EXPLORE WINTER 2023 | 21 Designed to look deeper into space than ever before, Webb is equipped with a 21.3-foot primary mirror (2.7 times larger in diameter than Hubble’s) that consists of 18 thin, gold-coated beryllium mirror segments. A larger mirror means greater light-gathering power. But the biggest structure of the observatory is actually its sunshade—clocking in at the size of a tennis court. Webb’s specific orbit around the Sun was chosen to keep it in line with the Earth, allowing the extra-large sunshield to protect the telescope from the light and heat of the Sun, Earth, and Moon. “Hubble completely revolutionized the field of astronomy—and we’re expecting big things from Webb, too,” says Anderson. “But NASA likes to refer to the telescope as a successor to Hubble, not a replacement. That’s mainly because Webb will be studying the Universe in a different light.” The impressive instruments aboard the Webb observatory are working primarily in the infrared range of the electromagnetic spectrum— another upgrade from the technology aboard Hubble. Considered a “next generation” telescope that will utilize unprecedented infrared sensitivity and coverage, it will allow astronomers to begin comparing the faintest, earliest galaxies to today’s spiral and elliptical galaxies—helping add yet another piece to the galaxy-formation puzzle. “Most galaxies seem to be moving away from us. And the farther away a galaxy, the faster it appears to be moving—evidence that we’re living in an expanding universe,” says Anderson. “Over long periods of time, this constant stretching of space alters the light that we can detect from extremely distant objects.” According to Anderson, “redshift” is an electromagnetic example of a familiar physical phenomenon known as the Doppler effect. As an ambulance siren moves away from you, the sound waves become stretched, creating lower-pitched sounds. Similarly, as galaxies are carried away from us, the light that is emitted is stretched out and shifted to longer, redder wavelengths. As a result, redshift increases with distance. The farther away we can observe astronomical anomalies, the further back in time we’re studying. Therefore, in order for scientists to study the origins of the Universe—the earliest star and galaxy formation—Webb’s technology was optimized to detect and document infrared light. Webb can also see beyond the dust clouds that typically hinder visible-light observatories like Hubble. Star formation occurs in dense, dusty clouds that obscure visible wavelengths—but infrared light, with much longer wavelengths, is not blocked. “Star-forming regions are a lot like dusty cocoons, hiding the places where new stars are being born,” says Anderson. “Infrared telescopes like Webb are capable of peering deep within these structures to reveal the earliest stages of star and planet formation.” The Museum’s astronomy team has been busy dissecting Webb’s first images in local media interviews and Current Science presentations. Last July, Anderson was featured on Channel 3 to discuss the Webb images known as First Deep Field and Stephan’s Quintet—the former being the deepest and sharpest image to date of the distant Universe. Webb’s First Deep Field photo, which contains the galaxy cluster SMACS 0723, is teeming with thousands of galaxies—including the faintest objects ever observed in the infrared spectrum. This deep field, taken by Webb’s Near- Infrared Camera (NIRCam), is a composite made from images at different wavelengths. Mind- numbingly, it includes several galaxies seen when the Universe was less than a billion years old— a look back in time to more than 13 billion years ago. Anderson reminds us that this image still represents just a tiny sliver of the vastness of space, and likens the size of the patch of sky to that of a grain of sand held at arm’s length. “It’s amazing to think that we’ll be viewing the Universe when it was just a few percent of its current age—a time when the very first galaxies were starting to take shape.” —Nick Anderson, Senior Astronomer &Manager of Astronomy Photo credit: NASA, ESA, CSA, STScI James Webb Space Telescope construction
RkJQdWJsaXNoZXIy NTczNTM=