The relationship between stars and constellations: constellations are the combination of stars in the sky. Constellations are made up of stars.
Nebulae contain almost all expandable objects except planets and comets. Their main component is hydrogen, followed by helium, and they also contain a certain proportion of metallic elements and nonmetallic elements.
In ancient times, the rise and fall of stars or constellations were often used to navigate and determine time. Ancient Egypt determined the beginning of a year by observing the rise of Sirius. In some areas, the ancient technology of determining position by observing stars still remains. Constellations and the literary images they represent often appear in the works of literati.
Although the importance of constellations has been relatively reduced in modern times, they have not lost their charm for astronomy lovers. Through its fascinating legend, constellations have played an extremely important role in the popularization of astronomy. Whenever there is a major astronomical phenomenon, astronomers, popular science workers and the media will always set off an astronomical upsurge in society, especially among young people.
Extended data:
Interstellar matter is closely related to the evolution of celestial bodies. Observations have confirmed that interstellar gas is mainly composed of hydrogen and helium, which is the same as that of stars. In fact, stars are "condensed" by interstellar gas. Interstellar dust is a small solid substance, which is composed of carbon compounds, oxides and so on.
The distribution of interstellar matter in space is not uniform. Under the action of gravity, gas and dust in some places may attract each other, become dense and form clouds. People vividly call them "nebulae". According to the morphology, the nebulae in the Milky Way can be divided into diffuse nebulae and planetary nebulae.
Compared with stars, nebulae have the characteristics of large mass, large volume and low density. The mass of an ordinary nebula is at least equivalent to thousands of suns, and the radius is about 10 light-year.
References:
Baidu encyclopedia-Polaris
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Baidu encyclopedia-constellation
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Baidu encyclopedia-nebula