查看“︁天卫二”︁的源代码

{{NoteTA
|G1=Astronomy
|G2=Physics
}}
{{Infobox planet
| name               = 烏姆柏里厄爾
| alt_names          = 
| mpc_name           = 天卫二
| pronounced         = {{IPAc-en|ˈ|ʌ|m|b|r|i|ə|l}}<ref name="dict-def" />
| adjectives         = Umbrielian
| image              = PIA00040 Umbrielx2.47.jpg
| image_size         = 260px
| image_alt          = A round spherical body with its left half illuminated. The surface is dark and has a low contrast. There are only a few bright patches. The terminator is slightly to the right from the center and runs from the top to bottom. A large crater with a bright ring on its floor can be seen at the top of the image near the terminator. A pair of large craters with bright central peaks can be seen along the terminator in the upper part of the body. The illuminated surface is covered by a large number of craters.
| caption            =當[[航海家二號]]於1986年經過天王星時，拍下的天衛二。
| discoverer         = [[威廉·拉塞尔]]
| discovered         = 1851年10月24日
| orbit_ref          =<ref name="orbit" />
| semimajor          = {{val|266000|u=km}}
| eccentricity       = {{val|0.0039}}
| period             = {{val|4.144|u=天}}
| avg_speed          = 4.67 km/s (calculated)
| inclination        = {{val|0.128|u=°}} (到天王星的赤道)
| satellite_of       = [[天王星]]
| mean_radius        = {{val|584.7|2.8|u=km}} (0.092顆地球)<ref name="Thomas 1988" />
| surface_area       = {{val|4296000|u=km2}} (0.008顆地球){{註|name=surface area|Surface area derived from the radius ''r'' : <math>4\pi r^2</math>.}}
| volume             = {{val|837300000|u=km3}} (0.0008顆地球){{註|name=volume|Volume ''v'' derived from the radius ''r'' : <math>4\pi r^3/3</math>.}}
| mass               = {{val|1.275|0.028|e=21|u=kg}}<ref name="Jacobson 2014">R. A. Jacobson (2014) 'The Orbits of the Uranian Satellites and Rings, the Gravity Field of the Uranian System, and the Orientation of the Pole of Uranus'. ''The Astronomical Journal'' 148:5</ref>
| density            = {{val|1.39|0.16|u=g/cm3}}<ref name="Jacobson Campbell et al. 1992" />
| surface_grav       = {{Gr|1.275|584.7|2}} [[加速度|m/s<sup>2</sup>]] (~&nbsp;0.023 [[G力|g]]){{註|name=surface gravity|Surface gravity derived from the mass ''m'', the [[萬有引力常數]] ''G'' and the radius ''r'' : <math>Gm/r^2</math>.}}
| escape_velocity    = {{V2|1.275|584.7|2}} km/s{{註|name=escape velocity|Escape velocity derived from the mass ''m'', the [[萬有引力常數]] ''G'' and the radius ''r'' : <math>\sqrt{\frac{2Gm}{r} }</math>.}}
| rotation           =[[潮汐鎖定]]（假定）<ref name="Smith Soderblom et al. 1986" />
| axial_tilt         = 0<ref name="Smith Soderblom et al. 1986" />
| albedo =
{{plainlist |
* 0.26 (几何)
* 0.10 (纽带)<ref name="Karkoschka 2001, Hubble" />
}}
| magnitude          = 14.5 (V-band, opposition)<ref name="NASAspp" />
| temp_name1         = solstice<ref name="Grundy Young et al. 2006" />
| mean_temp_1        = ≈&thinsp;75&nbsp;[[克耳文|K]]
| max_temp_1         = 85&nbsp;K
| min_temp_1         = ?
| atmosphere         = no
| surface_pressure   = zero (presumed to be extremely low)
| note               = no
}}
'''天卫二'''（'''烏姆柏里厄爾'''，{{lang-en|Umbriel}}，[[國際音標|国际音标]]：[ˈʌmbɹiəl]<ref name="US dict-def" />）是[[天王星]]的[[衛星]]，以[[亚历山大·蒲柏|亞歷山大·蒲柏]]的作品《{{link-en|秀髮劫|The_Rape_of_the_Lock}}》裡的角色烏姆柏里厄爾命名<ref name="Kuiper 1949" />。它與[[天衛一]]同時由[[威廉·拉塞尔]]在1851年10月24日發現。<ref name=UMoons />天卫二的直徑比天衛一大10公里，但密度相同。<ref name="fd9000" /> 天卫二主要由[[冰]]和[[岩石]]組成，其中冰占天衛二表面的多數，而它的地幔和核心可能分別由冰和岩石組成。天卫二的構造與[[天衛四]]類似，但天衛四的體積比天衛二大35％。<ref name=NCKU />天卫二是天王星所有衛星中最暗的，反射率只有18％。<ref name = fd9000 />因為天卫二上有多處[[峽谷]]，內部可能有變動，因此天衛二可能有過一些地殼變動的事件。

