Astronomy Picture of the Day - Saturns Iapetus: Moon with a Strange Surface

APOD.NASA.gov ^ | 26 Feb, 2023 | Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

[MtnClimber]

Explanation: What would make a moon look like a walnut? A strange ridge that circles Saturn's moon Iapetus's equator, visible near the bottom of the featured image, makes it appear similar to a popular edible nut. The origin of the ridge remains unknown, though, with hypotheses including ice that welled up from below, a ring that crashed down from above, and structure left over from its formation perhaps 100 million years ago. Also strange is that about half of Iapetus is so dark that it can nearly disappear when viewed from Earth, while the rest is, reflectively, quite bright. Observations show that the degree of darkness of the terrain is strangely uniform, as if a dark coating was somehow recently applied to an ancient and highly cratered surface. Last, several large impact basins occur around Iapetus, with a 400-kilometer wide crater visible near the image center, surrounded by deep cliffs that drop sharply to the crater floor. The featured image was taken by the Saturn-orbiting Cassini spacecraft during a flyby of Iapetus at the end of 2004.

[Pete from Shawnee Mission]

View larger. | A selfie of the Chinese Mars rover Zhurong (center), with its lander (right), taken by the deployable Tianwen-1 Remote Camera on August 30, 2021. Image via China News Service/ YouTube/ Wikimedia Commons. Has the rover's

From EarthSky email: "Chinese Mars rover not moving. Is it kaput?

The Chinese Mars rover Zhurong appears not to have moved for about 6 months. Has its mission ended? There's been no official word about the rover from CNSA - the Chinese space agency - since May of 2022. That's when the rover entered a dormant state in anticipation of a long, cold and dusty Martian winter. Has the mission ended?

Comment: It appears the Chinese modeled their Martian rover on a Giant Chicken. Perhap the hope was to determine if a domed poultry farm could be set up to support a future Mars colony! The Lander was built to resemble a giant waterbug, a tasty source of fast growing protein! (Yes my comment is satire!)

[SunkenCiv]

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[Telepathic Intruder]

My bet is on tidal deformation.

[telescope115]

Could be…. I’m no planetary geologist.

[minnesota_bound]

Looks like a walnut.

[MtnClimber]

I know. Really strange.