土衛八 Iapetus：有奇怪地表 ê 衛星

探索宇宙¹！逐工會揀一幅無仝款 ê 影像抑是相片，𤆬你熟似咱這个迷人 ê 宇宙，閣有專業天文學者²為你解說³。

• 原始文章：Saturn's Iapetus: Moon with a Strange Surface
• 影像來源：NASA, ESA, JPL, SSI, Cassini Imaging Team
• 台文翻譯：An-Li Tsai (NCU)

[漢羅] 土衛八 Iapetus：有奇怪地表 ê 衛星

是啥毋原因，予這粒衛星 看起來敢若是一粒核桃？ 咱會使 tī 這張相片較倚下底 ê 部份，看著一輾奇怪 ê 山龍 踅 tī 土星 ê 衛星，土衛八 Iapetus ê 赤道頂懸。 所以這粒衛星，才會看起來 敢若是 逐家攏 足愛食 ê 美國塗豆。 咱到今猶毋知 這條山龍 ê 來源，毋過有幾若个假說咧解說這个現象。 一个是講，這是 ùi 地下 chu̍t 出來 ê 冰。 另外嘛有講，這是踅衛星 ê 環落落來 ê 結果。 閣有講，這是 10 億年前衛星形成留落來 ê 結構。 閣有一項奇怪 ê 代誌是，土衛八 Iapetus 有一半較烏，所以咱若是 ùi 地球看，會 giōng 欲看無。 毋過 另外一半 相對來講，就足光--ê。 是講，觀測 著--ê 地形烏暗度 會遮爾齊勻，實在是足奇怪 ê 代誌。 有可能是最近才有一重深色 ê 地皮崁 tī 較古老、滿面隕石坑 ê 地表頂懸。 落尾欲看 ê 是，土衛八 Iapetus 頂懸有幾若个較大 ê 衝擊盆地。 尤其是相片中央彼个 400 公里闊 ê 隕石坑。 咱看會著外沿有 足深 ê 山崁，予坑仔墘 kah 坑底有明顯 ê 懸低差。 這張相片 是 踅土星 ê Cassini 太空船 tī 2004 年底 飛過土衛八 Iapetus ê 時陣翕--ê。

[POJ] Thó͘-ōe-peh Iapetus: Ū kî-koài tē-piáu ê Ōe-chheⁿ

Sī siáⁿ-mi̍h goân-in, hō͘ chit-lia̍p ōe-chheⁿ khòaⁿ--khí-lâi ká-ná sī chi̍t-lia̍p hu̍t-thô? Lán ē-sái tī chit-tiuⁿ siòng-phìⁿ khah óa ē-té ê pō͘-hūn, khòaⁿ-tio̍h chi̍t-liàn kî-koài ê soaⁿ-lêng se̍h tī Thó͘-chheⁿ ê ōe-chheⁿ, Thó͘-ōe-peh Iapetus ê chhek-tō téng-koân. Só͘-í chit-lia̍p ōe-chheⁿ, chiah ē khòaⁿ--khí-lâi ká-ná sī ta̍k-ke lóng chiok ài-chia̍h ê Bí-kok thô͘-tāu. Lán kàu-taⁿ iáu m̄-chai chit-tiâu soaⁿ-lêng ê lâi-goân, m̄-koh ū kúi-ā-ê ká-soat leh kái-soeh chit-ê hiān-siōng. Chi̍t-ê sī kóng, che sī ùi tē-hā chu̍t--chhut-lâi ê peng. Lēng-gōa mā ū kóng, che sī se̍h ōe-chheⁿ ê ōe-chheⁿ-khoân lak--lo̍h-lâi ê kiat-kó. Koh ū kóng, che sī 10 ek nî chêng ōe-chheⁿ hêng-sêng lâu--lo̍h-lâi ê kiat-kò͘. Koh ū chi̍t-hāng kî-koài ê tāi-chì sī, Thó͘-ōe-peh Iapetus ū chi̍t-pòaⁿ khah o͘, só͘-í lán nā-sī ùi Tē-kiû khòaⁿ, ē giōng beh khòaⁿ-bô. M̄-koh lēng-gōa chi̍t-pòaⁿ siong-tùi lâi kóng, to̍h chiok kng--ê. Sī kóng, koan-chhek tio̍h ê tē-hêng o͘-àm-tō͘ ē chiah-nī chiâu-ûn, si̍t-chāi sī chiok kî-koài ê tāi-chì. Ū khó-lêng sī chòe-kīn chiah ū chi̍t-têng chhim-sek ê tē-phôe khàm tī khah kó͘-nó͘, móa-bīn ún-se̍k-kheⁿ ê tē-piáu téng-koân. Lo̍h-bóe beh khòaⁿ ê sī, Thó͘-ōe-peh Iapetus téng-koân ū kúi-ā-ê khah tōa ê chhiong-kek phûn-tē. Iû-kî sī siòng-phìⁿ tiong-ng hit-ê 400 kong-lí khoah ê ún-se̍k-kheⁿ. Lán khòaⁿ-ē-tio̍h gōa-iân ū chiok chhim ê soaⁿ-khàm, hō͘ kheⁿ-á-kîⁿ kah kheⁿ-té ū bêng-hián ê koân-kē chha. Chit-tiuⁿ siòng-phìⁿ sī se̍h Thó͘-chheⁿ ê Cassini Thài-khong-chûn tī 2004 nî té poe-kòe Thó͘-ōe-peh Iapetus ê sî-chūn hip--ê.

