This stellar whirlpool is a spiral galaxy named NCG 7329, which has been imaged by Hubble’s Huge Discipline Digicam 3 (WFC3). Creating a colourful picture corresponding to this one utilizing a telescope corresponding to Hubble is just not as simple as pointing and clicking a digital camera. Industrial cameras will sometimes attempt to acquire as a lot gentle of all seen wavelengths as they’ll, with a view to create essentially the most vibrant pictures potential. In distinction, uncooked pictures collected by Hubble are at all times monochromatic, as a result of astronomers sometimes need to seize very particular ranges of wavelengths of sunshine at any time, with a view to do the most effective, most correct science potential. With a view to management which wavelengths of sunshine shall be collected, Hubble’s cameras are outfitted with all kinds of filters, which solely permit sure wavelengths of sunshine to achieve the cameras’ CCDs (a CCD is a digital camera’s gentle sensor — telephone cameras even have CCDs!).
How are the colourful Hubble pictures potential provided that the uncooked Hubble pictures are monochromatic? That is achieved by combining a number of completely different observations of the identical object, obtained utilizing completely different filters. This picture, for instance, was processed from Hubble observations made utilizing 4 completely different filters, every of which spans a distinct area of the sunshine spectrum, from the ultraviolet to optical and infrared. Specialised picture processors and artists could make knowledgeable judgments about which optical colours greatest correspond to every filter used. They’ll then colour the photographs taken utilizing that filter accordingly. Lastly, the photographs taken with completely different filters are stacked collectively, and voila! The colorful picture of a distant galaxy is full, with colours as consultant of actuality as potential.