Alright! So you got me, I don’t often ask myself that question, because to be perfectly honest with you, I never heard the term “baryons” before last week. However, it does look like missing matter of the universe has been found…or, to put it more precisely, at least 50% of the missing “normal” matter has been found, also known as baryonic matter, in the spaces between the galaxies. So I suppose that means that since baryonic matter makes up only 5% of total matter in the universe…we are still in fact missing 95% of all matter?
Baryons are protons, neutrons, and other subatomic particles that make up ordinary matter such as hydrogen, helium and heavier elements. Baryonic matter forms stars, planets, moons and even the interstellar gas and dust from which new stars are born, said Shull. Astronomers caution that the missing baryonic matter is not to be confused with “dark matter,” a mysterious and exotic form of matter that is only detected via its gravitational pull.
Interview of Mike Skull, CU-Boulder Professor on Skeptics Guide to the Universe podcast.