Estimate
Helium in a common star
- Probability:
- 28%
- Odds:
- 1 to 2.6
- dBan
- −4.1 dBan
A representative common star is about 28% helium by mass.
Calculation
p ≈ 0.28 by mass
Assumptions
The NASA representative mixture is about 70% hydrogen, 28% helium, and 2% heavier elements by mass. The model samples equal-mass portions, not atoms. It is an approximate teaching composition, not an exact value for every star or an empirical aggregate of the whole galaxy.
Sources
- NASA: what are stars made of? representative 70% hydrogen, 28% helium, and 2% heavier-element mass mixture; checked 27 October 2026