[KIP] Thóo-uē-peh Iapetus: Ū kî-kuài tē-piáu ê Uē-tshenn

Sī siánn-mi̍h guân-in, hōo tsit-lia̍p uē-tshenn khuànn--khí-lâi ká-ná sī tsi̍t-lia̍p hu̍t-thô? Lán ē-sái tī tsit-tiunn siòng-phìnn khah uá ē-té ê pōo-hūn, khuànn-tio̍h tsi̍t-liàn kî-kuài ê suann-lîng se̍h tī Thóo-tshenn ê uē-tshenn, Thóo-uē-peh Iapetus ê tshik-tō tíng-kuân. Sóo-í tsit-lia̍p uē-tshenn, tsiah ē khuànn--khí-lâi ká-ná sī ta̍k-ke lóng tsiok ài-tsia̍h ê Bí-kok thôo-tāu. Lán kàu-tann iáu m̄-tsai tsit-tiâu suann-lîng ê lâi-guân, m̄-koh ū kuí-ā-ê ká-suat leh kái-sueh tsit-ê hiān-siōng. Tsi̍t-ê sī kóng, tse sī uì tē-hā tsu̍t--tshut-lâi ê ping. Līng-guā mā ū kóng, tse sī se̍h uē-tshenn ê uē-tshenn-khuân lak--lo̍h-lâi ê kiat-kó. Koh ū kóng, tse sī 10 ik nî tsîng uē-tshenn hîng-sîng lâu--lo̍h-lâi ê kiat-kòo. Koh ū tsi̍t-hāng kî-kuài ê tāi-tsì sī, Thóo-uē-peh Iapetus ū tsi̍t-puànn khah oo, sóo-í lán nā-sī uì Tē-kiû khuànn, ē giōng beh khuànn-bô. M̄-koh līng-guā tsi̍t-puànn siong-tuì lâi kóng, to̍h tsiok kng--ê. Sī kóng, kuan-tshik tio̍h ê tē-hîng oo-àm-tōo ē tsiah-nī tsiâu-ûn, si̍t-tsāi sī tsiok kî-kuài ê tāi-tsì. Ū khó-lîng sī tsuè-kīn tsiah ū tsi̍t-tîng tshim-sik ê tē-phuê khàm tī khah kóo-nóo, muá-bīn ún-si̍k-khenn ê tē-piáu tíng-kuân. Lo̍h-bué beh khuànn ê sī, Thóo-uē-peh Iapetus tíng-kuân ū kuí-ā-ê khah tuā ê tshiong-kik phûn-tē. Iû-kî sī siòng-phìnn tiong-ng hit-ê 400 kong-lí khuah ê ún-si̍k-khenn. Lán khuànn-ē-tio̍h guā-iân ū tsiok tshim ê suann-khàm, hōo khenn-á-kînn kah khenn-té ū bîng-hián ê kuân-kē tsha. Tsit-tiunn siòng-phìnn sī se̍h Thóo-tshenn ê Cassini Thài-khong-tsûn tī 2004 nî té pue-kuè Thóo-uē-peh Iapetus ê sî-tsūn hip--ê.

[English] Saturn's Iapetus: Moon with a Strange Surface

What would make a moon look like a walnut? A strange ridge that circles Saturn's moon Iapetus's equator, visible near the bottom of the featured image, makes it appear similar to a popular edible nut. The origin of the ridge remains unknown, though, with hypotheses including ice that welled up from below, a ring that crashed down from above, and structure left over from its formation perhaps 100 million years ago. Also strange is that about half of Iapetus is so dark that it can nearly disappear when viewed from Earth, while the rest is, reflectively, quite bright. Observations show that the degree of darkness of the terrain is strangely uniform, as if a dark coating was somehow recently applied to an ancient and highly cratered surface. Last, several large impact basins occur around Iapetus, with a 400-kilometer wide crater visible near the image center, surrounded by deep cliffs that drop sharply to the crater floor. The featured image was taken by the Saturn-orbiting Cassini spacecraft during a flyby of Iapetus at the end of 2004.

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