天衛二在早期常常被隕石撞擊，因此表面上有大大小小的[[隕石坑]]，在天王星所有衛星裡隕石撞擊坑数量僅次於[[天衛四]]。最大的隕石坑直徑至少有210公里。天衛二其中一個表面特徵是在[[旺達隕石坑]]（{{lang|en|Wunda crater}}）最低點的一圈明亮圓環。<ref name = fd9000 />天衛二與天王星其它衛星一樣，可能是由天王星的[[吸積盤]]所組成。[[航海家二號]]經過天王星时深入研究过天卫二，这也是人類第一及唯一一次對其深入研究。[[航海家二號]]在經過天衛二时拍下的照片可以讓天文測繪家<ref>一種畫[[行星]]及[[衛星]]地形和表面的職業</ref>繪畫天衛二40％的表面。

== 發現與命名 ==
天衛二與另外一顆天王星衛星[[天衛一]]，由[[英國]][[天文學家]][[威廉·拉塞尔]]在1851年10月24號同時發現。<ref name="Lassell 1851" /><ref name="Lassell, letter 1851" />雖然[[天衛三]]和[[天衛四]]的發現人[[威廉·赫歇爾]]聲稱他在18世紀末曾經發現4顆未被發現天王星衛星<ref name="Herschel 1798" />，但他的觀測沒有被加以證實而不被承認。<ref name="Struve 1848" />

天王星所有的衛星都是以[[莎士比亞]]或[[亞歷山大·蒲柏]]作品中的角色來命名的。天衛二的名字烏姆柏里厄爾是由[[威廉·赫歇爾]]的兒子[[約翰·赫歇爾]]經威廉·拉塞尔的請求而推薦的。<ref name="Lassell 1852" />烏姆柏里厄爾在亞歷山大·蒲柏的《{{link-en|秀髮劫|The_Rape_of_the_Lock}}》（The Rape of the Lock）中被形容成是一隻「昏暗的憂鬱精靈」。同時，[[拉丁語]]中的umbra指的是陰影、影子的意思。

== 軌道 ==
天衛二環繞天王星的平均距離为266,000公里，在[[天王星的衛星|天王星五大衛星]]中距天王星第三遠。天衛二環繞天王星的[[離心率]]和[[軌道傾角]]都很小，分别只有0.0039和0.128。<ref name="orbit" />天衛二的[[軌道周期]]約為4.1個地球日，正好與它的自轉周期相同。也就是說，天衛二有[[同步軌道]]和[[潮汐鎖定]]的特性，使天衛二永遠只有一面面向天王星<ref name="Smith Soderblom et al. 1986" />。天衛二的軌道完全在天王星的[[磁層]]裡。<ref name="Grundy Young et al. 2006" />如果天衛二的[[後半球]]（沒有面對天王星的那一面）完全在天王星的磁層裡，天衛二會被環繞天王星的[[磁層等離子體]]擊中，並使天衛二的後半球呈一片黑暗。（除了天衛四以外，所有的天王星衛星都有這種特性。<ref name="Grundy Young et al. 2006" />）<ref name="Ness Acuña et al. 1986" />[[航海家二號]]在1977年經過天衛二時，衛星上的磁層等離子體遠比預測數量多，顯示出天衛二可能會吸收天王星磁層裡的等離子體。<ref name="Krimigis Armstrong et al. 1986" />

