Loading…
Loading contentLoading…
Loading contentA proposed class of exoplanet — a hot world with a hydrogen-rich atmosphere over a planet-wide ocean. If they exist, hycean planets would offer a much wider habitable zone than rocky worlds and be easier to study, but the class is hypothetical and its habitability unconfirmed.
Facts on this topic will be cited from these primary and reference sources.
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.