View Full Version : Satun's Moon Iapetus

2004-Dec-30, 07:49 PM
Here's some new images of Iapetus from Cassini.
Six images of Iapetus by Cassini (http://photojournal.jpl.nasa.gov/jpeg/PIA06145.jpg)

2004-Dec-31, 12:00 AM
But where's the monolith? :D

2004-Dec-31, 12:35 AM
Originally posted by Nyrath@Dec 31 2004, 12:00 AM
But where's the monolith? :D
If I remeber correctly, it was supposed to be dead-center in a giant white ellipse on an otherwise charcoal colored moon. I am interested in Iapetus for exactly this reason, but realistically, it does not resemble what Clark desribed. I'm guessing there's no monolith.

2005-Jan-02, 12:26 AM
Hi everyone,

Here are the latest, and in my opinion, the best images of Saturn's moon Iapetus.

NASA's Cassini spacecraft made its closest approach to Saturn's moon Iapetus on New Year's Eve, passing only 123,400 km (76,700 miles) away. Iapetus is best known for its strange two-toned colour, one hemisphere is completely dark, and the other is white. At 1,400 km (890 miles) across, it's Saturn's third largest moon, and Jean-Dominique Cassini originally discovered it in 1672.

Out of more than 50 images returned by the Cassini spacecraft, only a handful revealed any real detail of the moon’s cratered surface, far less than the encounters with the moons Titan and Dione last December, that were more of a success story. The images shown here are full size so that you are able to view the moon's surface in fine detail. Note that the image resolution for images 3 & 4 are lower than those below that are the highest at 1.5 Km per pixel. The image sequance taken by Cassini are: images 3,4,1,2 as the spaceprobe moved past the moon during its close fly by.

Courtesy NASA/JPL.Caltech :rolleyes:


It is a little difficult to find something new to say about Iapetus that has not been said already on this occasion, except this is a strange moon among a retinue of 33 known satellites that orbit Saturn, Lord of the rings, and the images returned by Cassini a few days ago appear to confirm the existence of methane or ammonia ices within some of the large craters on the surface of Iapetus.

Lying at a distance of 4 million kilometres, the eccentric and inclined orbit of Iapetus lies on the outer boarder of Saturn’s moon system, and it always keeps one hemisphere permanently facing its parent planet. It has a density of 1.2 times that of water, and even today after the arrival of the Cassini Huygens spacecraft last July, planetary scientists believe Iapetus probably has methane and ammonia composing some of its geological make up.

Cassini’s recent close encounter on New Years’ eve sent the spacecraft past the leading hemisphere of Iapetus between longitude 70 – 180 degrees, that is known to be covered in material 6 – 10 times darker than its brighter cratered landscape of the Saturn facing hemisphere of this moon.

It is not known whether this dark material originates from within Iapetus or from a collision of a large body at some point in the moon’s history. The first image in this sequence of 4 clearly shows some form of huge impact in the top half of the frame, that must have occurred in the moon’s past, and therefore at least half confirms this theory. ;)

The difficulty remains that because some of this dark material lies on the floor of many of Iapetus’s numerous craters, planetary scientists remain convinced that the material is of internal origin and is due to the eruption of methane, and similar elements, in a form of cryo volcanic activity on the moon. For this reason, astronomers are awaiting the spectroscopic analysis, and other science results of Iapetus (as measured by the Cassini spacecraft) to be released. :)

However, the photographs shown here are the clearest and best resolution images ever taken of Iapetus by a robotic spacecraft. :D


2005-Jan-02, 12:46 AM
My apologies Antoniseb, I did not realise until after starting a new post on Saturn's moon Iapetus that you had already started this topic. Perhaps a member of the Moderator team may merge these two topics. :(


2005-Jan-02, 01:25 PM
Originally posted by Richard0802@Jan 2 2005, 12:46 AM
Perhaps a member of the Moderator team may merge these two topics.
Done, and no apology needed.

2005-Jan-02, 03:30 PM
Thanks Antoniseb.


Images courtesy NASA/JPL/Caltech :rolleyes:

Science Correspondent

2005-Jan-09, 06:38 AM
Originally posted by Nyrath@Dec 31 2004, 12:00 AM
But where's the monolith? :D
here i am :rolleyes: