12.4.20. Sky

The sky is a transparent sphere with the sun, planets, moons and several stars.

When placed at the origin and given a time (via the .time parameter), all the bodies get placed in the right position for that moment. This allows knowing directions or displaying some of the celestial bodies. By default all the bodies are hidden. They can be displayed by setting the .hidden attribute to false, or placing newly-created objects in their positions.

Alternatively, it can cast shadows, by placing lights on them.

12.4.20.1. Attributes

  • .radius: The radius for the sphere. By default 20km
  • .origin: The point in which we are sitting
  • .color:
  • .scale: scale for the planets, relative to its real apparent size. Size is given in minutes?
  • stars.diameter: size for the stars (in angle?)

12.4.20.1.1. Elements

  • .sun: the sun
  • .moon: the
  • .mercury:
  • .venus:
  • .earth:
  • .mars:
  • jupiter:
  • saturn:
  • uranus:
  • neptune:
  • pluton:
  • ceres:
  • juno:
  • vesta:

There are other minor bodies as well.

12.4.20.2. Attributes for planets

  • .color: the color for each planet
  • .magnitude: the magnitude for the planet
  • .position: position
  • .plane: the ecliptic plane

12.4.20.3. Functions:

12.4.20.4. Examples:

Display the sky:

sky s:  .radius 30km .color