*The Hertzsprung-Russell(H-R) diagram is a graph in which the temperature of stars is plotted against their brightness. The temperature of a star is indicated by its colour.
*Cool stars are red or reddish-yellow.
*Hot stars burn white or blue.
*Medium-sized stars from a diagonal bond called the main sequence across the graph.
*The whiter and hotter a main sequence star is, the brighter it shines. White stars and blue-white stars are usually bigger and younger.
*The redder and cooler a star is, the dimmer it glows. Coll red stars tend to be smaller and older.
*Giant stars and white dwarf stars lie to either side of the main sequence stars.
*The H-R diagram shows how bright each colour star should be. If the star actually looks dimmer, it must be further away.
*By comparing star's brightness predicted by the H-R diagram with how bright it really looks, astronomers can work out how far away it is.
*The diagram was devised by Ejnar Hertzsprung and Henry Russell.
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1000 Things You Should Know About Space
Non-FictionWhat is written here are facts and about true reasearch of SPACE
