The solar wind is continuous flow of charged particles discharged by the Sun. Having extremely high temperatures, violent collisions of gases strip them of electrons, acquiring enough speed to escape the gravitational pull of the sun. When this solar wind comes close to the Earth they interact with Earth’s magnetic field. When the solar wind strikes the Earth’s magnetic field it deforms it into a tear-drop shaped cavity called the magnetosphere. Reaching the Earth’s magnetic field the solar wind sets off auroral displays by exciting atmospheric gases resulting in the emission of visible light. In the Northern Hemisphere the spectacular light show is the aurora borealis or northern lights. In the Southern Hemisphere they are called the aurora australis, or southern lights. In a recent at NASA headquarters, solar solar physicists announced that the solar wind is losing power.
Listen to the briefing by clicking on the player button below.
Or read the article at Science@NASA
The Physical Environment Textbook links: The Solar Wind and Auroras