How Powerful A Force: Star Wars And Sand Dune Dynamics

Image by Rosino at Wikipedia

Long long ago in a galaxy far far away, Our Heroine ran away from home in a landspeeder determined to make it to the Big City for a chance at a cosmopolitan life. Rather than being caught by sand raiders or droid dealers, she got lost because her landmarks—off a map bought from an old man who hadn’t left his house in years—had moved.

Our heroine stares at the sand, sand, and more sand surrounding her. As she looks, the sand resolves into crescent-shaped dunes, a stone plateau. Straight before her lies the slack of a dune, the lowest point from its crest, falling into shadow as the afternoon sun lowers. She has left behind the desert steppe of her aunt and uncle’s home, with its torrents of summer rains and the scrub plants hugging the ground to avoid erosion by the wind. There is only wind here: no calls of drought-tolerant birds or foxes yipping at their kits.

What’s our heroine to do? She’s not an aeolian geomorphologist but she’s lived in the desert her whole life and she understands how powerful a force the wind is. The wind scours existing rocks, blasting them into minuscule particles. It grabs those particles and hurls them, letting go its grip only at a distance dependent on the particle size and the wind’s energy. The wind here is a constant roar. She realizes small particles do plenty of damage pitched into her eye or the speeder’s engine at even low wind speeds. To her left and right are two yardangs, wind-sculpted rocks ten metres high, whose twisted and eroded silhouettes mark this as the boundary of the true desert, reminding her she cannot stand here thinking forever.

As she hesitates, the slack before her thumps full, the sand on the windward side of the dune’s crest crashing down, avalanching over the peak and spilling into the slack. Fine particles rise up, filling the air and billowing out. Our heroine coughs, wraps her djellaba tighter over her mouth and nose. She can no longer tell where the dune was, its crescent snaking into the next. The map is useless. The dunes will have moved ten metres a year for each year the old man hid from the universe. She bets even the bar locations, fastidiously drawn in, will have shifted by the time she arrives. Only eagle-eyed, or satellite-eyed, could she see her way to the city, ignoring the landscape.

She looks up in despair, to find the first stars coming out. Moisture-vaporator farm girl that she is, she’s no stranger to astronomy. She settles into the landspeeder, headlights on full, holding her hand beneath her eyes to shade them as she takes her bearings: there’s Vega. Drive, straight through until morning in that direction (accounting for the planet’s rotation), and she’ll find the city.

First bar past the gate guards, she plugs in her handheld and finds “Dunes on planet Tatooine : Observation of Barchan Migration at the Star Wars film set in Tunisia” in her inbox, sent from her aunt, accompanying a video from her worried and angry uncle demanding she come back right now. Reading it, she realizes just how lucky she was to arrive safely. Time now to find herself a light saber.

//Image by Rosino at Wikipedia, used under Creative Commons Attribution-Share Alike 2.0 Generic.

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