Question

All images from Hubble are _____, in which its cameras incorporate a variety of filters, each sensitive to specific wavelengths of light.
A. Advanced diffracted
B. Monochromatic grayscale
C. Lucky cam
D. None of the above

Answer 1

We know that Hubble beams down electrical signals and not actual images. These signals are then interpreted and processed into pixel-specific information that build up together to form an image. This image is passed through various filters which are sensitive to specific wavelengths of light and are then superposed to form the distinctively coloured Hubble images that we see. To do so, we require a neutral base image. Using this information, determine the appropriate option.

Complete step-by-step answer:
Let us begin by understanding how Hubble actually “sees”.
Like a digital camera, the Wide Field and Planetary Camera(s) on the Hubble use charge-coupled devices (CCDs) rather than film to record images. CCDs have an array of light sensitive elements called pixels that turn light falling on them into electrical signals. The images that we see are basically interpretations of each of these signals that are then turned into measurements of brightness, wavelength, etc.
The raw image from the Hubble is generally a far cry from its polished final version that we see. The raw image consists of a blizzard of spurious signals from the cosmos that need to be removed. This image is then processed through filters of different wavelengths of light and is finally superposed together into a mosaic to bring about the images that we see are well defined in colour. These filters of light are indicative of the gaseous atoms constituting the observed body, and each gas is associated with emission lines at specific wavelengths. Usually, the colour blue is assigned to the oxygen-filter, green for hydrogen-filter and red for sulphur-filter. Combining all these together results in a fully processed photograph that acts as a visual aid to deciphering the light and electrical signals processed by the Hubble into measurements.
Thus, all images from the Hubble are monochromatically grayscale (composed of only one colour, here grey, with brighter and darker grey areas representing light of more and less intensity accordingly), taken through filters that pass specific wavelengths of light. This process also imparts false colours to infrared and ultraviolet channels rendered as deep red and deep blue respectively, though they are not in the visible region.

So, the correct answer is “Option B”.

Note: Remember that the Hubble images are not “captured” in a conventional sense, since it involves elaborate tasks of processing data, refining the data, eliminating spurious signals, sending all this information through specific light sensitive filters, superposing all these filtered images together which can ultimately detect light through the visible spectrum, as well as the IR and UV regions, which is otherwise invisible to the human eye. Note that the rich hues of colours that we see in Hubble photos are obtained by letting light build up in its CCDs for over long periods of time since most celestial objects emit colours that are too faint for a glancing detection.