Prometheus 土卫十六(中英)
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Prometheus is the third of Saturn1's known satellites:

  orbit:    139,350 km from Saturn

  diameter: 91 km (145 x 85 x 62)

  mass:     2.7e17 kg

  Prometheus was a Titan who stole fire from Olympus and gave it to humankind, for which Zeus punished him horribly; son of Iapetus; brother of Atlas2 and Epimetheus. "Prometheus" is Greek for "foresight3".

  Discovered by S. Collins and others in 1980 from Voyager photos.

  Prometheus is the inner shepherd satellite of the F ring.

  Prometheus has a number of ridges4 and valleys and several craters5 about 20 km in diameter but appears to be less cratered6 than the neighboring moons Pandora, Janus and Epimetheus.

  From their very low densities7 and relatively8 high albedos, it seems likely that Prometheus, Pandora, Janus and Epimetheus are very porous9 icy bodies. (Note, however, that there is a lot of uncertainty10 in these values.)

  The 1995/6 Saturn Ring Plane Crossing observations found that Prometheus was lagging by 20 degrees from where it should have been based on Voyager 1981 data. This is much more than can be explained by observational error. It is possible that Prometheus's orbit was changed by a recent encounter with the F ring, or it may have a small companion moon sharing its orbit.

  Prometheus 是距土星第三近卫星:

  公转轨道:距土星 139,350 千米

  卫星直径:91 千米(145×85×62)

  质量:2.7e17 千克

  Prometheus(普罗米修斯)是一位从奥林匹斯山偷走火种并把它带到人间的巨人。就因为这,宙斯用残忍的手段来惩罚他;他是Iapetus的儿子,Atlas和Epimetheus的兄弟。它在希腊语中意为“深思远虑”

  它是被S. Collins和其他一些人于1980年从旅行者号传回的照片中发现的。

  土卫十六是F光环中的一颗牧羊卫星。

  土卫十六有许多山脉和山谷和一些直径为20千米左右的陨石坑。但是看上去它的陨石坑比周围邻近的卫星(土卫十七,土卫十和土卫十一)少。

  从它们很低的密度和相对较高的反照率来看,土卫十六,土卫十七,土卫十和土卫十一可能是多孔的冰质天体。(注解:对于这些数值还有很多不能确定。)

  根据1995年6月的土星光环平面交叉线观察发现,土卫十六比从旅行者号1981年数据算出的所在位置落后了20度,这是不足以用观察误差所能解释的。可能土卫十六的轨道最近与F环遭遇而发生改变或者他可能有一个小伴星与它一起分享这个轨道。



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1 Saturn tsZy1     
n.农神,土星
参考例句:
  • Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪,为什么只有土星有光环。
  • These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们,土星由较轻的物质构成。
2 atlas vOCy5     
n.地图册,图表集
参考例句:
  • He reached down the atlas from the top shelf.他从书架顶层取下地图集。
  • The atlas contains forty maps,including three of Great Britain.这本地图集有40幅地图,其中包括3幅英国地图。
3 foresight Wi3xm     
n.先见之明,深谋远虑
参考例句:
  • The failure is the result of our lack of foresight.这次失败是由于我们缺乏远虑而造成的。
  • It required a statesman's foresight and sagacity to make the decision.作出这个决定需要政治家的远见卓识。
4 ridges 9198b24606843d31204907681f48436b     
n.脊( ridge的名词复数 );山脊;脊状突起;大气层的)高压脊
参考例句:
  • The path winds along mountain ridges. 峰回路转。
  • Perhaps that was the deepest truth in Ridges's nature. 在里奇斯的思想上,这大概可以算是天经地义第一条了。
5 craters 1f8461e3895b38f51c992255a1c86823     
n.火山口( crater的名词复数 );弹坑等
参考例句:
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》
6 cratered f3774327dd107353b75750c68f1e81c7     
adj.有坑洞的,多坑的v.火山口( crater的过去分词 );弹坑等
参考例句:
  • The surface cratered with the constant dropping of water. 表面因经常滴水而成坑。 来自《现代英汉综合大词典》
  • Artillery cratered the roads. 炮击后大路布满了弹坑。 来自《现代英汉综合大词典》
7 densities eca5c1ea104bef3058e858fe084fb6d0     
密集( density的名词复数 ); 稠密; 密度(固体、液体或气体单位体积的质量); 密度(磁盘存贮数据的可用空间)
参考例句:
  • The range of densities of interest is about 3.5. 有用的密度范围为3.5左右。
  • Densities presumably can be probed by radar. 利用雷达也许还能探测出气体的密度。
8 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
9 porous 91szq     
adj.可渗透的,多孔的
参考例句:
  • He added sand to the soil to make it more porous.他往土里掺沙子以提高渗水性能。
  • The shell has to be slightly porous to enable oxygen to pass in.外壳不得不有些细小的孔以便能使氧气通过。
10 uncertainty NlFwK     
n.易变,靠不住,不确知,不确定的事物
参考例句:
  • Her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。
  • After six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后,压力开始产生影响了。
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