At the terminal shock wave, the particles in the solar wind interact with the interstellar medium, and the speed decreases rapidly from 70-15 million miles per hour to Subsonic speed Below, compression occurs, temperature rises, magnetic field Changes have also taken place. The position of the terminal shock wave is about 75-90 away from the sun Astronomical unit , and with solar flare And so on. The shock wave occurs because the particle velocity in the solar wind decreases from 400 km/s to about 0.33 km/s (the speed of sound in the air) (the impact of density on the actual speed cannot be ignored). Although the density of the interstellar medium is very low, it will still produce a fixed pressure on the solar wind, and the pressure from the solar wind will gradually decrease by the reciprocal of the square of the distance from the sun. When the solar wind is far enough away from the sun, the pressure of the interstellar medium becomes enough to reduce the speed of the solar wind below the speed of sound, which forms a shock wave.
There is evidence that, Voyager 1 The detector flew 94 astronomical units from the sun in December 2004, and the instrument readings on the detector changed, indicating that it had passed through the terminal shock wave of the sun. And combine Voyager 2 The data of [1] 。 stay Star Border Expedition (IBEX) will try to collect more terminal shock data about the solar system. [2] 
