Diurnal Motion of Sun
* If you are asked to access your location, please allow it. * Your personal data is not stored on the server. * For iOS devices, please allow location access as follows. Diurnal Motion Fix the … more
Astronomy Education
Distance of 1 pc(parsec)
Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you … more
Earth’s Revolution and Seasons (WebGL)
Earth Rotation and Seasonal Changes The Earth’s rotation axis is tilted at an angle of about 23.5 ° to the orbital axis. Because of this inclination, seasonal changes occur like spring, summer, autumn, and winter. The … more
Phase of the Moon 3
* If you are asked to access your location, please allow it. * Your personal data is not stored on the server. * For iOS devices, please allow location access as follows. It is only the … more
Cassegrain Reflector
Cassegrain Reflector The Cassegrain reflector(telescope) was designed by French engineer Laurent Cassegrain to compensate for the shortcomings of the Newtonian telescope. Light reflected by the concave mirror is incident on the convex mirror. Focus is created … more