Another gorgeous image from Hubble! This close-up of NGC 7023, or the Iris Nebula, shows an area filled with cosmic dust. Illuminated from above by the nearby star HD 200775, the dust resembles pink cotton candy, accentuated with diamond-like stars. The "cotton candy" is actually made up of tiny particles of solid matter, with sizes from ten to a hundred times smaller than those of the dust grains we find on Earth, and the "diamonds" are both background and foreground stars.
The image was taken previous to Hubble's recent servicing mission, using the Advanced Camera for Surveys. Astronomers also used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument to try to determine which chemical elements are present in the nebula.
NGC 7023 is a reflection nebula, which means it scatters light from the massive nearby star. Reflection nebulae are different from emission nebulae, which are clouds of gas that are hot enough to emit light themselves. Reflection nebulae tend to appear blue because of the way light scatters, but parts of the Iris Nebula appear unusually red-ish or pink.
See more, including a movie pan of the nebula here.