Interpreting Auroral Activity from Space

These images are derived from the very sensitive camera's on the polar orbiting NOAA-21, NOAA-20 and NOAA Suomi spacecraft. Spacecraft data is processed in near real-time by Solar Terrestrial Dispatch and presented here for public consumption.

The spacecraft are aligned in a train over the polar regions and are separated by about 25 minutes from each other. It takes ~90 minutes to complete one pass around the Earth.

Only night-time data is selected for these images. Daylight data is discarded. The brightest pixels within the most recent satellite passes are displayed. NOAA-21 data overwrites prior data. Suomi and NOAA-20 data are merged with NOAA-21 data with the brightest pixels selected.

During the polar summerm the sun never sets over the polar region. Daylit data is excluded, which is why there is a black hole over the poles. During this time, rayleigh scattering of light dominates the data except in areas where the sun has set and auroral activity is strong enough to be seen at lower latitudes (near southern Australia, for example).

The 24-hour peak auroral activity images use 24-hours of peak night-time emissions. As such, they are naturally noisier than the "recent" auroral activity maps that use only a portion of the last 24 hours of data, but they show (and hold) the peak emissions observed during the night around the polar region.

The yellow dotted line represents the center of the last swath of data from the indicated satellite at the time of the latest data (after the "->").