Telescopes with circular mirrors/lenses don't have such spikes (in lieu of spikes, diffraction from circular rims creates a pattern of concentric rings called Airy discs). The hexagonal rim of the units that make up the telescope's large mirror give rise to the six spikes. The mirror is composed of 18 individual units, each having the shape of a regular hexagon. The six bright spikes are a result of diffraction from the mirror's edges. The six bright and two fainter spikes around the point sources of light in the photo are an artifact created by the physical limitations of the telescope. The colors of the spikes correspond to the colors of the rim edges and color of struts The six diffraction spikes from the rim along with the two horizontal diffraction spikes from the struts, for a total of eight diffraction spikes. Webb's NIRCam brought the distant galaxies into sharp focus, revealing tiny, faint structures that had never been seen before, including star clusters and diffuse features. The combined mass of the galaxy cluster acts as a gravitational lens, magnifying and distorting the images of much more distant galaxies behind it. The redshifts of nearly 200 of these objects have been measured to date, with the highest redshift measured at 8.498. Many of the objects in the image have undergone notable redshift due to the expansion of space over the extreme distance traveled by the light radiating from them. The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago, covering an area of sky with an angular size approximately equal to a grain of sand held at arm's length.
SMACS 0723 is a galaxy cluster visible from Earth's Southern Hemisphere, and has often been examined by Hubble and other telescopes in search of the deep past. Webb's First Deep Field was taken by the telescope's Near-Infrared Camera (NIRCam) and is a composite produced from images at different wavelengths, totalling 12.5 hours of exposure time. At L 2, the gravitational pull of the Sun combines with the gravitational pull of the Earth to produce an orbital period that matches Earth's, and the Earth and Sun remain co-aligned (as seen from that point) as the Earth and the spacecraft orbit the Sun together. Launched in December 2021, the spacecraft has been in a halo orbit around the second Sun–Earth Lagrange point (L 2), about 1.5 million kilometers (900,000 mi) from Earth, since January 2022. The James Webb Space Telescope is a space telescope operated by NASA and designed primarily to conduct infrared astronomy. Captured by the telescope's Near-Infrared Camera (NIRCam), the image was revealed to the public by NASA on 11 July 2022. The image is the highest-resolution image of the early universe ever taken. Thousands of galaxies are visible in the image, some as old as 13 billion years. The deep-field photograph, which covers a tiny area of sky visible from the Southern Hemisphere, is centered on SMACS 0723, a galaxy cluster in the constellation of Volans. Webb's First Deep Field is the first operational image taken by the James Webb Space Telescope.
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