Force from Sunlight on a Solar Sail

This lesson shows how a solar sail accelerates when pushed by both absorbed and reflected sunlight.

Absorbed and reflected sunlight combine both direction and amount to push on a sail.

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

Skip intro

Force from 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


  • Hit the spacebar or "Continue/Pause" to start/stop the animation.
  • The sail resets after travelling 100 m, or hitting the "Reset" button.
  • 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.