The relationship between the Earth and Sun is interwoven and intimate. The high temperature and pressure creates disturbances in the Sun’s corona that produce solar winds. These winds affect the atmosphere not only on Earth, but also other planets throughout the solar system as well. The image above displays solar winds around Venus. Stunning!
What Are Solar Winds?
Solar winds are streams of high-speed particles that are ejected from the upper atmosphere of the Sun. They consist mainly of protons and electrons that blow out in every direction from the Sun’s corona.
What Causes Solar Winds?
Scientists are still studying the cause of these solar ejections. They appear to occur in relationship to loss of mass in the Sun’s surface. The particles are flung outward from the corona in a thin, plasma stream. When these charged particles reach the terminal velocity of 400 kilometers per second, they begin to feed the solar wind. The particles escape the Sun’s gravity through kinetic energy and the extremely high temperatures of the corona.
Components of Solar Wind
Solar wind generally comes in two types: slow solar wind and fast solar wind. Slow solar winds are thought to originate near the Sun’s equator. These winds are associated with closed solar field lines that cause them to move slower. Fast solar winds extend eject from coronal holes through open magnetic field lines. The lines do not impede the speed of the charged particles, and therefore they move faster.
Solar Winds and CMEs
Coronal mass ejections, often called CMEs, are bubbles of charged gas that erupt from the Sun’s corona. They occur when magnetic field lines twist to form solar flares and become so warped that they stretch like rubber bands. These flares will eventually snap, break and reconnect at other points. The gaps that form when this happens can no longer hold the Sun’s plasma on its surface and it explodes into space. The constant stream of charged particles that are the solar wind then carries this hot plasma cloud to the Earth’s magnetic sphere. CMEs bring increased radiation to our atmosphere, as well as charged particles of matter that interact with the magnetic field that surrounds the Earth. CMEs generally reach the Earth within 1 to 5 days or eruption.
Effects of Solar Winds
Solar winds cause effects that can be detected on Earth. The increase energy from the winds flows into the magnetosphere that surrounds the Earth, causing magnetospheric substorms in the polar regions. When the solar wind collides with the Earth’s ionosphere, atmospheric particles become excited. They must release this additional energy to return to their normal state. When the energy is released, they cause the aurora, or northern lights, that are seen as bursts of colored, dancing light. The wind also brings increased radiation to the atmosphere, which can damage electronic equipment and can be a hazard to astronauts in space.
Image Credit: ESA (Image by C. Carreau)