ESA Science & Technology - Features of the heliosphere

The Solar System is immersed in a protective bubble, known as the heliosphere. This is caused by the solar wind, the expanding plasma of charged atoms and electrons emitted by the Sun, which excludes the local interstellar medium from the area encompassing the Sun and the planets.

The termination shock marks the region where the solar wind is quickly decelerated to subsonic speeds.

The heliosphere is bordered by a layer called the heliopause. Here, the pressure from the solar wind balances that of the interstellar medium.

The bow shock marks the region where the interstellar medium slows down as it impacts the heliosphere.