土星 ê 衛星 Iapetus：3D ê 彩繪衛星

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: Painted Moon in 3D
• 影像來源：NASA, ESA, JPL, SSI, Cassini Imaging Team; 3D Rendering: NASA's VTAD
• 台文翻譯：An-Li Tsai (NCU)

[漢羅] 土星 ê 衛星 Iapetus：3D ê 彩繪衛星

土星 ê 衛星 Iapetus 是發生啥物代誌？ 這个 奇怪 ê 世界 有足濟部份是較暗 ê 咖啡色，其他部份是較光 ê 白色。 較暗物質 ê 組成成份猶毋知，毋閣 紅外線 光譜 表示伊有可能有 碳 ê 成份 tī--lih。 Iapetus 閣有一个特別 ê 赤道脊，予伊看起來敢若是一粒 核桃。 為著欲了解這粒彩繪衛星，NASA tī 2007 年直接送 Cassini 機器人太空船 到踅土星 ê 軌道去，予伊會當衝到離 Iapetus 2000 公里 近 ê 所在來 kā 看。 這張是 Iapetus ê 3D 影像。 Tī 南部有一个巨型 ê 隕石坑，差不多有 450 公里闊，敢若是疊 tī 另外一个差不多平大 ê、較老 ê 隕石坑 面頂。 較暗 ê 物質 看起來有足濟攏崁 tī Iapetus ê 上東爿，予隕石坑 kah 高地看起來攏差不多平暗。 認真檢查 了後，發現這个較暗 ê 表面物質通常是 tùi 著衛星赤道，而且伊比一公尺較薄。 目前 主流 ê 假說 是講，這个較暗 ê 物質，大部份是垃圾冰溫度變懸 昇華 了後，賰 ê 物質。 這个 較暗 ê 表面物質，上開始可能是 ùi 其他衛星 落過來產生 ê 流星殘骸，累積、崁 tī 這粒衛星表面 ê 結果。

[POJ] Thó͘-chhiⁿ ê ūi-chhiⁿ Iapetus: Saⁿ-D ê chhái-hōe ūi-chhiⁿ

Thó͘-chhiⁿ ê ūi-chhiⁿ Iapetus sī hoat-seng siáⁿ-mih tāi-chì? Chit-ê kî-koài ê sè-kài ū chiok-chōe pō͘-hūn sī khah-àm ê ka-pi-sek, kî-tha pō͘-hūn sī khah-kng ê pe̍h-sek. Khah-àm bu̍t-chit ê cho͘-sêng sêng-hūn iáu m̄-chai, m̄-koh âng-gōa-sòaⁿ kng-phó͘ piáu-sī i ū khó-lêng ū thòaⁿ ê sêng-hūn tī--lih. Iapetus koh-ū chi̍t-ê te̍k-pia̍t ê chhek-tō-chit, hō͘ i khòaⁿ--khí-lâi ká-ná sī chi̍t-lia̍p hu̍t-thô͘. Ūi-tio̍h beh liáu-kái chit-lia̍p chhái-hōe ūi-chhiⁿ, NASA tī jī-khòng-khòng-chhit nî ti̍t-chiap sàng Cassini ke-khì-lâng thài-khong-chûn kàu se̍h Thó͘-chhiⁿ ê kúi-tō khì, hō͘ i ē-tàng chhiong-kàu lî Iapetus nn̄g-chheng kong-lí koân kīn ê só͘-chāi lâi kā khòaⁿ. Chit-tiuⁿ sī Iapetus ê saⁿ-D iáⁿ-siōng. Tī lâm-pō͘ ū chi̍t-ê kū-hêng ê ún-se̍k-kheⁿ, chha-put-to ū sì-pah-gō͘-cha̍p kong-lí khoah, ká-ná sī tha̍h tī lēng-gōa chi̍t-ê chha-put-to pêⁿ-tōa ê, khah-lāu ê ún-se̍k-kheⁿ bīn-téng. Khah-àm ê bu̍t-chit khòaⁿ--khí-lâi ū chiok-chōe lóng khàm tī Iapetus ê siōng tang-pêng, hō͘ ún-se̍k-kheⁿ kah ko-tē khòaⁿ--khí-lâi lóng chha-put-to pêⁿ-àm. Jīn-chin kiám-cha liáu-āu, hoat-hiān chit-ê khah-àm ê piáu-bīn bu̍t-chit thong-siông sī tùi tio̍h ūi-chhiⁿ chhek-tō, jî-chhiáⁿ i pí chi̍t kong-chhioh khah-po̍h. Bo̍k-chêng chú-liû ê ká-soat sī-kóng, chit-ê khah-àm ê bu̍t-chit, tōa-pō͘-hūn sī lah-sap-peng un-tō͘ piàn-koân seng-hôa liáu-āu, chhun ê bu̍t-chit. Chit-ê khah-àm ê piáu-bīn bu̍t-chit, siōng khai-sí khó-lêng sī ùi kî-tha ūi-chhiⁿ la̍k-kòe-lâi sán-seng ê liû-chhiⁿ chân-hâi, lúi-chek, khàm tī chit-lia̍p ūi-chhiⁿ piáu-bīn ê kiat-kó.

