磁顶，又称磁层顶。主要指地球磁场与太阳风作用形成的磁层的边界层。当然也可指一切磁化行星与恒星风作用形成磁层的边界。磁层顶外侧一直到弓形震波处被称磁层鞘。磁层顶内侧是磁层的边界层。

Chapman和Ferraro（1931，1932）首先提出地球磁场边界层的存在。1960年代，探索者10号和12号首先探测了这一区域。

The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet’s magnetic field and the solar wind. The location of the magnetopause is determined by the balance between the pressure of the dynamic planetary magnetic field and the dynamic 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 motion) along the magnetopause move in the direction of the solar wind flow in response to small scale variations in the solar wind pressure and to Kelvin-Helmholtz instability.