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Jump27of 100 · 1,290 M km from Earth

Iapetus: one black face and one white

Iapetus, a moon of Saturn, has one face as dark as coal, one bright face and a 10 km mountain ridge around its equator. Facts with sources.

The two faces of Iapetus, one dark and one bright, in two Cassini photos placed side by side
Image: NASA/JPL/Space Science Institute · original

Curious facts

  1. Two faces

    The face that leads in its orbit is as dark as coal and the trailing one is much brighter: it reflects more than ten times as much light (my own sum, from NASA’s figures). 1

  2. A ridge around the equator

    A chain of mountains about 10 km high circles its equator. How it formed is still unclear. 12

  3. Why one face is black

    NASA points to two causes. Iapetus may be sweeping up dark dust from Phoebe, a more distant moon. And the dark side, which warms up more, loses its ice: it evaporates and ends up on the bright side. 1

Iapetus in Orbit

In the game, Iapetus is jump 27 of the route, 1,290 M km from Earth. Its logbook card says:

Logbook · Jump 27

One side is coal-dark, the other snow-bright

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What Orbit is like

Sources

  1. NASA, Iapetus. science.nasa.gov/saturn/moons/iapetus
  2. Wikipedia, Equatorial ridge on Iapetus. en.wikipedia.org/wiki/Equatorial_ridge_on_Iapetus

Checked between 8 and 11 October 2026.

Image: NASA/JPL/Space Science Institute · original