## 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 measure the distance? Humans … 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 and the sun, the … more

## Earth’s gravity

Gravity Gravity is the force that is attracted between all objects with mass. According to Newton, an object with mass attracts each other with force proportional to the two objects’ mass and inversely proportional to the square of the distance … more

## Range and Intensity of the Gravity

Gravity Gravity is the force that is attracted between all objects with mass. According to Newton, an object with mass attracts each other with force proportional to the two objects’ mass and inversely proportional to the square of the distance … more

## Minimal force required for the lever

Lever A lever is a tool that transmits force using a rod. With a lever, you can work with it having little force. The length of the lever can adjust the minimum force required to move the lever. Work at … more

## ‘Work’ in science

‘Work’ in science ‘Work’ in science and ‘work’ in everyday life is a little different. In science, ‘work’ is to apply a force to an object and move it in the force’s direction. In the following cases, It is said … more

## 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 stars in between were … more

## 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 stars to create constellations … more

## Why does the moon seem to follow me?

Is the moon really following me? How can you explain that the moon looks follow I? The moon doesn’t follow me. For example, if I go forward with a car, the landscape seems to move backward. If the vehicle moves … more

## Pulleys with Many Wire

Movable Pulley Movable pulleys can move axes, unlike fixed pulleys. Movable pulleys have the advantage of being able to move with less force. But, the distance that I have to move is longer than the fixed pulley. So, there is … more

## Pulleys with One Wire

Movable Pulley Movable pulleys can move axes, unlike fixed pulleys. Movable pulleys have the advantage of being able to move with less force. But, the distance that I have to move is longer than the fixed pulley. So, there is … more

## 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 measure the distance? Humans … more