}

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Themisto (Template:IPAc-en), also known as Template:Nowrap, is a small prograde irregular satellite of Jupiter. It was discovered in 1975, subsequently lost, and rediscovered in 2000.

Discovery and naming

File:Themisto-Holman-CFHT.gif

Themisto observed by the Canada–France–Hawaii Telescope on 6Template:NbspAugust 2000, several months before its rediscovery in November 2000

Themisto was first discovered by Charles T. Kowal and Elizabeth Roemer on 30Template:NbspSeptember 1975, reported on 3Template:NbspOctober 1975,<ref name="IAUC2845">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and designated Template:Nowrap. However, not enough observations were made to establish an orbit and it was subsequently lost.

Then, on 21Template:NbspNovember 2000, a seemingly new satellite was discovered by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernández and Eugene A. Magnier and was designated Template:Nowrap. It was soon confirmed from computing the past trajectory of the satellite that this was the same as the one observed in 1975.<ref name="IAUC7525">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This observation was immediately correlated with an earlier observation on 6Template:NbspAugust 2000 by the team of Brett J. Gladman, John J. Kavelaars, Jean-Marc Petit, Hans Scholl, Matthew J. Holman, Brian G. Marsden, Philip D. Nicholson and Joseph A. Burns, which was reported to the Minor Planet Center but not published as an IAU Circular (IAUC).<ref name="MPEC-2000-Y16">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In October 2002, it was officially named after Themisto,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> daughter of the river god Inachus and lover of Zeus (Jupiter) in Greek mythology.

Characteristics

File:TheIrregulars JUPITER GROUPS.svg

Diagram illustrating Themisto's orbit (top left) among those of the other irregular satellites of Jupiter. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the orbital eccentricity.

Themisto's orbit is unusual: unlike most of Jupiter's moons, which orbit in distinct groups, Themisto orbits alone. The moon is located midway between the Galilean moons and the first group of prograde irregular moons, the Himalia group.

Themisto is about Template:Cvt in diameter (assuming an albedo of 0.04).<ref name="SheppardMoons"/> While its true albedo could not be measured by NEOWISE due to poor timing of observations,<ref name="Grav2015">Template:Cite journal</ref> it is known to have color index B−V=0.83, V−R=0.46, and V−I=0.94.<ref name="Grav2003">Template:Cite journal</ref>

External links

• David Jewitt's pages
• Jupiter's Known Satellites Template:Webarchive (by Scott S. Sheppard)
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