“If you don’t get the beginning right, it’s really difficult to figure out what the whole evolution looked like”. “We are trying to build up the story of how the first galaxies ever emerged and how those evolved into galaxies we see today and we live in today,” said Marusa Bradac, an astronomer at the University of California, Davis, in an interview with NPR. To do that deep stargazing, JWST must look at one patch of the universe for a long time in order to collect as much light as possible from the distant objects astronomers seek to view. Thus, JWST can see both farther and fainter objects than Hubble ever could. Stars and planets that are just forming are surrounded by dust, which absorbs visible light however, infrared radiation can penetrate that dust. There are other benefits in collecting infrared radiation besides viewing faraway objects. What’s more, light from the most distant objects is stretched due to the expansion of the universe, becoming infrared wavelengths, which Hubble cannot easily detect.īy comparison, JWST is designed to collect infrared radiation, thanks to its much larger 21-foot diameter mirror. Hubble has been orbiting Earth and giving us both amazing images of the universe and important scientific results for more than 30 years, but its mirror is only 8 feet in diameter, which limits its ability to observe the most distant objects. The Hubble telescope can also look back in time to a certain extent, but not as far as JWST does. When the first stars formed they also began to emit the first light, which JWST was built to detect. Those atoms grouped together in clumps, eventually becoming stars. The particles from the Big Bang grouped together due to gravity and formed the first atoms. As the universe continued to expand and cool, that glow disappeared and the universe became completely dark, the so-called Dark Ages. Around 400,000 years later, the temperature had cooled to 5,500 degrees Fahrenheit and the universe was glowing dull red. One second afterward, the universe consisted of radiation, hydrogen, helium and high energy particles at a temperature of 18 billion degrees Fahrenheit. The Big Bang occurred 13.8 billion years ago. The James Webb Space Telescope (JWST) will take this idea to the extreme, studying objects so distant that the telescope will essentially be looking back 13.5 billion years - close to the start of the universe. For example, the light from our nearest star system, Alpha Centauri, takes four years to reach Earth, so when we look at Alpha Centauri, we see it as it was four years ago. "We'll have to figure out how to use the telescope in different ways and plan for the unexpected.Light from space always reaches us after a delay. "There are going to be things that we aren't prepared for," she said. Most exciting of all, Milam expects the Webb Telescope to discover things we never even thought to look for, as the Hubble has done many times. We're going to be able to study the atmospheres of planets around other stars that we've never had access to." "We're going to see the first stars and galaxies and understand how the evolution of our universe actually started. And I think the science that's going to come out of this is mind-blowing. NASA's Stefanie Milam, one of the telescope's science officers, said, "JWST is going to rewrite the textbooks. If all goes well, then by the summer of 2022, this machine will get down to its work: Science. We took every piece of it and we did the best we absolutely, possibly could." "Confidence is built, to me, out of, 'Did we do everything that we could possibly have done?' I can confidently say we did everything that we needed to do. Pogue asked, "So, at this point, days away from the launch, how confident are you?" "But all of that is because we have to learn on the ground." "Every time we learn something, we had to repeat a series of tests," said Willoughby. All that additional testing and caution helps explain the telescope's 14 years of delays, and its $9.7 billion price tag.
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