Most ordinary matter is plasma
In stars, and in much of the gas between them, atoms are ionised. Plasma is the state of most ordinary matter in the universe.
A plasma is a gas of ions and free electrons, overall neutral, conducting, and responsive to magnetic fields. The Sun is plasma. So are the other stars, which hold nearly all ordinary mass. The interstellar and intergalactic medium is mostly ionised as well, a thinner plasma. Neutral gas, planets, and dust are the exception, gathered in cold corners.
The usual figure is that more than 99 percent of ordinary matter is plasma. The exact percentage depends on what you count as 'ordinary' and on how you treat the cold clouds. The direction of the inequality is not in doubt. On Earth, plasma is the exotic state, which is why it feels like a category error to call it the common one.
Caveats
- This excludes dark matter, which is not known to be ordinary plasma and is a separate entry.
- 99 percent is an order-of-magnitude statement from astrophysical inventories, not a weighed sample.
Sources
- 1Chen F. F.. Introduction to Plasma Physics and Controlled Fusion. Springer, 2016.