This left-hand image shows the northern auroral oval (the bright ring on the top of the silhouetted Earth) and the equatorial arcs (the red traces towards the center of the silhouetted Earth). The right image focuses on the northern polar auroral oval. The red glow in both of the images that surrounds the Earth is the alpha radiation emitted by the geocorona. Both images were taken by Dynamics Explorer 1. Also in both images, the Sun is eclipsed by the Earth.
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