Cressida (moon)

There is also an asteroid called 548 Kressida.

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| header1 = Discovery

| label2 = Discovered by | data2 = Stephen P. Synnott / Voyager 2 | label3 = Discovery site | data3 = | label4 = Discovery date | data4 = January 9, 1986 | label5 = Template:Longitem | data5 =

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

| label11 = Template:Longitem | data11 = Uranus IX | label12 = Pronunciation | data12 = Template:IPAc-en<ref>Template:Cite book</ref> | label13 = Template:Longitem | data13 = Χρησίδα | label14 = Template:Longitem | data14 = | label15 = Template:Longitem | data15 = | label16 = Adjectives | data16 = Cressidian Template:IPAc-en<ref>Template:Cite book</ref> | label17 = Symbol | data17 =

| header20 = Orbital characteristics{{#ifeq:|yes| (barycentric)}}<ref name="Jacobson 1998" />

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| header60 = Proper orbital elements

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({{#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 = 92 × 74 × 74 km<ref name="Karkoschka, Voyager 2001" />Template:Refn | label72 = Template:Longitem | data72 = | label73 = Template:Longitem | data73 = | label74 = Template:Longitem | data74 = | label75 = Template:Longitem | data75 = | label76 = Flattening | data76 = | label77 = Circumference | data77 = | label78 = Template:Longitem | data78 = ~Template:ValTemplate:Efn | label79 = Volume | data79 = Template:Val<ref name = "FrenchEtAl2024"/> | label80 = Mass | data80 = Template:Val<ref name = "FrenchEtAl2024"/> | label81 = Template:Longitem | data81 = Template:Val<ref name = "FrenchEtAl2024"/> | label82 = Template:Longitem | data82 = ~Template:Gr–Template:Gr m/s²Template:Efn | label83 = Template:Longitem | data83 = | label84 = Template:Longitem | data84 = ~Template:V2–Template:V2 km/sTemplate:Efn | label85 = Template:Longitem | data85 = synchronous<ref name="Karkoschka, Voyager 2001" /> | label86 = Template:Longitem | data86 = | label87 = Template:Longitem | data87 = | label88 = Template:Longitem | data88 = zero<ref name="Karkoschka, Voyager 2001" /> | 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="Karkoschka, Hubble 2001" />
0.07<ref name="Williams 2007 nssdc" /> | label94 = Temperature | data94 = ~65 KTemplate:Efn

| data100 = {{#if:|

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| header110 = Atmosphere

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Cressida Template:IPAc-en is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 9 January 1986, and was given the temporary designation S/1986 U 3.<ref name="IAUC 4164" /> It was named after Cressida, the Trojan daughter of Calchas, a tragic heroine who appears in William Shakespeare's play Troilus and Cressida (as well as in tales by Geoffrey Chaucer and others). It is also designated Uranus IX.<ref name="Gazetteer" />

Cressida belongs to the Portia group of satellites, which includes Bianca, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda, and Perdita.<ref name="Karkoschka, Hubble 2001" /> These satellites have similar orbits and photometric properties.<ref name="Karkoschka, Hubble 2001" /> Other than its orbit,<ref name="Jacobson 1998" /> size of 92 × 74 km,<ref name="Karkoschka, Voyager 2001" /> and geometric albedo of 0.08,<ref name="Karkoschka, Hubble 2001" /> virtually nothing is known about it.

In Voyager 2 imagery Cressida appears as an elongated object, with its major axis pointing towards Uranus. The ratio of axes of Cressida's prolate spheroid is 0.8 ± 0.3.<ref name="Karkoschka, Voyager 2001" /> Its surface is grey in color.<ref name="Karkoschka, Voyager 2001" />

Cressida orbits close to a 3:2 resonance with the η ring, one of the rings of Uranus. Perturbations of the ring's shape provide a way to measure the mass of Cressida, which in 2024 was found to be Template:Val.<ref name = "FrenchEtAl2024"/> Cressida is one of the few small satellites of Uranus for which the mass has been directly measured.<ref name="Eta-ring" /><ref name = "FrenchEtAl2024"/>

Cressida may collide with Desdemona within the next 100 million years.<ref name="Duncan Lissauer 1997" />

See also

• Moons of Uranus

External links

• Cressida Profile by NASA's Solar System Exploration
• Uranus' Known Satellites (by Scott S. Sheppard)

Template:Uranus {{#invoke:Navbox|navbox}} Template:Solar System moons (compact)