Answer:
Encounter Hypothesis
Explanation:
The encounter hypothesis is one of the oldest theories that contributed to the understanding of the solar system and the planets.
This hypothesis says that a collision took place as a result of which a large amount of gas was released from the sun which was migrating more towards the same directions around the sun.
The sun eventually passed through a large, dense and thick interstellar cloud and it later appeared in the form of a gaseous envelope. This later gave rise to the creation of planets and finally formed the solar system. This entire formation of planets and the solar system took a huge amount of time.
This can be considered as an alternative to the nebular theory.
