British Dictionary definitions for protoplanet Expand. protoplanet / ˌprəʊtəʊˈplænɪt / noun. 1. a planet in its early stages of evolution by the process of. one based on the nebula hypothesis. Formation and Examples of Protoplanets. The Protoplanet Hypothesis. Nebular hypothesis Planetary migration. which continues for several million years, but after the forming protoplanet reaches about 30 Earth masses (M. The leading theory is something known as the protoplanet hypothesis , which essentially says that very smal. How Are Planets Formed? 29 Jan . How would i describe the protoplanet hypothesis? Add your answer. Source. Submit Cancel. Report Abuse. The Protoplanet Hypothesis The protoplanet hypothesis suggests that about 5 billion years ago a great cloud of gas and dust rotated slowly in space. The giant impact hypothesis proposes that the Moon formed from. In February 2013 astronomers made the first direct observation of a protoplanet forming in a disk. What is the protoplanet hypothesis? SAVE CANCEL. already exists. Would you like to merge this question into it? MERGE CANCEL. already exists as an alternate. Origin of the Solar System. Protoplanet Hypothesis: The current working model for the formation of the Solar System is called the protoplanet hypothesis. According to the protoplanet hypothesis. Nebular Hypothesis; Examples Hypothesis; Protoplanet Theory; Dust Cloud Theory; Study of Earth's Surface and Interior;.