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By observing the motions of stars within galaxies AND the warping of space between galaxies, we can only conclude that there is SOMETHING creating gravitational effects in both these areas. Whatever this "something" is, its mass density throughout the galaxy is about six times that of the baryons we know about. This something can NOT be more baryons (which make up stars, even brown dwarf ones), because that high a density of baryons, early in the history of our Universe, would have resulted in so much nuclear fusion just after the Big Bang that no hydrogen would have been left to create stars. Indeed, the fact that the ratio of hydrogen to helium in our Universe is almost exactly what it should be, if baryon density was what we calculate it was just after the Big Bang, is a major reason Big Bang Cosmology is the only accepted cosmological model today.
This something also can not be charged leptons, as this would create a vast charge buildup in our Universe.
Thus, this "something" creating gravitational effects consists neither of baryons nor of leptons. So what is it? We don't know! -- which is why we call it "dark" matter.
What else can I help you with?
Stars are made up of?
Stars are mostly composed of hydrogen and helium.
What element are stars mostly composed of?
hydrogen,All stars are composed primarily of hydrogen. Stars can also contain some other elements such as helium, but hydrogen accounts for the majority of a star's composition.
What are elements called that make up a star?
Stars are composed mostly of hydrogen and helium.
Are gold atoms composed of mostly matter or empty space?
All atoms are mostly empty space, as the electromagnetic repulsion between atomic nuclei keep them from reaching each other (except under extreme pressure, as in the center of stars).
Which type of galaxy is composed mostly of young stars?
The spiral galaxy's.
The state of matter of the interior of the sun and other stars?
The state of matter is mostly gas and plasma (free moving atomic parts).
What is the chemical composition of most stars?
Most stars are composed primarily of hydrogen and helium, with hydrogen making up about 75% of their mass and helium about 25%. The remaining elements in stars are present in trace amounts, including carbon, oxygen, nitrogen, and other heavier elements.
What of these is composed of stars?
The "Hollywood Walk of Fame" is composed of stars.
What is a very hot gas-like state of matter made up mostly of charged particles?
Plasma is the very hot gas-like state of matter made up mostly of charged particles. It is composed of ions and free electrons and is considered the fourth state of matter, in addition to solid, liquid, and gas. Plasma is common in stars, lightning, and some man-made technologies like plasma TVs.
How much matter is composed of plasma?
About 99% of the matter in the universe is composed of plasma, which is a state of matter that consists of partially ionized gas. Plasma is found in stars, such as the Sun, and in other high-energy environments like lightning bolts and fluorescent light bulbs.
What is something mostly hydrogen some helium?
A star is mostly composed of hydrogen and some helium. The fusion of hydrogen into helium is what produces the energy and light that stars emit.
What are some properties of matter?
Matter is defined as anything that has mass and occupies a volume. It can be in four states: Solid, Liquid, Gas, or Plasma (Like in the Stars, or the Sun). All matter is composed of atoms.
