Elara (moon)

Template:Short description Template:Use dmy dates {{#invoke:infobox|infoboxTemplate | class = vcard | titleclass = fn org | title = Elara | image = {{#invoke:InfoboxImage|InfoboxImage|image=File:Elara - New Horizons.png|upright={{#if:||1.1}}|alt=}} | caption = Low-resolution image of Elara from the New Horizons probe, March 2007 | headerstyle = {{#if:|background-color:|background-color:#E0CCFF}} | labelstyle = max-width:{{#if:||11em}}; | autoheaders = y

| header1 = Discovery <ref name="Harvard1905"/><ref name="Perrine1905"/>

| label2 = Discovered by | data2 = Charles D. Perrine | label3 = Discovery site | data3 = Lick Observatory | label4 = Discovery date | data4 = 5 January 1905 | label5 = Template:Longitem | data5 =

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

| label11 = Template:Longitem | data11 = Jupiter VII | label12 = Pronunciation | data12 = Template:IPAc-en<ref>James Knowles (1851) A Critical Pronouncing Dictionary of the English Language</ref> | label13 = Template:Longitem | data13 = Ελάρα Elăra<ref>DGE en línea</ref> | label14 = Template:Longitem | data14 = | label15 = Template:Longitem | data15 = | label16 = Adjectives | data16 = Elarian Template:IPAc-en | label17 = Symbol | data17 =

| header20 = Orbital characteristics{{#ifeq:|yes| (barycentric)}} <ref name="MPC115889"/>

| data21 = | data22 = {{#if:27 April 2019 (JD 2458600.5) |Epoch 27 April 2019 (JD 2458600.5)}} | data23 = {{#if: | Uncertainty parameter {{{uncertainty}}}}} | label24 = Observation arc | data24 = 113.70 yr (41,528 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 = 0.1961487 | label35 = Template:Longitem | data35 = +258.65 d | label36 = Template:Longitem | data36 = | label37 = Template:Longitem | data37 = | label38 = Template:Longitem | data38 = 10.93078° | label39 = Template:Longitem | data39 = Template:Deg2DMS / day | label40 = Inclination | data40 = 30.51712° (to ecliptic) | label41 = Template:Longitem | data41 = | label42 = Template:Longitem | data42 = 90.86474° | label43 = Template:Longitem | data43 = | label44 = Template:Longitem | data44 = | label45 = Template:Longitem | data45 = 191.19922° | label46 = Template:Nowrap | data46 = | label47 = Satellite of | data47 = Jupiter | label48 = Group | data48 = Himalia 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 = Template:Val<ref name="Grav2015"/> | 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 = Template:Val<ref name="Grav2015"/> | 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 = 16.6<ref name="SheppardMoons"/> | label106 = Template:Longitem | data106 = 9.6<ref name="MPC115889"/> | label107 = Template:Longitem | data107 =

| header110 = Atmosphere

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

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

}}{{#invoke:Check for unknown parameters|check|unknown=Template:Main other|preview=Page using Template:Infobox planet with unknown parameter "_VALUE_"|ignoreblank=y| abs_magnitude | adjective | adjectives | albedo | allsatellites | alt_names | angular_dist | angular_size | aphelion | apoapsis | apsis | apoastron | arg_peri | asc_node | atmosphere | atmosphere_composition | atmosphere_ref | avg_speed | axial_tilt | background | barycentric | bgcolour | caption | circumference | declination | density | dimensions | discovered | discoverer | discovery_method | discovery_ref | discovery_site | earliest_precovery_date | eccentricity | epoch | equatorial_radius | escape_velocity | exosolar planets | extrasolarplanet | family | flattening | group | image | image_alt | image_scale | inclination | jupiter_moid | label_width | long_periastron | magnitude | mars_moid | mass | max_temp_1 | max_temp_2 | max_temp_3 | max_temp_4 | mean_anomaly | mean_diameter | mean_motion | mean_orbit_radius | mean_radius | mean_temp_1 | mean_temp_2 | mean_temp_3 | mean_temp_4 | mercury_moid | min_temp_1 | min_temp_2 | min_temp_3 | min_temp_4 | minorplanet | moid | moment_of_inertia_factor | mp_category | mp_name | mpc_name | name | named_after | neptune_moid | node_rate | note | observation_arc | orbit_diagram | orbit_ref | p_eccentricity | p_inclination | p_mean_motion | p_orbit_ref | p_semimajor | periapsis | periastron | perihelion | perihelion_rate | period | physical_ref | polar_radius | pole_ecliptic_lat | pole_ecliptic_lon | pronounce | pronounced | right_asc_north_pole | rot_velocity | rotation | satellite_of | satellites | saturn_moid | scale_height | semi-amplitude | semimajor | sidereal_day | single_temperature | spectral_type | star | surface_area | surface_grav | surface_pressure | surface_absorbed_dose_rate | surface_equivalent_dose_rate | symbol | synodic_period | temp_name1 | temp_name2 | temp_name3 | temp_name4 | time_periastron | tisserand | uncertainty | uranus_moid | venus_moid | volume }}

Elara Template:IPAc-en is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905 in photographs taken with the 36" Crossley reflecting telescope which he had recently rebuilt.<ref name="Harvard1905"/><ref name="Perrine 1905"/> It is the eighth-largest moon of Jupiter and is named after Elara, one of Zeus's lovers and the mother of the giant Tityos.<ref name="IAUC 2846">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Elara did not receive its present name until 1975; before then, it was simply known as Template:Nowrap. It was sometimes called "Hera"<ref name="Gaposchkin">Template:Cite book</ref> between 1955 and 1975. It has a mean radius of just Template:Convert, thus it is 2% of the size of Europa. However, it is half the size of Himalia, so it is the second-biggest moon in the Himalia group. It might be a captured type C or D asteroid, for it reflects very little light.

Elara belongs to the Himalia group, moons orbiting between 11 and 13 gigametres from Jupiter at an inclination of about 27.5°.<ref name="Jacobson 2000">Template:Cite journal</ref> Its orbital elements are as of January 2000. They are continuously changing due to solar and planetary perturbations.

Discovery

Elara was discovered by Charles Dillon Perrine of the Lick Observatory on January 6, 1905, the day after the discovery of Himalia, also by Perrine, was announced. However, poor weather conditions delayed the confirmation of the discovery till the 21st of February.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Exploration

New Horizons encounter

In February and March 2007, the New Horizons spacecraft to Pluto captured Elara in several LORRI images from a distance of five million miles.<ref>Template:Cite book</ref>

See also

• Jupiter's moons in fiction

External links

• Elara on 1998-08-15 03:21 UTC(Crédit: OHP/IMCCE/CNRS)
• SkyView 23 47 09 -02 40 46
• HORIZONS Web-Interface, JPL
• Elara: Overview by NASA's Solar System Exploration
• David Jewitt pages
• "Two Irregular Satellites of Jupiter" (Himalia & Elara: Remanzacco Observatory: November 23, 2012)