NASA's Spitzer Infra Red Space Telescope.

Rare Luminous Blue Variable star - G79.29+0.46, located between Deneb and Sadr.

This image is a widefield composite mosaic from the Cygnus X region of the sky between the star Deneb and the diffuse emission nebula region of Sadr, taken by NASA's Spitzer Infra Red Space Telescope. The red circular object near the centre of the image is 79.29+0.46, an extremely rare type of very bright, unstable, volatile star called a Luminous Blue Variable star (LVB). The two red circles are shells of material that were cast off from the outer layers of the star and formed by the outward shock waves of these two recent massive expulsions, each expulsion being not quite at the energy level of a supernova.

This star and the other objects in this image can not be seen with regular optical telescopes that use the normal visible light spectrum, such as the Hubble Space Telescope. That's because this entire field is shrouded in multiple layers of dense, opaque dust and gas clouds. Visible light cannot penetrate these opaque dust and gas structures, but infra red light with its much longer wavelengths can.

Infra red light waves are emitted by the space objects in the form of varying degrees of heat energy—longer wavelengths in the red part of the light spectrum—and the telescope's camera sensors register these different heat energy signals to form images. This is how heat-sensitive cameras today can find people from the air who are lost in the forest.

The above image is composed of 3 separate image exposures taken at three different IR wavelengths, 5.8 μm (microns), 8 μm and 24 μm. We then take these different wavelength images and in our computers we assign different colours to the different wavelengths and combine them to form a colour image like the one seen above. Here I have assigned the colour blue to the 5.8 μm image, green to 8 μm and red to 24 μm.

To learn more about G79.29+0.46, LBV stars, and this particular mosaic image go to NASA's APOD page here: apod.nasa.gov/apod/ap170925.html . Also go here: slate.com/technology/2016/09/judy-schmidt-image-of-the-du... and here: www.spitzer.caltech.edu/images/4868-ssc2012-02a-Stars-Bre... .

Thank you Judy Schmidt:

My thanks to Judy Schmidt, a fellow amateur astronomer and Flickr photo gallery member, whose wonderful astro-images have inspired me to recently discover and explore for myself the Spitzer Space Telescope data archives and to read and learn about IR imaging. You can find Judy's amazing work here: www.flickr.com/photos/geckzilla/

Data acquisition: Spitzer Space Telescope, NASA

Data processing: Rudy Pohl

Image: RGB image as per colour mapping below

Colour mapping:

.... red channel: 24 μm Spitzer

.... green channel: 8 μm Spitzer, + (.5*red Spitzer + .5*blue Spitzer)

.... blue channel: 5.8 μm Spitzer

Processing software: ESA/ESO/NASA Fits Liberator 3, Photoshop CS5

Processing Note:

When the image data from the green channel is combined into the RGB image in the scientifically correct proportion together with the blue and red channels, the resultant image is overwhelmingly green, far too green for my personal tastes from a purely aesthetic perspective. Therefore, I took the liberty to significantly suppress the green in all three of my Cygnus X Spitzer images, this one included.