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. Click on image for full size version (55K GIF) Image by Dynamics Explorer courtesy of L. Frank

The aurora is also known as the northern and southern lights. From the ground, they can usually be seen where the northern and southern auroral ovals are on the Earth. The northern polar auroral oval usually spans Fairbanks, Alaska, Oslo, Norway, and the Northwest Territories.

During geomagnetic storms, however, more particles impinge upon the atmosphere, and the auroral ovals expand to absorb the excessive energy. The northern polar auroral oval can expand to latitudes of 50 or even 40 degrees. Thus there are times when the aurora can be seen as far south as Michigan, Oregon or even farther south.

Auroral classification is quite complex. In its simplest form, aurora can be broken down into these types: polar auroral (pictured and discussed above), equatorial arcs (pictured in the above image), mid-latitude aurora and the SAR arc.

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 auroral oval. Click on image for full size version (55K GIF) Image provided by Dynamics Explorer courtesy of L. Frank

The aurora is also known as the northern and southern lights. From the ground, they can usually be seen where the northern and southern auroral ovals are on the Earth. The northern polar auroral oval usually spans Fairbanks, Alaska, Oslo, Norway, and the Northwest Territories. Sometimes, when the Sun is active, the northern auroral oval expands and the aurora can be seen much farther south.

The image to the left shows the northern oval where the aurora lights up the atmosphere, and the aurora which is found at the equator, called the equatorial arcs.

This image shows the ring where most of the aurora occur in the northern hemisphere. Click on image for full size version (55K GIF) Image by Dynamics Explorer courtesy of L. Frank

The aurora is also known as the northern and southern lights. They are called northern lights if they are seen in the northern hemisphere and southern lights if they are seen in the southern hemisphere.

The auroral lights often appear towards the poles of the Earth. So in the northern hemisphere, aurora is seen most often around Alaska, Norway, and the Northwest Territories. But sometimes the aurora can be seen as far south as Michigan, New York and Oregon. Have you ever seen the aurora?

The aurora is formed when particles from the Sun enter the Earth's atmosphere. This causes the atmosphere to light up. We see these lights and call them aurora.