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maltatoday | SUNDAY • 17 JULY 2022 14 EYEWITNESS 4.6 billion years ago NASA'S James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant uni- verse to date. Known as Webb's First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb's view for the first time. This slice of the vast universe cov- ers a patch of sky approximately the size of a grain of sand held at arm's length by someone on the ground. What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-form- ing region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA's James Webb Space Telescope, this image re- veals previously obscured areas of star birth. Called the Cosmic Cliffs, the region is actually the edge of a gigantic, gaseous cavity within NGC 3324, rough- ly 7,600 light-years away. The cavernous area has been carved from the nebula by the intense ultraviolet radi- ation and stellar winds from extremely massive, hot, young stars located in the centre of the bubble, above the area shown in this image. The high-energy radiation from these stars is sculpting the nebula's wall by slowly eroding it away. NIRCam – with its crisp resolution and unparalleled sensitivity – unveils hundreds of previously hidden stars, and even numerous background galaxies. Several promi- nent features in this image are described below. - The "steam" that appears to rise from the celestial "mountains" is actually hot, ionized gas and hot dust streaming away from the nebula due to intense, ultravi- olet radiation. - Dramatic pillars rise above the glowing wall of gas, resisting the blistering ultraviolet radiation from the young stars. - Bubbles and cavities are being blown by the intense radiation and stellar winds of newborn stars. - Protostellar jets and outflows, which appear in gold, shoot from dust-enshrouded, nascent stars. - A "blow-out" erupts at the top-centre of the ridge, spewing gas and dust into the interstellar medium. - An unusual "arch" appears, looking like a bent-over cylinder. This period of very early star formation is difficult to capture because, for an individual star, it lasts only about 50,000 to 100,000 years – but Webb's extreme sensitivity and exquisite spatial resolution have chronicled this rare event. Located roughly 7,600 light-years away, NGC 3324 was first catalogued by James Dunlop in 1826. Visible from the Southern Hemisphere, it is located at the northwest corner of the Carina Nebula (NGC 3372), which resides in the constellation Carina. The Carina Nebula is home to the Keyhole Nebula and the active, unstable super- giant star called Eta Carinae. Webb's First Deep Field This deep field, taken by Webb's Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Tele- scope's deepest fields, which took weeks. The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago. The combined mass of this galaxy cluster acts as a gravitational lens, magnifying much more distant galaxies behind it. Webb's NIRCam has brought those distant galaxies in- to sharp focus – they have tiny, faint structures that have never been seen before, including star clusters and dif- fuse features. Researchers will soon begin to learn more about the galaxies' masses, ages, histories, and composi- tions, as Webb seeks the earliest galaxies in the universe.