Force from Reflected Sunlight on a Solar Sail

This lesson shows how a solar sail accelerates when pushed by the reflected sunlight.

Reflected light pushes back on the sail in the opposite direction that it shines.

The force is proportional to the amount of light reflected.

Tilting the sail reduces the amount of sunlight reflected, and changes the direction of reflection.

The arrows show the direction and amount of:
Acceleration & force
Velocity & speed

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Force from Reflected Sunlight


Sun incidence 0 deg
Rotation about sun 0 deg
Acceleration 1 mm/s 2
Speed 0 mm/s
Distance 0 m
Time (100X) 0 min:sec


  • The sail resets after travelling 100 m, or hitting the "Reset" button.
  • Hit the spacebar or "Continue/Pause" to start/stop the animation.
  • Keyboard and Mouse:
    • Zoom by rolling the mouse wheel up and down, or holding the middle mouse button and moving up and down.
    • Rotate the view by holding the left mouse button, and moving the mouse left, right, up, and down.
    • Tilt the sail by pressing the up and down arrow keys.
    • Rotate the sail by pressing the left and right arrow keys.
  • Touchscreen:
    • Zoom in and out by putting two fingers on the screen and pinching or spreading them apart.
    • Rotate the view by sliding one finger left, right, up, or down.
    • Tilt the sail by tapping the yellow up and down arrows.
    • Rotate the sail by tapping the yellow left and right arrows.
  • Reload to see the introduction again and change the target.