what color the human eye see when people look at that star

the difference between how bright a star looks at two different wavelength regions

the total luminosity of the star in all parts of the electromagnetic spectrum

the amount of hydrogen in the atmosphere of a star

O

A

M

F

are located in many different regions of the Milky Way

have different temperatures

are made of significantly different elements

sometimes have atmospheres and sometimes do not

decreasing temperature

increasing mass

increasing amount of hydrogen

decreasing distance from us

Edwin Hubble

Annie Jump Cannon

Cecilia Payne

Joseph Fraunhofer

a brown dwarf

the Sun

an M-type dwarf

an O-type star

by seeing the luminosity of the star decrease as it moves away

by measuring the diameter of a star

by seeing the whole star become redder

by looking at the Doppler shift in the lines of the star's spectrum

all the stars and constellations would look exactly the same as they do now

all the stars we can see in the sky today will have died in a million years

because of proper motion, a number of the familiar constellations will look somewhat different in a million years

at the present time, astronomers do not know enough about the universe to say what the sky might be like in a million years

stars that rotate show a large Doppler Shift to only the blue end of the spectrum

stars that rotate have a much lower luminosity

stars that rotate have much wider absorption lines in their spectra

there is no way to tell if stars are rotating rapidly