File:Iapetus by Voyager 2 - enhanced.jpg
来自Wikimedia Commons
跳转到导航
跳转到搜索
Iapetus_by_Voyager_2_-_enhanced.jpg (350 × 350像素,文件大小:19 KB,MIME类型:image/jpeg)
文件信息
结构化数据
说明
说明
添加一行文字以描述该文件所表现的内容
描述Iapetus by Voyager 2 - enhanced.jpg |
English: Iapetus by Voyager 2 spacecraft, August 22, 1981
Saturn's outermost large moon, Iapetus, has a bright, heavily cratered icy terrain and a dark terrain, as shown in this Voyager 2 image taken on August 22, 1981. Amazingly, the dark material covers precisely the side of Iapetus that leads in the direction of orbital motion around Saturn (except for the poles), whereas the bright material occurs on the trailing hemisphere and at the poles. The bright terrain is made of dirty ice, and the dark terrain is surfaced by carbonaceous molecules, according to measurements made with Earth-based telescopes. Iapetus' dark hemisphere has been likened to tar or asphalt and is so dark that no details within this terrain were visible to Voyager 2. The bright icy hemisphere, likened to dirty snow, shows many large impact craters. The closest approach by Voyager 2 to Iapetus was a relatively distant 600,000 miles, so that our best images, such as this, have a resolution of about 12 miles. The dark material is made of organic substances, probably including poisonous cyano compounds such as frozen hydrogen cyanide polymers. Though we know a little about the dark terrain's chemical nature, we do not understand its origin. Two theories have been developed, but neither is fully satisfactory--(1) the dark material may be organic dust knocked off the small neighboring satellite Phoebe and "painted" onto the leading side of Iapetus as the dust spirals toward Saturn and Iapetus hurtles through the tenuous dust cloud, or (2) the dark material may be made of icy-cold carbonaceous "cryovolcanic" lavas that were erupted from Iapetus' interior and then blackened by solar radiation, charged particles, and cosmic rays. A determination of the actual cause, as well as discovery of any other geologic features smaller than 12 miles across, awaits the Cassini Saturn orbiter to arrive in 2004 |
||
日期 | 摄于1981年8月22日 | ||
来源 | http://photojournal.jpl.nasa.gov/catalog/PIA00348 | ||
作者 | NASA/JPL/USGS | ||
其他版本 |
|
许可协议
[编辑]Public domainPublic domainfalsefalse |
![]() |
本文件完全由NASA创作,在美国属于公有领域。根据NASA的版权方针,NASA的材料除非另有声明否则不受版权保护。(参见Template:PD-USGov/zh、NASA版权方针页面或JPL图片使用方针。) | ![]() |
![]() |
警告:
|
文件历史
点击某个日期/时间查看对应时刻的文件。
日期/时间 | 缩略图 | 大小 | 用户 | 备注 | |
---|---|---|---|---|---|
当前 | 2005年4月4日 (一) 17:29 | ![]() | 350 × 350(19 KB) | Smartech~commonswiki(留言 | 贡献) | *'''Iapetus by Voyager 2 spacecraft, August 22, 1981''' *same as Iapetus_by_Voyager_2.jpg but focused on the mooon and feature-enhanced. *original image caption: Saturn's outermost large moon, Iapetus, has a bright, heavily cratered icy terrain and a da |
您不可以覆盖此文件。
文件用途
以下页面使用本文件:
全域文件用途
以下其他wiki使用此文件:
- ar.wikipedia.org上的用途
- bar.wikipedia.org上的用途
- be-tarask.wikipedia.org上的用途
- be.wikipedia.org上的用途
- ca.wikipedia.org上的用途
- de.wikipedia.org上的用途
- el.wikipedia.org上的用途
- en.wikipedia.org上的用途
- eo.wikipedia.org上的用途
- es.wikipedia.org上的用途
- eu.wikipedia.org上的用途
- fr.wikipedia.org上的用途
- gl.wikipedia.org上的用途
- hr.wikipedia.org上的用途
- it.wikipedia.org上的用途
- ja.wikipedia.org上的用途
- ko.wikipedia.org上的用途
- la.wikipedia.org上的用途
- lb.wikipedia.org上的用途
- lt.wikipedia.org上的用途
- lv.wikipedia.org上的用途
- ms.wikipedia.org上的用途
- mwl.wikipedia.org上的用途
- no.wikipedia.org上的用途
- pl.wikipedia.org上的用途
查看此文件的更多全域用途。
元数据
此文件含有额外信息,这些信息可能是创建或数字化该文件时使用的数码相机或扫描仪所添加的。如果文件已从其原始状态修改,某些详细信息可能无法完全反映修改后的文件。
_error | 0 |
---|