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How did Miranda's large canyons form?
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Uranus
Two views of the southern hemisphere of Uranus, produced from images obtained by Voyager 2 on Jan. 17, 1986. In colours visible to the unaided human eye, Uranus is a bland, nearly featureless sphere (left). In a colour-enhanced view processed to bring out low-contrast details, Uranus shows the banded cloud structure common to the four giant planets (right). From the polar perspective of Voyager at the time, the bands appear concentric around the planet's rotational axis, which is pointing nearly toward the Sun. Small ring-shaped features in the right image are artifacts arising from dust in the spacecraft's camera.
The formation of the large canyons on Miranda—the innermost and most topographically varied of Uranus’s major moons—remains a subject of scientific study. While these riftlike canyons imply significant surface extension and fracturing, the exact cause of the moon's extreme geological activity is not definitively known.12
Current theories regarding the origin of these features include:
- Internal Expansion: It is hypothesized that Miranda may have experienced a volume expansion of approximately 6 percent. This could have occurred if the moon's interior water was once liquid and subsequently froze after the crust had already formed. As the water froze under low pressure, it would have expanded, stretching and shattering the surface.2
- Extrinsic Forces: The varied terrain might have resulted from one or more shattering collisions during the moon's early history.12
- Intrinsic Forces: The features could be the result of past tidal heating, which may have triggered eruptions from the moon's interior, similar to the volcanic activity observed on Jupiter’s moon Io.1
Ultimately, whether these features reflect a heterogeneous origin, a giant impact, or unique internal eruptions remains to be determined.12