因為天王星是側著繞行[[太陽]]的，而[[天王星的衛星]]（包括天衛二）是在天王星的[[赤道]]面上運轉的。因此天衛二有很極端的[[季節|季節周期]]。天衛二的[[兩極]]，都會有連續42年的黑暗。黑暗過後，會有連續42年的陽光照射。在[[至日]]時，陽光會照到其中一極的最頂端。<ref name="Grundy Young et al. 2006" />在[[航海家二號]]經過天衛二時，正好遇到1986年南半球的[[夏至]]。因此航海家二號拍下的照片，每一張照片的北半球都是暗的。每隔42年，當天王星的赤道面與[[地球]]相交，且太陽照射到天王星的[[晝夜平分點]]時，便有可能發生[[掩星|衛星掩星]]的現象。在2007年，這種情況發生過3次。第一次是在2007年8月15日，由天衛二掩蓋天衛三。第二次是在8月19日，由天衛二掩蓋天衛一。而第三次是在12月8日，由天衛二掩蓋天衛三。<ref name="Miller Chanover 2009" /><ref name="Arlot Dumas et al. 2008" />

目前，天衛二尚未與其他天王星的衛星發生過[[軌道共振]]。但在早期可能與[[天衛五]]呈1:3的共振。軌道共振可能會增加天衛五的[[離心率]]，並促進天衛五的[[內熱]]與[[地質]]活動，而天衛二受到的影響較小。<ref name="Tittemore Wisdom 1990" />基於天王星[[扁橢球體|低扁]]的形狀，天王星的衛星要離開天王星會比[[木星]]或[[土星]]的卫星更容易。當天衛五不再與天衛二產生共振後，它的[[離心率]]會減振，並不再運用它的熱源。<ref name="Tittemore Wisdom 1989" /><ref name="Malhotra Dermott 1990" />

== 構造 ==
天衛二是[[天王星的衛星]]中[[天王星的衛星|直徑第三]]和[[天王星的衛星|質量第四]]的衛星。它的[[密度]]为1.39克/立方厘米。<ref name="Jacobson Campbell et al. 1992" />天衛二主要由[[冰|水冰]]所組成，與另一種高密度的成分構成天衛二40％的[[質量]]。<ref name="Hussmann Sohl et al. 2006" />有專家推測後这可能為[[岩石]]、[[碳]]和其他[[有機化合物]]所組成的一種物質。<ref name="Smith Soderblom et al. 1986" />利用[[紅外線|紅外]][[光譜|光譜術]]多次的分析後，發現天衛二表面上存在[[結晶]]状态的冰。<ref name="Grundy Young et al. 2006" />天衛二前半球的冰[[吸收帶]]比後半球的還要強。<ref name="Grundy Young et al. 2006" />這種吸收帶的強度不一致的原因不明，但可能與天王星[[磁層]]裡的帶電粒子相關（因後半球的帶電粒子比前半球多）。这些粒子會[[濺射]]冰，將冰裡的[[甲烷]]分解成水合物，並使其它[[有機物]]變暗，最後只剩一些黑暗並含[[碳]]豐富的[[殘基]]存在。<ref name="Grundy Young et al. 2006" />

