Magnetopause
The magnetopause is the border between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the border between the planet's magnetic field and the solar wind. The location of the magnetopause is figured out by the balance between the pressure of the dynamic planetary magnetic field and the energetic pressure of the solar wind. As the solar wind pressure increases and decreases, the magnetopause moves inward and outward in response. Waves (ripples and flapping movement) along the magnetopause move in the direction of the solar wind flow in response to small-scale different versions in the solar wind pressure and to Kelvin-Helmholtz instability.