Are there sand dunes on other planets?

Yes, wind-blown dunes are common on Mars and exist on Venus and Titan, and some Martian dunes are still active today.

Does it rain on Titan?

Yes, but with liquid methane rather than water; Titan has methane clouds, rain, rivers, and lakes that carve and fill its surface much as water does on Earth.

Aeolian and Fluvial Surface Processes

Erosion, transport, and deposition by wind and flowing liquids that carve dunes, channels, and sedimentary landscapes on planets and moons.

Definition

Aeolian and fluvial surface processes are the erosion, transport, and deposition of material by wind and by flowing liquids, respectively, that shape planetary surfaces.

Scope

This topic covers the gradational processes driven by moving fluids on planetary surfaces: wind-driven (aeolian) transport that forms dunes, ripples, ventifacts, and dust storms, and liquid-driven (fluvial) processes that carve valleys, channels, and depositional fans. It treats the physics of sediment entrainment and transport under different gravities and atmospheres, and it spans terrestrial analogs, the active dunes and ancient river networks of Mars, and the methane rivers and dunes of Titan.

Core questions

How do wind and flowing liquids entrain and transport sediment under varying gravity and atmosphere?
What landforms diagnose past or present wind and liquid activity on a planet?
What do Martian channels and Titan's rivers reveal about past climates and liquids?
How do these processes differ across worlds with different fluids and conditions?

Key theories

Sediment entrainment and saltation: A fluid moving over a surface lifts and bounces grains once it exceeds a threshold stress, and the resulting saltation builds ripples and dunes whose form depends on gravity, fluid density, and grain size.
Fluvial landform interpretation: Valley networks, outflow channels, and depositional fans record the past or present action of flowing liquid, allowing reconstruction of climate and surface conditions on bodies such as Mars and Titan.

Mechanisms

When wind or flowing liquid exerts enough shear stress, grains are entrained and transported by saltation, suspension, or bed load, then deposited where the flow weakens, forming dunes, ripples, channels, and fans. The thresholds and resulting forms depend on the local gravity, the density of the moving fluid, and the available sediment, which differ markedly among Earth, Mars, Venus, and Titan.

Clinical relevance

Aeolian and fluvial landforms record a planet's climate history and the past presence of liquids, making them key evidence for reconstructing surface conditions and assessing habitability, as in the search for ancient water on Mars.

History

Bagnold's foundational studies of wind-blown sand on Earth were extended to other worlds as spacecraft revealed dunes on Mars and Venus and the river networks and valleys of Mars. Cassini-Huygens later found vast dune fields and methane rivers and lakes on Titan, confirming that wind and liquid shape surfaces across the Solar System under very different conditions.

Debates

Volume and duration of liquid water on early Mars: How much liquid water flowed on Mars and for how long, inferred from its channels and fans, is debated and bears directly on its past climate and habitability.

Key figures

Ronald Greeley
Ralph Bagnold
James Iversen
Michael Carr

Seminal works

greeleyiversen1985
melosh2011

Frequently asked questions

Are there sand dunes on other planets?: Yes, wind-blown dunes are common on Mars and exist on Venus and Titan, and some Martian dunes are still active today.
Does it rain on Titan?: Yes, but with liquid methane rather than water; Titan has methane clouds, rain, rivers, and lakes that carve and fill its surface much as water does on Earth.