科學家利用紅外光譜術分析天衛二後，偵測到的化合物除了冰以外，還有主要分布於天衛二的後半球的[[二氧化碳]]<ref name="Grundy Young et al. 2006" />，不过其來源不明。一個理論认为[[碳酸鹽]]受到天王星磁層裡的高能粒子的影響，進而產生二氧化碳。這個[[假說]]能解釋為什麼天衛二的二氧化碳的分佈不均勻（因後半球受到磁層的影響較大）。另一理論认为天衛二內部的冰裡的二氧化碳因天衛二的地質活動而突然[[釋氣]]。<ref name="Grundy Young et al. 2006" />

科學家推測天衛二的內部的岩[[地核|核]]被一層冰冷的[[地幔]]環繞。<ref name="Hussmann Sohl et al. 2006" />如果這是真的，天衛二內核（314公里）的[[半徑]]約為[[月球]]的54％，而質量則是月球的40％。天衛二的壓強為0.24[[1000000000|吉]][[帕斯卡]]。<ref name="Hussmann Sohl et al. 2006" />天衛二的地幔结构目前尚不清楚，但天衛二底下似乎不存在地下海洋。<ref name="Hussmann Sohl et al. 2006" />

== 表面特徵 ==
[[File:Umbriel usgsx2.jpg|thumb|表现出多边形特征的天卫二照片|alt=球状的蓝色表面布满了陨石坑和多边形特征。右下方的部分较为平坦。]]
天衛二是所有天王星衛星中最暗的。它反射的光是只有其大小相当的[[天衛一]]的一半。<ref name="JPLSSD" />与天衛一（23％）相比，天衛二的[[球面反照率]]很低（10％）。<ref name="Karkoschka 2001, Hubble" /> 當天衛二的[[行星照|相位角]]改變，它的[[幾何反照率]]會減小。當天衛二的相位角为0度时，反射率是26％。當其相位角为1度时，反射率會減至19％。這種情況是一種叫相對效應的[[光學現象]]。天衛二的表面是[[藍色|微藍色]]的，但隕石坑等地方較藍。<ref name="Plescia 1987" /><ref name="Bell McCord 1991" />天衛二的前半球和後半球甚至可能顏色不同（前者比後者紅）。<ref name="Buratti Mosher 1991" /> 天衛二紅色表面的原因有很多說法，其中一個理論是天衛二紅色的表面可能是由帶電粒子和[[微流星體]]造成的轟炸並使天衛二[[太空風化]]的結果。<ref name="Bell McCord 1991" />但較有可能是因為早期天衛二形成時，[[吸積盤]]裡含一種紅色的物質所造成的結果。<ref name="Bell McCord 1991" /><ref name="Buratti Mosher 1991" /> 

目前為止，科學家只承認天衛二上的一種地質特徵——[[隕石坑]]。<ref name="usgs" />天衛二的隕石坑比[[天衛一]]和[[天衛四]]的隕石坑更大更多。<ref name="Plescia 1987" />在所有天王星的衛星中，只有[[天衛三]]的隕石坑比天衛二的多。天衛二的隕石坑最小只有幾公里，但最大的隕石坑——[[沃科洛陨石坑]]直徑卻有210公里。<ref name="Plescia 1987" /><ref name="usgs" />天衛二所有被承認的隕石坑都有中央峰，但都沒有[[射紋系統]]。<ref name="Smith Soderblom et al. 1986" /><ref name="Plescia 1987" />

天衛二最著名的表面特徵旺達隕石坑位于天衛二的[[赤道]]上，它的直徑有131公里。<ref name="usgsWunda" /><ref name="hunt" />旺達隕石坑最低點有一圈明亮的[[光環]]，最有可能是[[沖淤變動]]的結果。<ref name="Plescia 1987" />在天衛二的[[晨昏圈]]上有兩個隕石坑：[[烏維隕石坑|烏維]]和[[史金德隕石坑|史金德]]，兩個隕石坑都沒有光圈，但都有中央峰。<ref name="hunt" /><ref name="Smith Soderblom et al. 1986" />科學家在研究天衛二的地形時，發現天衛二早期可能有一個直徑400公里、深5公里的隕石坑。<ref name="Moore Schenk et al. 2004" />

