The Pillars of Creation

Cosmic graffiti (1)
Each of the WFPC2's four cameras takes two images with each of its four filters for a good reason. Most of the "snowflakes" you see here are cosmic rays—atomic nuclei whizzing about space at close to the speed of light—that struck the CCD at the moment the image was made. Each cosmic ray leaves a streak across the CCD. Like scratches on a photographic negative, these streaks interfere with the scene we want to see, namely, the Eagle Nebula. Fortunately, cosmic rays arrive randomly, so the marks they leave differ from image to image. Click between the two "Cosmic Graffiti" images, which were taken within moments of each other. Notice how the cosmic-ray marks differ in each.

Now we need to clear away all that annoying cosmic "snow."