Here's why:
* Gravitational Dominance: The Sun's immense gravity dominates the solar system. Objects within the solar system are primarily influenced by the Sun's gravity and orbit it directly or indirectly (like moons orbiting planets).
* Escape Velocity: For an object to escape the Sun's gravitational pull, it needs to reach a certain velocity known as the escape velocity. Objects within the solar system generally do not have enough speed to escape the Sun's influence.
* Orbital Stability: Objects within the solar system are generally in stable orbits around the Sun, meaning they are not ejected from the system. This stability is due to the Sun's dominant gravitational force.
Exceptions:
* Comets: While comets technically orbit the Sun, their orbits are highly elliptical and can take them very far from the Sun, even beyond the Oort cloud.
* Interlopers: There are occasional objects that enter the solar system from interstellar space. These objects, like 'Oumuamua, are temporary visitors and are not considered part of the solar system.
In summary: The dominant factor is the gravitational influence of the Sun. Objects within the solar system are bound by its gravity, while objects outside the solar system are not.
