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

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

중력 렌즈

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

Doppler Effect

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

겉보기등급, 절대등급, 그리고 별까지의 거리 관계

Apparent Magnitude, Absolute Magnitude, and Distance to Stars

Star brightness and apparent magnitude Hipparchus of ancient Greece distinguished the stars in the night sky according to their brightness. He classified the brightest star as ‘magnitude 1’ and the darkest star as ‘magnitude 6.’ The … more

Stellar Parallax - 3D VR

Stellar Parallax – 3D VR

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

3D Location of the Ursa Minor(Polaris)

3D Location of the Ursa Minor(Polaris)

Constellations and distance to stars If you look at the sky where there is no light on a clear night, there are so many stars that can not count. Thousands of years ago, the ancients linked … more

Stellar Classification

Stellar Classification

Surface temperature and color of object When the iron is heated, it is initially dark red, but as the iron’s temperature rises, it gradually takes on a yellowish color. This is because the light emitted by … more

Parallax of Eyes

Parallax of Eyes

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

Stellar Parallax

Stellar Parallax

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

별자리

Constellations

Constellations If you look at the sky where there is no light on a clear night, there are so many stars that can not count. Thousands of years ago, the ancients linked stars to create constellations … more