Why are the Images in Black and White?

The cameras on Hubble are equipped with a wide variety of filters that allow astronomers to investigate celestial objects as they appear over a broad range of the electromagnetic spectrum from the ultraviolet to the infrared. Images are obtained one filter at a time and each individual image can be represented in a variety of ways. The simplest way is to represent the intensity at each point in the image on a grey scale, i.e. a black and white image. To make full color images requires obtaining multiple exposures of an object through three or more different color filters. Many objects in the HST archive, however, have been imaged well in only one filter. The black and white gallery gives us the chance to share more of these images with the public.

Image quality is the critical factor that will guide us in selecting images for the black and white gallery. We will include images that have sufficiently long exposures to minimize noise and that cover a range of astronomical objects. We are also interested in images that have aesthetic appeal, an admittedly subjective quality that is difficult to define. We hope you will agree, however, that these new additions to the Hubble Heritage site open a new and exciting way for us to extend our vision through Hubble.