Estimate
Hydrogen or helium in a common star
- Probability:
- 98%
- Odds:
- 49 to 1
- dBan
- +16.9 dBan
Almost all of a representative common star is just two elements: about 98% hydrogen or helium by mass.
Calculation
p ≈ 0.70 + 0.28 = 0.98 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