About starsStars are cosmic energy engines that produce heat, light, ultraviolet rays, x-rays, and other forms of radiation. They are composed largely of gas and plasma, a super heated state of matter composed of subatomic particles. No one knows how many stars exist, but the number would be staggering. Our universe likely contains more than 100 billion galaxies, and each of those galaxies may have more than 100 billion stars.
|
Some stars have always stood out from the rest. Their brightness is a factor of how much energy they put out, which is called their luminosity, and also how far away from Earth they are. Stars in the heavens may also appear to be different colors because their temperatures are not all the same. Hot stars are white or blue, whereas cooler stars appear to have orange or red hues.
-see more at http://science.nationalgeographic.com/science/space/universe/stars-article/ |