Heliopause

The boundary of the solar cavity is the heliopause, about fifty astronomical units from the sun, where the solar wind pressure is down to the tiny pressure between stars in our arm of the galaxy.

Scientists define the beginning of interstellar space as the place where the sun’s constant flow of material and magnetic field stop affecting its surroundings. This place is called the heliopause. It marks the end of a region created by our sun that is called the heliosphere.

The astronomer says scientists are now trying to figure out what’s on the other side of the heliopause, the boundary between our solar system and intergalactic space.