Laboratory "Trace of Shadow"


  • The white circle represents the celestial sphere and the green circle represents the ground. The sun or a star make a round of yellow circle in a day.
  • If you want to see the rough scketch of the curve in north pole in summer, set "Latitude of observatory = 90 degrees" and "Latitude of the star = 25". Then press "Animation" button. You will see a circle.
  • If you want to see the rough scketch of the curve in Tokyo in summer, set "Latitude of observatory = 35 degrees" and "Latitude of the star = 25". Then press "Animation" button. You will see a hyperbola.




Check "Cones". Then you will understand what is the curve of the trace.