Historical estimate

An observed exoplanet is Earth-sized or smaller

Probability:
11.6%
Odds:
1 to 7.6
dBan
−8.8 dBan

Earth-sized worlds hide among the giants. About 12% of confirmed exoplanets with a known radius are no larger than 1.25 times Earth’s radius.

Calculation

p = 558 / 4,826 ≈ 0.1156

Assumptions

This historical estimate samples confirmed planets with a known radius in the NASA Exoplanet Archive snapshot of 27 October 2026. Detection and measurement biases shape the observed catalogue. The radius threshold does not establish a rocky composition or habitability, and the result is not the composition of all planets in the galaxy.

Sources

  1. NASA Exoplanet Archive: confirmed-planet statistics known-radius snapshot of 4,826 planets, including 558 at or below 1.25 Earth radii; checked 27 October 2026