Parker spiral

The Parker spiral describes the geometry of the magnetic field as it is carried outward by the solar wind and wound into a spiral by the Sun's rotation. First described by Eugene Parker in 1958, it is the fundamental topology of the heliospheric magnetic field: at the orbit of Earth, the field makes an angle of approximately 45 degrees to the radial direction. The spiral is a dynamical structure that modulates cosmic ray propagation and organizes the heliospheric current sheet.

The Parker spiral is not merely a geometric curiosity; it is the organizational blueprint of the entire heliosphere, a spiral notebook in which the Sun records its rotation for the galaxy to read.