ODLUCULUP
a. What is a star's spectrum? Which spectrum is most common in stars? How can it differ from star to star?
What does the spectrum tell us about the star?

a. What is a star's spectrum?

A star's spectrum refers to the "amount of light" that stars they give off according to varying wavelengths. Since we cannot tell the amount of light a star gives off quantitatively from Earth, we can differentiate them according to how bright they appear.

b. Which spectrum is most common in stars?

Stars are classified according to their spectra (elements in the star). They are classified into 7 types (O, B, A, F, G, K and O). The most common type is M, however, it gives off a dim light.

c. How can it differ from start to star?

Although stars follow a continuous spectrum, the spectra of a star differs from each other because they do not give off the same amount of energy at the different wavelengths.

d. What does the spectrum tell us about the star?

The spectrum can tell the surface temperature of the star. This means that a blue star (we often see it as a white-colored star from Earth) is hotter than that of a yellow star. A red star is considered the coolest star among all.

The spectrum of stars also allows the astronomers to study composition of the stars according to their wavelengths.

c should be the answer