1 90 0 8000000 X-Ray Images of the North Polar Region Here are X-rays images (shown on the same brightness scale) of the north polar region obtained by Chandra HRC-I on different days, showing large variability in soft (0.1-10.0 keV) X-ray emissions from Earth s aurora. Note that the images are not snap shots, but are approximately 20-min scans of the northern auroral region in the HRC-I field-of-view. The brightness scale in Rayleighs (R) assumes an average effective area of 40 cm2. The day-night terminator at an altitude of 0 km is displayed with lighting. The day-night terminator at an altitude of 100 km is shown by the blue line. Animation (922x461) X-ray emissions from Earth's aurora. 1 0 2004-01-24T20:22:19Z 2004-06-12T07:55:59Z 2004-01-24 20:22:19 1 1 2004-01-24T20:22:19Z 2004-01-30T03:26:49Z http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/frames/923x461/chandra.0001.png -90 90 -180 180 2004-01-30 03:26:50 1 1 2004-01-30T03:26:50Z 2004-02-14T00:17:59Z http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/frames/923x461/chandra.0002.png -90 90 -180 180 2004-02-14 00:18:00 1 1 2004-02-14T00:18:00Z 2004-04-13T04:06:59Z http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/frames/923x461/chandra.0003.png -90 90 -180 180 2004-04-13 04:07:00 1 1 2004-04-13T04:07:00Z 2004-06-12T07:55:59Z http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/frames/923x461/chandra.0004.png -90 90 -180 180 Background Image 0 0 http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/frames/923x461/background-bluemarble-earth.png -90 90 -180 180 Legend 1 3 http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003170/chandra_xray_brightness.png