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 the ball were moving, … more
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 measure the distance? Humans … more
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 planet’s revolution is a … more
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 an ambulance approaches with … more
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 stars in between were … more
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 measure the distance? Humans … more
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 stars to create constellations … more
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 the iron changes as … more
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 measure the distance? Humans … more
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 measure the distance? Humans … more
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 named after animals, objects, … more
