When the weather is fine, you can see the stars at night. Why can't you see the stars during the day?

When the weather is fine, you can see the stars at night. Why can't you see the stars during the day? Stars are known to all. When the weather is clear, there will be stars in the sky, but there will be many stars in summer, but they usually appear at night and can't be seen at all in broad daylight. Then why? Let's use constellation knowledge to announce the reason why we can't see the stars in broad daylight.

In broad daylight, some light sources in the sun are transmitted by the air of the earth, making the sky very bright. There are many stars in the brightness of the sun, so people can't see them. If there is no air, the sky is dark. Even if the sun is more obvious, you can still see the stars.

Stellar chromaticity

There are two key factors that determine whether a star is bright or dark:

One is because of the luminous capacity of the star, and the other is the distance between the star and us.

Scientists generally divide the luminous power of stars into 25 magnitudes, and the difference between the strongest luminous power and the worst luminous power is about 65.438+0 billion times.

Stars that are close to everyone have strong luminous ability, so everyone will light up when they see them. However, even a star with very strong luminous ability, if it is far away from everyone, its chromaticity may not be better than a star with tens of thousands of times worse luminous ability.

The brighter the star, the smaller the magnitude. One of the most commonly used magnitude system software is three-color system software: U (ultraviolet), B (blue) and V (yellow). It can be determined that the visual magnitude M=+4.83, the color index value B-V=0.63, and U-B=0. 12. The color temperature can be clearly defined by the color index value.

For example, there is a planet called Antares. Its volume is about 220 million times that of the sun, and its luminous capacity is about 5000 times that of the sun. But because it is 465,438+billion light years away from the earth, everyone can only see that it is a bright star shining with colorful light. If you move Antares to the part of the sun, its light and heat will bake the earth into a Panyu boulder, and everything will disappear.