{"id":21214,"date":"2022-12-15T19:00:04","date_gmt":"2022-12-15T18:00:04","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=130765"},"modified":"2022-12-15T19:42:21","modified_gmt":"2022-12-15T18:42:21","slug":"how-is-colour-added-to-the-jwst-images-an-astronomer-explains","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/how-is-colour-added-to-the-jwst-images-an-astronomer-explains\/","title":{"rendered":"How is colour added to the JWST images? An astronomer explains"},"content":{"rendered":"

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By Dr Alastair Gunn\n \t\t<\/p>

Published: Thursday, 15 December 2022 at 12:00 am<\/p>

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This July we were treated to the first spectacular images<\/a> taken with NASA\u2019s James Webb Space Telescope (JWST)<\/a>. But JWST is an infrared (IR) telescope, meaning that it is not seeing what the human eye sees. In fact, JWST is detecting what we feel as \u2018heat\u2019, just like night-vision goggles, and the JWST images are just a representation of its view in optical light<\/a>. So, the colours in the JWST image are not real \u2013 they are not what your eye would see.<\/p>\n

The colours, however, do represent something real \u2014 the variation in brightness with wavelength. Essentially,\u00a0the\u00a0JWST takes up to 29 greyscale images, each through a different filter which only passes IR light of a certain wavelength.<\/p>\n

The separate images are then assigned a colour; the longest wavelength is \u2018red\u2019 and the shortest \u2018blue\u2019, with the others in between. The \u2018colour\u2019 image\u00a0is then formed from combining the separate filter images.<\/p>\n

In effect, the JWST\u2019s images are shifted up the electromagnetic spectrum from a part we can\u2019t see (IR) into the part we can see (optical).<\/p>\n

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Incidentally, this is how the images from the Hubble Space Telescope are formed, but in that case, the filters are all at optical wavelengths and no shift is being performed.<\/p>\n

If the JWST colour images are not real, why make them? It\u2019s easier for scientists to analyse the images using these composite \u2018false-colour\u2019 images, and it\u2019s aesthetically pleasing to \u2018see\u2019 a representation of what JWST has observed.<\/p>\n

Read more:<\/strong><\/p>\n