![]() We are going to witness this miraculous experiment with NASA’s James Webb Space Telescope’s ability to see back in time. But the one that can see years ahead, he has a telescope and he can’t make anybody believe that he has it. The views expressed are those of the author and do not necessarily reflect the views of the publisher.“The fellow that can only see a week ahead is always the popular fellow, for he is looking with the crowd. Read the original article.įollow all of the Expert Voices issues and debates - and become part of the discussion - on Facebook and Twitter. This article is republished from The Conversation under a Creative Commons license. I and other astronomers are waiting excitedly for the data to start coming back sometime in 2022. But I think the scientific questions it may help answer will be worth every ounce of effort. James Webb is the most technically difficult mission NASA has ever attempted. For example, unraveling this story may also help explain the nature of dark matter, the mysterious form of matter that makes up about 80% of the mass of the universe. With this data, it may be possible to answer when and how the dark ages ended, but there are many other important discoveries to be made. The strategy will be to stare deeply at one patch of sky for a long time, collecting as much light and information from the most distant and oldest galaxies as possible. Compared to the Hubble Space Telescope, James Webb has a 15 times wider field of view on its camera, collects six times more light and its sensors are tuned to be most sensitive to infrared light. (Image credit: NASA/Desiree Stover, CC BY)Įngineers optimized James Webb for specifically detecting the faint infrared light of the earliest stars or galaxies. The James Webb Space Telescope was specifically designed to detect the oldest galaxies in the universe. Though not a perfect analogy, it is similar to how when a car drives past you, the pitch of any sounds it is making drops noticeably. ![]() This is called redshift because it shifts light of shorter wavelengths – like blue or white light – to longer wavelengths like red or infrared light. This early light is very faint by the time it gets to Earth.Īs the universe expands, it continuously stretches the wavelength of light traveling through it. It took several hundred million years for radiation to blast away the fog. Also, the earliest stars were surrounded by gas left over from their formation and this gas acted like fog that absorbed most of the light. Compared to massive, bright galaxies of today, the first objects were very small and due to the constant expansion of the universe, they’re now tens of billions of light years away from Earth. They burned hot and bright and when they died, they left behind black holes up to a hundred times the sun’s mass, which might have acted as the seeds for galaxy formation.Īstronomers would love to study this fascinating and important era of the universe, but detecting first light is incredibly challenging. They were a million times brighter but they lived very short lives. These first stars in the universe were extreme objects compared to stars of today. Astronomers also don’t know whether stars or galaxies formed first.Ĭurrent theories based on how gravity forms structure in a universe dominated by dark matter suggest that small objects – like stars and star clusters – likely formed first and then later grew into dwarf galaxies and then larger galaxies like the Milky Way. Although astronomers don’t know when first light happened, the best guess is that it was several hundred million years after the Big Bang. The dark ages ended when gravity formed the first stars and galaxies that eventually began to emit the first light. (Image credit: Inductiveload/NASA via Wikimedia Commons, CC BY-SA) Looking for the first light ![]() ![]() ![]() Light from the early universe is in the infrared wavelength – meaning longer than red light – when it reaches Earth. ![]()
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