the Proposed Interior Structure of Pluto (image) Hokkaido University Share Print E-Mail Caption The proposed interior structure of Pluto. A thin clathrate (gas) hydrate layer works as a thermal insulator between the subsurface ocean and the ice shell, keeping the ocean from freezing. Credit Kamata S. et al., Pluto's ocean is capped and insulated by gas hydrates. Nature Geosciences, May 20, 2019. Usage Restrictions These figures are copyrighted and can be used for reporting this study without obtaining permission if properly credited. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.