Electrons are lazy. They don't want to do any more work than they have to. So, when they're in an atom, they're generally in the lowest possible energy level that they can occupy, called its "ground state," which translates roughly to doing the bare minimum amount of work to get by (I can relate!) But, when you apply some energy to that atom, the electron gets excited and jumps out to a higher energy level. In order to do this, the electron has to absorb some of that energy to get it out there. After a while, the electron decides it's tired of working that hard, and moves back to its ground state where it's supposed to be. At that point, the electron gives back that energy it absorbed in the form of a "photon," a bundle of light energy. Billions and billions of photons make a visible light of a certain wavelength that we can see. This is how neon lights work.
the gases that make up most stars are so hot that they glow and give off their own light. that's why they are said to be luminous.
nuclear fusion
phosphor
Blue stars are more luminous than other main sequence stars but not necessarily brighter than giant and supergiant stars.
stars
Red Giants
from my text book: "The most luminous stars are so rare you find few in your survey region. There are no O stars at all within 62 PC of Earth. Lower-main-sequence M stars, called red dwarfs, and white dwarfs are so faint they are hard to locate even when they are only a few parsecs from earth."
stars, flames, bulbs, the sun
An irregular luminous band of stars is called a galaxyof stars.
Stars are luminous, shine by themseves. Moon isn't, it can only reflect light.
Blue stars are more luminous than other main sequence stars but not necessarily brighter than giant and supergiant stars.
Strictly speaking, no; stars are incandescent (light resulting from heat) as opposed to luminscent (light resulting from non-thermal based effects). One might, however, safely describe stars as "luminous" in a metaporical sense.
Generally, the more massive a star is, the more luminous they are. The most luminous stars appear blue.
luminous
All things, except black holes, are luminous. That includes stars. You might think that some other things are not luminous but that's because you can't see the kinds of light that they emit.
Technically, no nebulae are luminous. The ones that appear as such have stars either within or near them, and the nebulae merely reflect the light emitted by these stars.
A star is a massive, luminous ball of plasma.
sun, stars, CD,
stars
stars