[KIP] Thóo-tshinn ê uī-tshinn Iapetus: Sann-D ê tshái-huē uī-tshinn

Thóo-tshinn ê uī-tshinn Iapetus sī huat-sing siánn-mih tāi-tsì? Tsit-ê kî-kuài ê sè-kài ū tsiok-tsuē pōo-hūn sī khah-àm ê ka-pi-sik, kî-tha pōo-hūn sī khah-kng ê pe̍h-sik. Khah-àm bu̍t-tsit ê tsoo-sîng sîng-hūn iáu m̄-tsai, m̄-koh âng-guā-suànn kng-phóo piáu-sī i ū khó-lîng ū thuànn ê sîng-hūn tī--lih. Iapetus koh-ū tsi̍t-ê ti̍k-pia̍t ê tshik-tō-tsit, hōo i khuànn-khí-lâi ká-ná sī tsi̍t-lia̍p hu̍t-thôo. Uī-tio̍h beh liáu-kái tsit-lia̍p tshái-huē uī-tshinn, NASA tī jī-khòng-khòng-tshit nî ti̍t-tsiap sàng Cassini ke-khì-lâng thài-khong-tsûn kàu se̍h Thóo-tshinn ê kuí-tō khì, hōo i ē-tàng tshiong-kàu lî Iapetus nn̄g-tshing kong-lí kuân kīn ê sóo-tsāi lâi kā khuànn. Tsit-tiunn sī Iapetus ê sann-D iánn-siōng. Tī lâm-pōo ū tsi̍t-ê kū-hîng ê ún-si̍k-khenn, tsha-put-to ū sì-pah-gōo-tsa̍p kong-lí khuah, ká-ná sī tha̍h tī līng-guā tsi̍t-ê tsha-put-to pênn-tuā ê, khah-lāu ê ún-si̍k-khenn bīn-tíng. Khah-àm ê bu̍t-tsit khuànn-khí-lâi ū tsiok-tsuē lóng khàm tī Iapetus ê siōng tang-pîng, hōo ún-si̍k-khenn kah ko-tē khuànn-khí-lâi lóng tsha-put-to pênn-àm. Jīn-tsin kiám-tsa liáu-āu, huat-hiān tsit-ê khah-àm ê piáu-bīn bu̍t-tsit thong-siông sī tuì tio̍h uī-tshinn tshik-tō, jî-tshiánn i pí tsi̍t kong-tshioh khah-po̍h. Bo̍k-tsîng tsú-liû ê ká-suat sī-kóng, tsit-ê khah-àm ê bu̍t-tsit, tuā-pōo-hūn sī lah-sap-ping un-tōo piàn-kuân sing-huâ liáu-āu, tshun ê bu̍t-tsit. Tsit-ê khah-àm ê piáu-bīn bu̍t-tsit, siōng khai-sí khó-lîng sī uì kî-tha uī-tshinn la̍k-kuè-lâi sán-sing ê liû-tshinn tsân-hâi, luí-tsik, khàm tī tsit-lia̍p uī-tshinn piáu-bīn ê kiat-kó.

[English] Saturn's Iapetus: Painted Moon in 3D

What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark brown, while others are as bright white. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon. Iapetus also has an unusual equatorial ridge that makes it appear like a walnut. To help better understand this seemingly painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. Iapetus is pictured here in 3D. A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size. The dark material is seen increasingly coating the easternmost part of Iapetus, darkening craters and highlands alike. Close inspection indicates that the dark coating typically faces the moon's equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates. An initial coating of dark material may have been effectively painted on by the accretion of meteor-liberated debris from other moons.

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