This stellar whirlpool is a spiral galaxy named NCG 7329, which has been imaged by Hubble’s Vast Discipline Digital camera 3 (WFC3). Creating a colourful picture akin to this one utilizing a telescope akin to Hubble will not be as easy as pointing and clicking a digicam. Industrial cameras will sometimes attempt to accumulate as a lot gentle of all seen wavelengths as they’ll, with a view to create essentially the most vibrant photos potential. In distinction, uncooked photos collected by Hubble are all the time monochromatic, as a result of astronomers sometimes wish to seize very particular ranges of wavelengths of sunshine at any time, with a view to do one of the best, most correct science potential. In an effort to management which wavelengths of sunshine will probably be collected, Hubble’s cameras are geared up with all kinds of filters, which solely enable sure wavelengths of sunshine to succeed in the cameras’ CCDs (a CCD is a digicam’s gentle sensor — telephone cameras even have CCDs!).
How are the colourful Hubble photos potential on condition that the uncooked Hubble photos are monochromatic? That is achieved by combining a number of totally different observations of the identical object, obtained utilizing totally different filters. This picture, for instance, was processed from Hubble observations made utilizing 4 totally 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 finest correspond to every filter used. They’ll then shade the pictures taken utilizing that filter accordingly. Lastly, the pictures taken with totally different filters are stacked collectively, and voila! The colorful picture of a distant galaxy is full, with colours as consultant of actuality as potential.