The Solar Wind
The Solar Wind
Overview
- The solar wind is a continuous stream of charged particles, made up mainly of electrons, protons and alpha particles with kinetic energy, released from the upper atmosphere of the Sun.
- It was first proposed by the scientist Eugene Parker in the 1950s.
- These particles escape from the Sun’s gravity due to the high kinetic energy they possess.
- The solar wind differs from a solar flare, which is a burst of gas ejected from the sun’s surface, whereas the solar wind is a steady flow of particles.
Effects on Earth
- Interactions between the solar wind and Earth’s magnetic field can create geomagnetic storms, which can cause beautiful auroras (northern and southern lights).
- These interactions can disturb the Earth’s magnetic field causing problems with power grids, satellites and radio communications.
- Prolonged periods of intense solar wind can also damage the atmosphere and contribute to its erosion over time.
Velocity and Composition
- The solar wind does not blow uniformly, but has a variable speed and density.
- There are two types of solar wind: the slow solar wind and the fast solar wind.
- The slow solar wind is denser and slower, with speeds around 400 km/s, and is released from an area around the Sun’s equator.
- The fast solar wind has speeds around 750 km/s and originates from coronal holes close to the Sun’s poles.
- The composition of the solar wind across the heliosphere is roughly 90% hydrogen, 8% helium with the rest being trace amounts of heavier elements such as carbon and iron.
Detection and Study
- Initially the solar wind was detected by observing the effects of solar energetic particles on cosmic rays.
- The solar wind has been studied in more detail by spacecrafts like Ulysses, Voyager, and Parker Solar Probe.
- Understanding the solar wind helps us to understand more about our Sun and the wider heliosphere.