Distance of 1 pc(parsec)
2023.5.24 Update: Improved execution speed by modifying the algorithm. 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...
Astronomy Simulation
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 sun illuminates the northern...
Phase of the Moon 3
It is only the sun that shines by itself in the solar system. Earth and moon do not emit light themselves. The earth and the moon only reflect the light of the sun. Since the earth and the moon have...
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 only after reflection by...
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 Sun, Earth & Moon...
Real Size & Orbit of Earth and Moon
The photographs of the Earth and the moon close together that you can see on posters, etc., are designed to be easy to see. The moon’s apparent diameter is only about 0.5˚. This tells us that the Earth and the...
Newtonian Reflector
Refracting telescope A telescope that uses only the refraction of a lens is called a refracting telescope. There are two types of refracting telescopes depending on the combination of lenses. The Galilean telescope is often referred to as a terrestrial...
Refracting telescope (Keplerian, Galilean)
Refracting telescope A telescope that uses only the refraction of a lens is called a refracting telescope. There are two types of refracting telescopes depending on the combination of lenses. The Galilean telescope is often referred to as a terrestrial...
Eclipse
Solar eclipse Eclipse is the phenomenon that one object hides another object or enters that shadow. ‘a solar eclipse’ is the moon’s phenomenon covering the sun. Lunar eclipse When the moon enters the shadow of the earth, it becomes ‘the...
Solar System
Solar System All the orb bodies that revolve around the sun and their space are called the solar system. The celestial bodies that make up the solar system include the eight planets revolving around the sun and the sun, the...
Eratosthenes’ Calculation of Earth’s Circumference 2
Eratosthenes’ Calculation of Earth’s Circumference The first person to measure the earth’s size was Eratosthenes, an ancient Greek scientist about 2,000 years ago. Eratosthenes lived in Alexandria, near the Nile River’s mouth by the Mediterranean coast, in northern Egypt. He...
Geocentrism vs. Heliocentrism
Geocentrism, The Geocentric theory The Geocentric theory is a cosmic perspective in which the Earth is at the center, and all the stars revolve around the Earth. From the 13th to the 17th century, it was a widely recognized worldview...
