Solar wind
The solar wind is the continuous outflow of plasma from the Sun's outer atmosphere, the corona. Composed chiefly of protons and electrons and carrying the Sun's magnetic field, it varies in speed and density; fast streams are commonly associated with coronal holes. The wind fills the heliosphere and interacts with planets and their magnetic environments. At Earth, these interactions help produce auroras and can contribute to geomagnetic storms that affect technology.
Nature and origin
The solar wind is a persistent flow of charged particles that expands outward from the Sun's corona, the hot outer part of its atmosphere. It is a plasma made mainly of protons and electrons, with helium nuclei and trace amounts of heavier ions. Because the particles are electrically charged, the outflow also carries the Sun's magnetic field into interplanetary space. The field is twisted into a spiral by the Sun's rotation, forming the interplanetary magnetic field.
Fast and slow streams
The wind is not uniform. NOAA describes the slow wind near the Sun's equatorial plane as typically moving at about 400 kilometres per second, while high-speed streams from coronal holes commonly reach about 500–800 kilometres per second. As the Sun rotates, fast and slow flows meet and form changing structures in the heliosphere. The origin and acceleration of the slower component are less fully understood than those of the fast wind and remain active subjects of solar research.
The heliosphere
As the outward flow travels past the planets, it creates a vast region dominated by solar material and magnetic fields called the heliosphere. The heliosphere extends far beyond the planetary orbits and is bounded by the heliopause, where the outward pressure of the solar wind is balanced by the surrounding interstellar medium. Its size and shape change as the Sun's activity and the strength of the wind vary. The heliosphere also moderates the amount of galactic cosmic radiation that reaches the planetary region, while each planet's own magnetic field and atmosphere provide additional, different kinds of shielding.
Interactions and space weather
At Earth, the magnetosphere deflects most of the solar wind, but some particles and energy enter near the polar regions and contribute to auroras. Changes in wind speed, density, and magnetic-field direction can disturb Earth's magnetic environment. High-speed streams and other solar eruptions can drive geomagnetic storms, which may disrupt satellites, radio and navigation signals, and power systems. A coronal mass ejection is a distinct, large eruption of solar plasma and magnetic field; it can interact with the ambient solar wind, but the two terms do not mean the same thing.
Discovery and observation
Evidence for a continuous solar outflow accumulated before it had a name. In 1958, physicist Eugene Parker published a theory explaining how hot coronal gas could expand into space, building on earlier clues such as the behaviour of comet tails. The Soviet spacecraft Luna 1 detected solar-wind particles in 1959, and NASA's Mariner 2 confirmed the observations in 1962. Modern missions, including NASA's Parker Solar Probe, measure particles and magnetic fields much closer to the Sun, helping scientists investigate how the wind begins and accelerates.
Key facts
- Source
- The Sun's corona, its hot outer atmosphere.
- Composition
- A plasma consisting mainly of protons and electrons, with helium nuclei and trace heavier ions.
- Typical speeds
- NOAA describes slow equatorial wind at about 400 km/s and fast coronal-hole streams at about 500–800 km/s.
- Magnetic field
- The solar wind carries the Sun's magnetic field outward, where solar rotation twists it into a spiral.
- Outer boundary
- The heliopause marks the boundary of the heliosphere, where solar-wind pressure meets that of the interstellar medium.
Timeline
1958
Eugene Parker published a theoretical model of the outward flow of gas from the solar corona.
1959
Luna 1 detected particles from the solar wind.
1962
Mariner 2 confirmed solar-wind observations during its interplanetary mission.
2021
NASA announced that Parker Solar Probe had entered the corona and sampled particles and magnetic fields there.
Ask about this article
Answers use only “Solar wind” and its references, with citations.
References
- 1.What Is the Solar Wind?
NASA Science · other · reliability: high · retrieved 18 October 2026
Supports: Overview of the solar wind's origin, charged-particle composition, magnetic field, planetary interactions, and heliopause.
- 2.Heliosphere
NASA Science · other · reliability: high · retrieved 18 October 2026
Supports: Defines the heliosphere and heliopause and describes the solar wind's role in shaping the space environment and shielding planets from much galactic cosmic radiation.
- 3.Solar Wind
NOAA / National Weather Service Space Weather Prediction Center · other · reliability: high · retrieved 18 October 2026
Supports: Describes solar-wind composition, fast and slow streams, coronal-hole sources, representative speeds, and effects on geomagnetic activity.
- 4.The solar wind
European Space Agency · other · reliability: high · retrieved 18 October 2026
Supports: Explains the solar wind's charged particles, carried magnetic field, heliosphere, interaction with Earth's magnetosphere, and space-weather effects.
- 5.Parker Solar Probe and the Birth of the Solar Wind
NASA, Goddard Space Flight Center · other · reliability: high · retrieved 18 October 2026
Supports: Historical account of Parker's 1958 theory, Luna 1's 1959 detection, Mariner 2's 1962 confirmation, and research on solar-wind streams.
- 6.Parker Solar Probe
NASA Science · other · reliability: high · retrieved 18 October 2026
Supports: Mission details and explanation of Parker Solar Probe's measurements of solar-wind particles and magnetic fields in the Sun's corona.
- 7.Dynamics of the Interplanetary Gas and Magnetic Fields
E. N. Parker, The Astrophysical Journal, vol. 128 (1958), pp. 664–676; American Astronomical Society, copy hosted by Catholic University of America · other · reliability: high · retrieved 18 October 2026
Supports: Original peer-reviewed paper presenting Parker's theoretical treatment of outward flow from the solar corona and its magnetic-field consequences.
References are suggested by the research engine and may be incomplete. Unverified URLs are omitted rather than guessed.
Article history
- Version 118 October 2026 · EditorCreated by Zapia