Almost 1,700 Earths in volume. Just 25 in mass.
Gas giant TOI-1420 b has 11.9 times Earth’s radius. These estimates make its mean density about 67 times lower than Earth’s.
More
A planet can occupy a huge volume with relatively little mass: its gaseous envelope accounts for much of its size. The measured radius does not mark a solid surface.
Each bar is a ratio to Earth: one for volume, one for mass. Earth’s volume and mass are each set to 1. The short mass bar does not mean the planet is small.
- Mass Earth masses
25.1 (2026)
- Radius Earth radii
11.89 (2026)
- Original study
Yoshida et al. (2023), AJ 166, 181
NASA archive snapshot 2026-10-05: radius 11.89 Earth radii, mass 25.1 Earth masses. Spherical volume scales with radius cubed: 11.89³ = 1,681. Earth/planet density ratio = 1,681 / 25.1 = 67.
Both values checked against Yoshida et al. (2023), AJ 166, 181: radius 11.89 ± 0.33 Earth radii, mass 25.1 ± 3.8 Earth masses. Central estimates, not an exact volume or a world record. Reducing radius and increasing mass by one reported uncertainty still gives a density ratio above 50: a sensitivity check, not a confidence interval. Archive parameters can mix papers, so this calculation is not applied automatically to every planet.
A question for this picture
What holds such a diffuse gaseous envelope together?