Synestia Is a New Type of Planetary Object (image) University of California - Davis Share Print E-Mail Caption Rocky planets are thought to form from giant impacts between planet-size bodies. Impacts with high energy and high angular momentum could form a synestia, a rotating mass of vaporized rock, where outer layers of the vaporized planet are in orbit around the rest of the body. Synestias give new insights into how planets and moons form. This figure shows to scale a rocky planet, a molten disk/ring structure, and a synestia all with the same mass (about one Earth mass). Credit Simon Lock, Harvard University Usage Restrictions May be used with acknowledgement of the source. 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.