What would it be like to sit out in space and look down on the Earth with special UV glasses? Well, if you can't do that, what if you could send up a camera that could take UV pictures and send them back to us? NASA's Ultraviolet Imager is just the camera that can do that. It was launched in February 1996. This is the most recent picture made with the Ultraviolet Imager. It is updated about every 7 minutes when the Polar spacecraft is in contact with the Earth. Its main job is to make pictures in the UV of the aurora, or sometimes called the northern and southern lights. Because of special filters, the glare of the bright Sun is not a problem and the aurora can be seen both on the night and day side of the Earth.

What do the colors mean? When the activity of the aurora is low, we don't see much and the color of the images tend to be white/light blue/green. When the activity of the aurora is high, the images are yellow/red in the regions of intense aurora. During large magnetic storms, these images will show the aurora to be red/dark red and change form from one image to the other. The aurora is a result of energy being deposited in the Earth's atmosphere about 100-150 km up in the form of energetic electrons and protons. These electrons collide with the Earth's atmosphere, which excite its constituents (primarily molecular nitrogen and atomic oxygen). The excited molecules or atoms release the energy in the form of light. The UVI detects the ultraviolet light that is released. The time is the Universal Time (same as the time in London, England). Subtract 6 hours to get US Central Standard Time or 5 to get US Central Daylight Saving Time.