HR Diagrams
In the universe, there are many different types of stars. These stars are classified onto an chart. This chart is called the HR diagram. (Shown)
The HR diagram was created by Ejnar Hertzsprung and Henry Norris Russell. They formed this chart in the early 1900's. They classified the stars by their temperature against their luminosity. The blue and the white stars are the hottest, and the red, orange, and yellow stars are the coolest. The stars are then classified by their size. "Giants" and "Supergiants", "Main Sequence", and "dwarfs". Stars along the Main Sequence are the most common in size and temperature. The Sun, in which out Solar System rotates around, is found in the Main Sequence group of stars.
Spectral Classes
A stars spectrum is it's color, which is defined as is surface temperature. As discussed above, it a star is blue or white, then the star is very hot. These stars are among the hottest in the universe. If the star is yellow, orange,(hottest to coolest) then the star is among the coolest in the universe. The picture shows actual stars. The blue and red stars have tints to them. We cannot see the vivid color because they are so far away.
Quiz
1. What spectrum stars are the hottest?
2.What spectrum of stars are the coolest?
3.True or False: Main Sequence stars are the most common type of stars.
4.True of False: The Sun is found in the "Main Sequence" stars.
5.Complete the Sentence: Dwarf Stars are as/than the Sun.