In 2006, NASA launched a pair of satellites named STEREO-A and STEREO-B separated by 2,000,000 miles in order to create three dimensional imagery of the sun. One of the satellites' primary mission is to study coronal ejections and magnetism using the ultraviolet sensors on-board. Recently, however, during February's eclipse, astronomers chose to calibrate the dark-current in the sensors by focusing on the backside of the moon. This is a procedure (sometimes called dark noise reduction) designed to measure the sensor's output on a completely black substance for subtractive imagery. While conducting the calibration, NASA was able to capture a brilliant video of a quarter sized moon passing in front of an ultra-violet hued sun.