與天王星其他衛星一樣，天衛二的表面穿插著很多[[峽谷]]。<ref name="Croft1989" />但它們因影像的畫質太差而並沒有被正式承認。而影像的畫質正是研究天衛二[[地質圖]]的[[天文學家]]的絆腳石。<ref name="Plescia 1987" />

天衛二的表面於[[後期重轟炸期]]已穩定。<ref name="Plescia 1987" />目前，能提供给我們天衛二早期地表變化的線索只剩峽谷及多邊形—一種上百公里，有複雜形狀的暗班。<ref name="Helfenstein Thomas et al. 1989" />根據[[航海家二號]]當時拍下的測光照片，可以看出天衛二上的多邊形分佈不均勻，從衛星的東北部走向西南部。有些多邊形與其他窪地相對應，這種現象可能由天衛二早期的地質活動造成。<ref name="Helfenstein Thomas et al. 1989" />目前天文學家對為什麼天衛二這麼昏暗和整齊沒有合理的解釋。天衛二的表面可能被一層從隕石撞擊掊出或火山爆發噴發出來的暗的物質覆蓋。<ref name="Buratti Mosher 1991" />另外，天衛二的地殼可能完全由这種黑暗的物質所組成，並阻止射紋組成。但[[旺達隕石坑]]的光圈與此假說產生矛盾。<ref name="Smith Soderblom et al. 1986" />

=== 撞擊坑 ===
天衛二上的撞擊坑，多以神話中的邪惡、黑暗之神或神靈命名。
{| class="wikitable plainrowheaders sortable"
! scope="col" | 名稱
! scope="col" | 座標
! scope="col" | 直徑（公里）
! scope="col" | 名字來源
|-
! scope="row" | [[阿貝利希撞擊坑]]
| {{coord|33.6|S|42.2|E|globe:Umbriel|name=Alberich}}
| 52
| [[阿貝利希]]，[[北歐神話]]的[[侏儒 (北歐神話)|侏儒]]。
|-
! scope="row" | [[Fin撞擊坑]]
| {{coord|37.4|S|44.3|E|globe:Umbriel|name=Fin}}
| 43
| [[Fin (洞穴巨人)|Fin]]，[[丹麥]]民間傳說的[[洞穴巨人]]。
|-
! scope="row" | [[戈布撞擊坑]]
| {{coord|12.7|S|27.8|E|globe:Umbriel|name=Gob}}
| 88
| [[戈布]]，[[異教]]神。
|-
! scope="row" | [[卡纳罗阿撞擊坑]]
| {{coord|10.8|S|345.7|E|globe:Umbriel|name=Kanaloa}}
| 86
| [[卡纳罗阿]]，[[玻里尼西亞]]神話的冥界之神。
|-
! scope="row" | [[Malingee撞擊坑]]
| {{coord|22.9|S|13.9|E|globe:Umbriel|name=Malingee}}
| 164
| [[Malingee]]，[[澳大利亞原住民神話]]的惡神。
|-
! scope="row" | [[Minepa撞擊坑]]
| {{coord|42.7|S|8.2|E|globe:Umbriel|name=Minepa}}
| 58
| [[Minepa]]，[[莫三比克]][[Makua族]]的惡神。
|-
! scope="row" | [[帕里撞擊坑]]
| {{coord|9.2|S|4.3|E|globe:Umbriel|name=Peri}}
| 61
| [[帕里·帕伊里卡]]也叫佩里，[[波斯神話]]的妖精。
|-
! scope="row" | [[Setibos撞擊坑]]
| {{coord|30.8|S|346.3|E|globe:Umbriel|name=Setibos}}
| 50
| [[Setibos]]，[[巴塔哥尼亞]]的神。
|-
! scope="row" | [[史金德隕石坑|史金德撞擊坑]]
| {{coord|1.8|S|331.7|E|globe:Umbriel|name=Skynd}}
| 72
| [[史金德]]，[[丹麥]]民間傳說的[[洞穴巨人]]。
|-
! scope="row" | [[烏維隕石坑|烏維撞擊坑]]
| {{coord|4.7|S|311.6|E|globe:Umbriel|name=Vuver}}
| 98
| [[烏維]]，[[芬蘭]]民間傳說的邪神。
|-
! scope="row" | [[Wokolo撞擊坑]]
| {{coord|30|S|1.8|E|globe:Umbriel|name=Wokolo}}
| 208
| [[Wokolo]]，西非[[Bambara族]]傳說的惡魔。
|-
! scope="row" | [[旺達隕石坑|旺達撞擊坑]]
| {{coord|7.9|S|273.6|E|globe:Umbriel|name=Wunda}}
| 131
| [[旺達（神話人物）|旺達]]，[[澳大利亞原住民神話]]的黑暗精靈。
|-
! scope="row" | [[Zlyden撞擊坑]]
| {{coord|23.3|S|326.2|E|globe:Umbriel|name=Zlyden}}
| 44
| [[Zlyden]]，[[斯拉夫神話]]的惡靈。
|}

