HAT-P-11 b stands in the Codex as a true ice giant that transits a bright orange K-type dwarf 123 light-years away. With a radius of 4.4 × Earth and a mass near 25 Earths, it is a Neptune analog Kepler watched for years. It completes an orbit every 4.9 days at 0.053 AU, far too hot for the habitable zone, yet its atmosphere is unusually readable: Hubble found water vapor in a relatively clear envelope, and later work added ammonia with hints of carbon dioxide and methane. This well-lit textbook Neptune stands in the Galactic Codex as proof that ice giants can be studied molecule by molecule, not only as distant blue silhouettes.
