Ecliptic

Cosmic ray

Physics

Astronomy

Astrophysics

Quantum mechanics

Coronal hole

Interplanetary scintillation

Interplanetary spaceflight

Heliosphere

Plasma

Solar wind

Coronal mass ejection

Interplanetary medium

Living Reviews in Solar Physics

This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ∼0.3 -1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed.

Solar wind stream interaction regions throughout the heliosphere