== 起源 ==
普遍認為天衛二是由[[吸積盤]]或[[星雲]]所形成的。組成天衛二的物體不是分佈在[[天王星]]附近，就是由一個大到讓天王星[[轉軸傾角|垂直傾斜]]的撞擊形成的。<ref name="Mousis 2004" />組成天衛二的星雲的成分不明，但天王星衛星的密度比土星的衛星大，可得知那團星雲缺少[[水|水分]]。在星雲裡數量很多的[[氮]]和[[碳]]可能以[[一氧化碳]]和[[氮分子]]，而不是[[氨]]或[[甲烷]]的方式存在。<ref name="Mousis 2004" />由星雲組成的衛星會含較少[[冰]]並含較多[[岩石]]，這能解釋天衛二的高密度。<ref name="Smith Soderblom et al. 1986" />

天衛二的[[吸積]]過程持續了幾千年，與吸積同一時間發生的[[隕石]]撞擊使天衛二的[[地殼]]發熱。<ref name="Mousis 2004" /><ref name="Squyres Reynolds et al. 1988" />天衛二被隕石撞擊後，最高溫度曾達180[[热力学温标|K]]，造成撞擊的隕石坑深達8公里。<ref name="Squyres Reynolds et al. 1988" />在天衛二吸積完後，天衛二地下開始[[冷卻]]，但因內部放射性元素衰變，天衛二內部仍然是熱的。<ref name="Smith Soderblom et al. 1986" />當天衛二近表面的地方開始收縮，它的[[地核]]和[[地幔]]開始膨脹。天衛二的這些運動使它的地殼受到很強的拉伸應力，並導致地殼裂開。<ref name="Hillier & Squyres 1991" /> 這個過程持續了兩百萬年，顯示出天衛二所有內源性的活動在幾十億年前就停止了。<ref name="Smith Soderblom et al. 1986" />

若天衛二早期有氨（以[[水合物]]存在）或[[盐 (化学)|鹽]]等[[抗凍劑]]存在，早期的吸積造成的熱能及放射性元素衰變会造成衛星部分的冰融化。<ref name="Hussmann Sohl et al. 2006" /><ref name="Squyres Reynolds et al. 1988" />天衛二的冰融化後，讓地底的冰與岩石分開，使天衛二的地幔由冰組成，地核由岩石組成。<ref name="Plescia 1987" />一層[[液態水]]可能存在於冰與岩石的邊界之間，但可能早已凍結。冰、岩石和水，這種混和物的[[共晶溫度]]176K，相當於-97.15[[攝氏度]]。<ref name="Hussmann Sohl et al. 2006" />

