Epimetheus 土卫十一(中英)

Epimetheus is the fifth of Saturn¹'s known satellites:

　　orbit: 151,422 km from Saturn

　　diameter: 115 km (144 x 108 x 98)

　　mass: 5.6e17 kg

　　Epimetheus was the son of Iapetus and brother of Prometheus and Atlas²; husband of Pandora. "Epimetheus" is Greek for "hindsight".

　　Epimetheus was first observed by Walker in 1966. But the situation was confused since Janus is in a very similar orbit. So Walker officially shares the discovery of Epimetheus with Fountain and Larson who showed in 1977 that there were two satellites involved. The situation was clarified in 1980 by Voyager 1.

　　The dark line across the surface in the Voyager image to the left is actually the shadow of the Saturn's F-ring.

　　Epimetheus and Janus are "co-orbital".

　　There are several craters³ larger than 30 km in diameter as well as both large and small ridges⁴ and grooves⁵. The extensive cratering⁶ indicates that Epimetheus must be quite old.

　　Epimetheus 是土星已知卫星中距其第五近的一颗：

　　公转轨道：距土星 151,422 千米

　　卫星直径：115 千米（144×108×98）

　　质量：5.6e17 千克

　　Epimetheus是Iapetus的儿子，普罗米修斯和Atlas的兄弟；潘多拉的丈夫。它在希腊语中的意思是“事后的认识”。

　　土卫十一首先是在1966年被步行者号发现的。但是这种看法被否定了，这是因为土卫十在一个十分相近的轨道，所以步行者号在官方上同Fountain和Larson分享它的发现成果。那两个人在1977年表示在那里包含着两颗不同的卫星，这种情况在1980年由旅行者1号证实了。

　　土卫十一与土卫十为"双星"。

　　它的表面有许多直径大于30千米的陨石坑（环形山），也有大大小小的山脉和沟。人们广泛的概念认为土卫十一一定十分古老。

　　上图中穿过表面的暗条纹实际是土星F光环的影子。