NASA

Earth is the only planet among the inner planets that has a significant magnetic field. The domain of the magnetic field is called the magnetosphere. The magnetosphere extends about 10 Earth radii in the direction of the Sun where a shock front called the magnetopause is formed by the interacting solar wind (charged particles that stream out from the Sun). In the opposite direction of the Sun, the magnetotail points away from the Sun for over 1000 Earth radii.

Northern and Southern Lights

We see evidence of our magnetic field when charged particles penetrate the magnetosphere and enter the upper atmosphere. When this occurs, the sky glows in colorful curtains of light, a phenomena called the Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights). Most aurorae occur at an altitude between 80 and 160 kilometers (50-100 miles). The light is created when electrons excite and ionize atmospheric gases, principally oxygen and nitrogen. Because the electrons are confined to the magnetic field lines, and these lines enter the Earth at the Magnetic North and South Poles (which are offset slightly from the geographic North and South Poles), the auroral displays typically take place at higher latitudes.

About the visualization: seeing a magnetic storm

In March 2000, the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) was launched. IMAGE uses neutral atom, ultraviolet, and radio imaging to explore three primary scientific objectives, (1) to identify the dominant mechanisms for injecting plasma into the magnetosphere on magnetic storm time scales, (2) to determine the response of the magnetosphere to changes in the solar wind, and (3) to discover how and where magnetospheric plasmas are energized, transported, and lost during magnetic storms. This animation is composed of neutral atom images of a storm cloud (incoming solar particles) in the Earth's magnetosphere. We are looking from the Sun toward Earth. The red colors represent the highest intensity of incoming particles while the blue and violet represent the lowest intensity.

Ellen Cohen