Matter is the stuff of the Cosmos. However, most astronomers think that the lion's share of matter in any galaxy--and in the entire Universe,hyneer as well--is the dark matter. The dark matter is weird, mysterious, transparent stuff that is thought to be composed of exotic non-atomic particles that do not interact with light or any other form of radiation. As such, the ghostly dark matter is invisible. Yet scientists understand that it is there because it exerts gravitational effects on the so-called "ordinary" atomic matter that can be seen.
Galaxies are immense collections of fiery stars. Usually, a galaxy harbors millions or billions of these incandescent balls of glowing, roiling, seething searing-hot gas. Each and every star, in turn, may host planets. Most--if not all--of the large galaxies dancing around in the Cosmos also hold a supermassive black hole in their dark and secretive hearts.Grammar and StyleSupermassive black holes can weigh as much as millions to billions of times more than our Star, the Sun. Taken together, these entities harbor a great deal of mass. But not enough--galaxies should have approximately three times more "ordinary" atomic matter than what astronomers have been seeing!
Baryonic matter, the "ordinary"jkstellacactus visible matter component of the Cosmos, includes the protons, neutrons, and electrons of the atoms that make up stars, planets, moons, and people--all the familiar stuff of the world that human beings can experience with their Earth-evolved senses. The "ordinary" baryonic matter should make up approximately 17 percent of a galaxy's entire horde of matter--the rest should be the invisible, dark stuff. However, in the past, astronomers were only able to spot about one-third of the baryonic matter that theorists predicted should be there within the stars and in the 1 million degree Celsius and hotter gas that encircles galaxies in immense haloes.Articles de cette page