This is a star in its quiet death throes (HST). The image was produced using narrow band filters in visible light. Different narrow filters can be used one at a time to reveal the presence of certain elements such as N (blue), oxygen (green) and hydrogen (red). When narrow filter images are added together, you don't see true color (how they would really look if you were there) because the narrow filters have eliminated light at other visible wavelengths. But this kind of image shows us the distribution of these elements of a given electronic excitation. This information helps us understand how stars die and return the elements they made in their youth back into outer space, to seed the next generation of star formation.

Sometimes, comparing images of different wavelengths gives us some real surprises, like for the galaxy on the following page.