Half of the universe’s ordinary matter is missing, astronomers say they’ve found it in a vast hydrogen cloud

Map of space microwave background. The circles indicate spots where ionized hydrogen scattered radiation.

Ordinary matter, the atoms that make up stars, planets, and living things, make up only about 15% of the total matter in the universe. The rest is thought to be due to dark matter, but it has not been directly detected. However, more than half of that 15% remains unexplained, leaving gaps in cosmological models. … Read more