== 勘探 ==
目前唯一拍到的天衛二特寫是由[[航海家二號]]所拍下的照片。航海家二號在1986年1月飛越[[天王星]]時，拍下天衛二的照片。因為當時拍下照片時，航海家二號離天衛二325,000公里，所以航海家二號拍下的照片中，空間分辨率也只有5.2公里。<ref name="Plescia 1987" /><ref name="Stone 1987" />天衛二表面有40％被航海家二號拍到，但只有20％能供描繪地質圖參考。<ref name="Plescia 1987" />在飛越天衛二時，它的南半球正對著太陽，因此天衛二的北半球是完全黑暗的，同時也不能被研究。<ref name="Smith Soderblom et al. 1986" />除了航海家二號，沒有太空船曾經或計畫要到天衛二探勘。

== 参考文献 ==
;註釋
{{ReflistH|2}}
{{NoteFoot}}
{{ReflistF}}

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<ref name=UMoons>{{cite web
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<ref name=fd9000>{{cite web
 |url         = http://fd9000.150m.com/umbriel.htm
 |title       = 天衛二
 |accessdate  = 2012年7月27日
 |deadurl     = yes
 |archiveurl  = https://web.archive.org/web/20140306090617/http://fd9000.150m.com/umbriel.htm
 |archivedate = 2014年3月6日
}}</ref>
}}
== 外部連結 ==
{{Commons category}}

* {{cite web | url = http://solarsystem.nasa.gov/planets/profile.cfm?Object=Ura_Umbriel | title = Umbriel Profile | publisher = NASA's Solar System Exploration | access-date = 2009-10-10 | url-status = dead | archive-url = https://web.archive.org/web/20090826163708/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Ura_Umbriel | archive-date = 2009-08-26 }}
* {{cite journal | bibcode = 1851AN.....33..259L | title = Entdeckung von 2 neuen Uranus Trabanten | volume = 33 | issue = 17 | date = 1852 | pages = 259–262 | first = Herrn W. | last = Lassell | journal = Astronomische Nachrichten | language = de | doi = 10.1002/asna.18520331707 | url = https://zenodo.org/record/1424629 | access-date = 2022-06-09 | archive-date = 2022-10-03 | archive-url = https://web.archive.org/web/20221003071114/https://zenodo.org/record/1424629 | dead-url = no }}
* {{cite web | url = http://www.eso.org/public/news/eso0737/ | title = Edge-on! | publisher = [[Very Large Telescope]] | date = 2007-08-23 | access-date = 2010-01-14 | archive-date = 2022-10-03 | archive-url = https://web.archive.org/web/20221003071046/https://www.eso.org/public/news/eso0737/ | dead-url = no }}
* [http://www.solarviews.com/eng/umbriel.htm Umbriel page] {{Wayback|url=http://www.solarviews.com/eng/umbriel.htm |date=20221003071050 }} (including a [http://www.solarviews.com/raw/uranus/umbmap1.jpg labelled map of Umbriel] {{Wayback|url=http://www.solarviews.com/raw/uranus/umbmap1.jpg |date=20211126170649 }}) at ''Views of the Solar System''
* [http://planetarynames.wr.usgs.gov/Page/UMBRIEL/target Umbriel Nomenclature] {{Wayback|url=http://planetarynames.wr.usgs.gov/Page/UMBRIEL/target |date=20221003071112 }} from the [http://planetarynames.wr.usgs.gov/ USGS Planetary Nomenclature web site] {{Wayback|url=http://planetarynames.wr.usgs.gov/ |date=20120412082057 }}

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{{天卫二}}
{{天王星卫星}}
{{太陽系的衛星}}

[[Category:天王星的卫星|天卫02]]
[[Category:1851年发现的天体]]
[[Category:天卫二]]