The James Webb Space Telescope has recently captured a remarkable view of the Hubble Ultra Deep Field, a well-known section of the sky, showcasing thousands of distant galaxies. This new image is invaluable for astronomers aiming to understand how galaxies have evolved over billions of years.
By blending data from its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), Webb provides an extraordinarily detailed perspective. The original Ultra Deep Field was constructed from Hubble observations between 2003 and 2004 and highlights over 10,000 galaxies, some from just under a billion years post-Big Bang.
Webb’s latest observations center on the MIRI Deep Imaging Survey (MIDIS) region, utilizing MIRI’s shortest-wavelength filter. With nearly 100 hours of observation time—the longest for Webb in one filter for an extragalactic field—the telescope unveiled over 2,500 sources, including hundreds of extremely red galaxies. Many of these are likely vast galaxies shrouded in cosmic dust or evolved galaxies filled with mature stars from early in the Universe’s timeline.
Colors in the image represent different infrared wavelengths, bringing out distinct features of these galaxies. Longer mid-infrared wavelengths, shown in orange and red, highlight galaxies rich in dust, intense star formation, or active galactic nuclei (AGN). Smaller, greenish-white galaxies appear more distant, with their light shifted into mid-infrared ranges due to redshift. Most other galaxies are brightest in shorter near-infrared wavelengths, depicted in blue and cyan, as they don’t have enhanced mid-infrared features.
Webb’s exploration of the Hubble Ultra Deep Field offers one of the deepest glimpses into the Universe, illuminating the birth and growth of early cosmic structures.
