Skip to comments.Mystery of Saturn's Two-Faced Moon Solved
Posted on 10/09/2007 12:31:36 PM PDT by martin_fierro
Mystery of Saturn's Two-Faced Moon Solved
SPACE.com Tue Oct 9, 8:45 AM ET
Saturn's moon Iapetus has virtually no gray. Rather, its features are all stark black and white. The appearance has long puzzled astronomers.
New detailed images suggest sunlight is melting ice on one side of Iapetus, leaving the moon's dark surface exposed, while the opposite half retains its reflective ice-mixed shell.
Since the moon's discovery by Giovanni Domenico Cassini in 1671, Iapetus' appearance has baffled astronomers. The leading edge of Iapetus, which faces the direction of its orbit, is black as asphalt, while its trailing side appears bright as snow. Iapetus is 907 miles (1,460 kilometers) wide and circles Saturn at a distance of about 2.2 million miles (3.6 million kilometers).
High-resolution images of Iapetus acquired last month by the Cassini-Huygens spacecraft during its low pass over the moon have uncovered telling details on its surface that may well yield the reason for its strange bright and dark patterns.
"While there are many details yet to be worked out, we think we now understand the essence of why Iapetus looks the way it does," said Carolyn Porco, the leader of the imaging team at the Space Science Institute in Boulder, Colo.
The new observations add support to a two-part explanation for Iapetus' appearance. First, as Iapetus treks around Saturn, its leading edge scoops up a thin coating of dark material, which amplifies sunlight absorption.
"Dusty material spiraling in from outer moons hits Iapetus head-on and causes the forward-facing side of Iapetus to look different than the rest of the moon," said Tilmann Denk, Cassini imaging scientist at the Free University in Germany.
Over time, as the black-ish surfaces warm, the rate of evaporation increases until finally all the surface ice in that region melts away. Infrared observations from the Cassini flyby confirm the dark dust material is approximately -230 degrees Fahrenheit (-146 degrees Celsius)--warm enough for the release of water vapor from the ice.
The water vapor formed then condenses on the nearest cold spot, such as along polar regions and icy areas at lower latitudes on the trailing side of the moon. In that way, the dark material loses the mixed-in ice and gets even darker, while the bright material accumulates more ice and gets brighter, in what the astronomers call a runaway process that leaves no gray area.
a 2 faced moon... is it a Gemini?
No it’s not a Gemini. It’s an Iapetus.
That’s Dr. Who to you, capish?
I say we rename it John Kerry
Saturn’s Moon Iapetus Is the Yin-and-Yang of the Solar System
jpl.nasa | September 12, 2007
Posted on 09/17/2007 1:10:17 PM EDT by LRS
Richard C. Hoagland has another finding about Iapetus (Saturn’s Moon)!
Aliens might have made it!
Posted on 02/08/2005 2:35:56 AM EST by Simmy2.5
Saturn’s moon reveals bulging equator
New Scientist | 10 January 2005 | Stephen Battersby
Posted on 01/10/2005 10:05:00 AM EST by holymoly
Saturn’s Moon Iapetus Shows a Bulging Waistline
NASA | 1/7/2005 | Staff
Posted on 01/10/2005 12:10:32 AM EST by Southack
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