speed gun

Principle of Speed Gun

Doppler effect Electromagnetic waves (or sound waves) come into contact with another object while traveling; part of the wave is absorbed or reflected. A moving ball likewise absorbs or reflects some of the incoming waves. If … more

Day and Night, Seasons, White Night, Polar Night

Day and Night, Seasons, White Night, Polar Night

* 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. Day and night The … more

Phase of Moon

Phase of the Moon

* 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

Diurnal Motion and the Zodiac

The Diurnal Motion and the Zodiac

* 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 If you … more

Diurnal Motion (WebGL)

Diurnal Motion (WebGL)

* 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

Diurnal Motion of Sun

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

Distance of 1 pc(parsec)

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

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

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

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

Tides Simulation

Tides

Tide is a phenomenon that the ocean surface’s periodic rise and fall due to the moon and sun’s gravitational pulls. Spring Tide is the highest high tide that occurs during the tide. It occurs when the … more