Ordinary matter in the universe, which is composed of atoms and is responsible for the formation of stars, planets, and other celestial objects, is primarily found in the following locations:
-
Stars: Most ordinary matter is concentrated in stars, which are massive celestial bodies that generate energy through nuclear fusion. Stars account for a significant portion of the total baryonic (ordinary) matter in the universe.
-
Interstellar Medium: Between stars, there are vast amounts of interstellar gas and dust, collectively known as the interstellar medium (ISM). This matter consists mostly of hydrogen and helium, along with trace amounts of heavier elements.
-
Planets and Moons: Ordinary matter also exists in the form of planets, moons, asteroids, and comets, which are formed from the residual material that did not become part of stars during the formation of solar systems.
-
Galactic Structures: Ordinary matter can also be found in galaxies and their structures, including stars, gas clouds, and dust within the galaxy.
Regarding dark matter and dark energy:
-
Dark Matter: This is a non-luminous form of matter that does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects. It is believed to make up about 27% of the universe's total mass-energy content and is thought to be distributed throughout galaxies and clusters of galaxies.
-
Dark Energy: This is a mysterious form of energy that is driving the accelerated expansion of the universe. It is believed to make up about 68% of the universe's total energy content and does not have a known counterpart in ordinary matter.
In summary, while most ordinary matter is found in stars and interstellar gas, a significant portion of the universe's mass-energy content is made up of dark matter and dark energy, which are not directly observable but play crucial roles in the structure and evolution of the universe.