* Gravitational Influence: The Sun's gravity weakens with distance, but it never truly disappears. Technically, the solar system extends as far as the Sun's gravitational influence is dominant over other stars.
* Oort Cloud: The Oort Cloud is a theoretical spherical shell of icy debris, extending roughly 10,000 to 100,000 AU from the Sun. It's believed to be the source of long-period comets.
* Heliosphere: This is a bubble of charged particles (solar wind) blown out by the Sun. It's thought to extend about 123 AU from the Sun, where it encounters the interstellar medium.
* Interstellar Medium: This is the diffuse gas and dust between stars. The solar system "ends" where the interstellar medium dominates over the solar wind.
* Other Stars: The Sun is just one star in a vast galaxy. The influence of other stars, especially nearby ones, starts to become significant at some point.
So, what's the bottom line?
* There's no simple answer.
* The "edge" of the solar system is a gradual transition rather than a sharp boundary.
* Different definitions (Oort Cloud, heliopause) are used depending on the context.
Ultimately, where the solar system "ends" is a matter of perspective and what criteria you use to define the boundary.
