Remember that stars in the sky like our Sun
are just giant balls of burning gas floating in outer space.
When scientists want to measure how hot a star is,
they use something called stellar classification.
The letters for stellar classification from hottest to coldest are:
O, B, A, F, G, K, M.
That can be tough to remember, so you can think of it with this sentence:
Oh Be A Fine Girl Kiss Me since those first letters all match up.
A stars heat usually makes it burn a type of color,
so each of the letters has a color that goes with it.
O - blue
B - blue white
A - white
F - yellow white
G - yellow
K - orange,
M - red
Scientists like to use the letters for how hot the star is,
but sometimes it's more fun to talk about a star by it's color!
(from: wikipedia - stellar classification)
