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 … more
Astronomy Simulation
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 … more
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 … more
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 … more
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, … more
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 … more
Gravitational Lensing
Space-time warpage Einstein, famous for the theory of relativity, thought that the mass of an object warps space-time. The larger the mass, the greater the degree of time-space warp. He explained that an object’s falling or … more
Phase of the Moon 2
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 … more
Foucault Pendulum (WebGL)
Foucault’s pendulum is a device invented by French scientist Leon Foucault to prove the Earth’s rotation in 1851. The fact that the Earth rotates has been known for a long time, but it is the first … more
Kepler’s law
Kepler and Tycho Brahe There is an astronomer before talking about Kepler (Johannes Kepler 1571 ~ 1630). That’s Tycho Brahe. Tycho Brahe (1546-1601) is a famous Danish astronomer. With the development of astronomical equipment, he left … more
Doppler Effect
Doppler Effect We have heard an ambulance siren and felt that the ambulance is getting closer. When the ambulance approaches, the sirens sound higher, and when they move away, the sirens sound lower. That is, when … more