Perdita (moon)

{{Short description|Moon of Uranus}}

{{Infobox planet

| name = Perdita

| image = Perdita feat.jpg

| image_scale = 1.5

| caption =

| mpc_name = Uranus XXV

| pronounced = {{IPAc-en|ˈ|p|ɜːr|d|ə|t|ə}}{{cite book|author=Benjamin Smith|year=1903|title=The Century Dictionary and Cyclopedia}}

| adjective = Perditean {{IPAc-en|p|ɜːr|d|ə|ˈ|t|iː|ə|n}}{{cite book|last=Byrne|year=2008|title=Perdita: the literary, theatrical, scandalous life of Mary Robinson}}J. B. Lethbridge (2013) Shakespeare and Spenser: Attractive opposites.

| discoverer = Erich Karkoschka / Voyager 2

| discovered = May 18, 1999 (in images dating back to January 18, 1986)

| mean_orbit_radius = 76,417 ± 1 km{{sfn|Karkoschka, Voyager|2001}}

| eccentricity = 0.0012 ± 0.0005{{sfn|Karkoschka, Voyager|2001}}

| period = 0.638021 ± 0.000013 d{{sfn|Karkoschka, Voyager|2001}}

| inclination = 0.0 ± 0.3° (to Uranus's equator){{sfn|Karkoschka, Voyager|2001}}

| satellite_of = Uranus

| mean_radius = {{val|13.3|0.7|u=km}}{{refn|name=radius}}

| surface_area = ~{{val|2200|u=km2}}{{efn|name=calculated}}

| volume = ~{{val|9900|u=km3}}{{efn|name=calculated}}

| mass = ~{{val|4.9|-|12|e=15|u=kg}}{{efn|name=calculated}}

| density = 0.5{{sfn|French|Showalter|2012}}–1.2{{sfn|French|Showalter|2012}}{{sfn|Ćuk et al.|2022}} g/cm{{sup|3}}

| surface_grav = ~{{Gr|4.93e-6|13.3}}–{{Gr|11.8e-6|13.3}} m/s²{{efn|name=calculated}}

| escape_velocity = ~{{V2|4.93e-6|13.3}}–{{V2|11.8e-6|13.3}} km/s{{efn|name=calculated}}

| rotation = synchronous{{sfn|Karkoschka, Voyager|2001}}

| axial_tilt = zero{{sfn|Karkoschka, Voyager|2001}}

| albedo = 0.08 ± 0.01 (assumed){{sfn|Showalter|Lissauer|2006}}

| single_temperature = ~64 K{{efn|name=calculated}}

}}

Perdita {{IPAc-en|ˈ|p|ɜːr|d|ə|t|ə}} is an inner satellite of Uranus. Perdita's discovery was very complicated, as the first photographs of Perdita were taken by the Voyager 2 spacecraft in 1986, but it was not recognized from the photographs for more than a decade. In 1999, the moon was noticed by Erich Karkoschka and reported.{{sfn|Karkoschka, Voyager|2001}}{{sfn|IAUC 7171}} But because no further pictures could be taken to confirm its existence, it was officially demoted in 2001.{{sfn|Foust|2001}} However, in 2003, pictures taken by the Hubble Space Telescope managed to pick up an object where Perdita was supposed to be, finally confirming its existence.{{sfn|Showalter|Lissauer|2006}}{{sfn|IAUC 8194}}

Following its discovery in 1999, it was given the temporary designation of S/1986 U 10.{{sfn|IAUC 7171}} It was named Perdita (Latin for 'lost') after the daughter of Leontes and Hermione in William Shakespeare's play The Winter's Tale. The moon is also designated Uranus XXV.{{sfn|USGS: Planet and Satellite Names and Discoverers}}

File:Uranus' Satellite 1986 U10 Discovery Image.jpg

The moon orbits between Belinda and Puck. The above-mentioned Hubble measurements prove that Perdita does not follow a direct Keplerian motion around Uranus. Instead, it is clearly caught in a 43:44 orbital resonance with the nearby moon Belinda, and from this resonance it has been determined that Belinda's mass is 26{{Cite conference |last=French |first=Robert S. |last2=Showalter |first2=Mark R. |last3=de Pater |first3=Imke |last4=Lissauer |first4=Jack J. |date=2017-10-01 |title=Orbital and Photometric Analysis of the Inner Uranian Satellites from Hubble Images |url=https://ui.adsabs.harvard.edu/abs/2017DPS....4921419F |volume=49 |pages=214.19}} or 27{{sfn|Ćuk et al.|2022}} times that of Perdita. It is also close to an 8:7 resonance with Rosalind.{{sfn|Karkoschka, Voyager|2001}}{{sfn|Showalter|Lissauer|2006}}

Perdita belongs to the Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind, and Belinda.{{sfn|Karkoschka, Hubble|2001}} These satellites have similar orbits and photometric properties.{{sfn|Karkoschka, Hubble|2001}} Little is known about Perdita apart from its orbit,{{sfn|Karkoschka, Voyager|2001}}{{sfn|Showalter|Lissauer|2006}} radius of 13.3 km,{{refn|name=radius|Showalter & Lissauer (2006),{{sfn|Showalter|Lissauer|2006}} as cited in Ćuk et al. (2022).{{sfn|Ćuk et al.|2022}}}} and geometric albedo of 0.08.{{sfn|Karkoschka, Hubble|2001}}{{sfn|Showalter|Lissauer|2006}}