Compass and Scale Image for Comet ISON
At the time of the Hubble observation, the comet was 4.15 astronomical units (386 million miles) from the Sun. The comet was 4.24 astronomical units (394 million miles) from Earth.
The image was created from Hubble data from proposal 13198 J.-Y. Li (Planetary Science Institute), P. Lamy (Laboratoire d'Astrophysique de Marseille), H. Weaver (JHU/APL), M. A'Hearn and M. Kelley (University of Maryland), M. Knight (Lowell Observatory), T. Farnham (University of Maryland), and I. Toth (Hungarian Academy of Sciences).
This image was originally black and white and recorded only overall brightness. These brightness values were translated into a range of bluish hues. Such color "maps" can be useful in helping to distinguish subtly varying brightness in an image.