2020-09-30

Why are the colors of the stars different?

By yqqlm yqqlm

Did you know that both planets and stars have their own unique colors, and the colors of planets may depend on the concentration of the atmosphere. For example, Mars and Mercury, which have a thin atmosphere, show their own colors; while the atmosphere is relatively The dense Venus, Jupiter, Saturn, Uranus, and Neptune bring colorful colors to them based on atmospheric composition and effects such as reflection and absorption.

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Stars are different from planets. Some brighter stars are easy to distinguish. Darker stars also have different colors, but they are not easy to distinguish. The color of a star depends on the temperature of the surface of the star. From the spectrum of the star, different colors represent different temperatures, some are reddish, and some are blue. The bluish stars have higher surface temperatures, such as Betelgeuse, Xuanyuan 14 and Shui Weiyi, with surface temperatures above 25000K. Red stars have low surface temperatures, such as Betelgeuse and Antares, with surface temperatures of 3600-2600K.

In addition to planets and stars, there are countless nebulae, galaxies and other celestial bodies in the universe. These nebulae and galaxies are also an important part of the color of the starry sky. The red nebula is an emission nebula, which is excited by the intense ultraviolet radiation of surrounding O-type and B-type stars. The red color comes from hydrogen radiation, the green light comes from oxygen, and the yellow and brown colors come from sulfur and other ions. Blue nebulae are reflection nebulae. The stars around them don’t have enough radiation to ionize and glow, but they are enough to make them shine due to reflection. The blue light is largely scattered by the material particles in the nebula, and most of the red light can be transmitted.

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It can be seen that each celestial body has a different color composition. It is the interaction between them that let us see the beautiful and dreamy starry sky. Facing the vast universe, there are more celestial mysteries waiting for us to explore and discover.

This article is scientifically checked by Li Liang, deputy editor of Beijing Planetarium.

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This work is the original”Science China-Science Principles Made Easy”, please indicate the source when reprinting.