Oars for the air of the sky

I originally did the planet, rings, and moon for Simple Photorealism using Persistence of Vision. When I wrote Silver sail and gold, above a dappled sea I added some Greek rowing ships.

Produce ships and sails which can be used in the air of the sky. Then you’ll find men to man them, men not afraid of the vast emptiness of space. — Johannes Kepler (Letter to Galileo)

When the light turns green you go.
When the light turns red you stop.
But what do you do when the light turns blue,
with orange and lavender spots? — Shel Silverstein (A Light in the Attic)