protoneptune

Example:The hypothesis of protoneptune was proposed to account for the apparent gap between the orbits of Mars and Jupiter before the discovery of the asteroid belt.

Definition:The proposed explanation for a phenomenon or observation, based on limited evidence as a starting point for further investigation.

Example:Protoneptune, if it existed, would have been considered a planet.

Definition:A celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighboring region of planetesimals.

Example:Before the discovery of the asteroid belt, many astronomers proposed that a protoneptune might have been ejected from the solar system.

Definition:A gravitationally bound system consisting of the Sun and the objects that orbit it, either directly or indirectly.