File:Iapetus by Voyager 2 - enhanced.jpg
From Wikimedia Commons, the free media repository
Jump to navigation
Jump to search
Iapetus_by_Voyager_2_-_enhanced.jpg (350 × 350 pixels, file size: 19 KB, MIME type: image/jpeg)
File information
Structured data
Captions
DescriptionIapetus 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 |
||
Date | Taken on 22 August 1981 | ||
Source | http://photojournal.jpl.nasa.gov/catalog/PIA00348 | ||
Author | NASA/JPL/USGS | ||
Other versions |
|
Licensing[edit]
Public domainPublic domainfalsefalse |
This file is in the public domain in the United States because it was solely created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See Template:PD-USGov, NASA copyright policy page or JPL Image Use Policy.) | ||
Warnings:
|
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 17:29, 4 April 2005 | 350 × 350 (19 KB) | Smartech~commonswiki (talk | contribs) | *'''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 |
You cannot overwrite this file.
File usage on Commons
The following page uses this file:
File usage on other wikis
The following other wikis use this file:
- Usage on ar.wikipedia.org
- Usage on bar.wikipedia.org
- Usage on be-tarask.wikipedia.org
- Usage on be.wikipedia.org
- Usage on ca.wikipedia.org
- Usage on de.wikipedia.org
- Usage on el.wikipedia.org
- Usage on en.wikipedia.org
- Usage on eo.wikipedia.org
- Usage on es.wikipedia.org
- Usage on eu.wikipedia.org
- Usage on fr.wikipedia.org
- Usage on gl.wikipedia.org
- Usage on hr.wikipedia.org
- Usage on it.wikipedia.org
- Usage on ja.wikipedia.org
- Usage on ko.wikipedia.org
- Usage on la.wikipedia.org
- Usage on lb.wikipedia.org
- Usage on lt.wikipedia.org
- Usage on lv.wikipedia.org
- Usage on ms.wikipedia.org
- Usage on mwl.wikipedia.org
- Usage on no.wikipedia.org
- Usage on pl.wikipedia.org
View more global usage of this file.
Metadata
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.
_error | 0 |
---|