'Synestia': Fast Facts About the Newly Proposed Type of Planetary Object

Planetary scientists from Harvard University and University of California-Davis have proposed a new type of planetary object that may look like indented disk or a red blood cell.

The proposed planetary object, described in a paper published in the Journal of Geophysical Research-Planets, is called "synestia", taken from the word "syn-" that means together and "Hestia", who is the Greek goddess of architecture and structures. Synestia is a donut-shaped mass of hot, vaporized rock formed through the collision between two rotating objects.

"We looked at the statistics of giant impacts, and we found that they can form a completely new structure," said Sarah Stewart, a professor in the Department of Earth and Planetary Sciences at UC Davis, and one of the scientists proposing synestia as a new type of planetary object, in a press release.

Stewart is joined by Simon Lock, a graduate student at Harvard University. The two planetary scientists want to know what happens when two spinning objects smash with each other. Rotating objects are known to have angular momentum. Upon collision, the angular momentum of both objects should be conserved.

To determine the result of the collision between two large objects with both high energy and high angular momentum, the researchers developed a model that shows the result of a giant impact between two Earth-sized objects smashing with each other.

The researchers observed that giant impact between two objects with high energy and angular momentum could form a new larger structure that may appear to look like an indented disk or a red blood cell. The newly formed structure will consist mostly of vaporized rocks, with no solid or liquid surface.

Stewart and Lock claim that most of the planets were once synestia. They noted that even Earth might actually pass through a synestia phase. However, the synestia phase of Earth would not last very long, about a hundred years or so before itlost enough heat and condense back into a solid object.