Science & Technology

Webb – The Most Powerful Space Telescope Ever Built – Will Look Back in Time to the Dark Ages of the Universe

Artist’s impression of the NASA/ESA/CSA James Webb Space Telescope. Credit score: ESA, NASA, S. Beckwith (STScI) and the HUDF Staff, Northrop Grumman Aerospace Methods / STScI / ATG medialab

Some have referred to as NASA’s James Webb Space Telescope the “telescope that ate astronomy.” It’s the most powerful space telescope ever constructed and a posh piece of mechanical origami that has pushed the limits of human engineering. On December 22, 2021, after years of delays and billions of {dollars} in price overruns, the telescope is scheduled to launch into orbit and usher in the subsequent period of astronomy.

I’m an astronomer with a specialty in observational cosmology – I’ve been finding out distant galaxies for 30 years. Some of the largest unanswered questions on the universe relate to its early years simply after the Large Bang. When did the first stars and galaxies type? Which got here first, and why? I’m extremely excited that astronomers could quickly uncover the story of how galaxies began as a result of James Webb was constructed particularly to reply these very questions.

The Universe went by way of a interval of time referred to as the Dark Ages earlier than stars or galaxies emitted any mild. Credit score: STScI

Wonderful proof reveals that the universe began with an occasion referred to as the Large Bang 13.8 billion years in the past, which left it in an ultra-hot, ultra-dense state. The universe instantly started increasing after the Large Bang, cooling because it did so. One second after the Large Bang, the universe was 100 trillion miles throughout with a mean temperature of an unbelievable 18 billion F (10 billion C). Round 400,000 years after the Large Bang, the universe was 10 million mild years throughout and the temperature had cooled to 5,500 F (3,000 C). If anybody had been there to see it at this level, the universe would have been glowing boring crimson like a large warmth lamp.

All through this time, house was crammed with a clean soup of excessive power particles, radiation, hydrogen and helium. There was no construction. As the increasing universe grew to become larger and colder, the soup thinned out and all the things light to black. This was the begin of what astronomers name the Dark Ages of the universe.

The soup of the Dark Ages was not perfectly uniform and due to gravity, tiny areas of fuel started to clump collectively and turn out to be extra dense. The clean universe grew to become lumpy and these small clumps of denser fuel have been seeds for the eventual formation of stars, galaxies and all the things else in the universe.

Though there was nothing to see, the Dark Ages have been an vital section in the evolution of the universe.

Gentle from the early universe is in the infrared wavelength – which means longer than crimson mild – when it reaches Earth. Credit score: Inductiveload/NASA

The Dark Ages ended when gravity shaped the first stars and galaxies that finally started to emit the first mild. Though astronomers don’t know when first mild occurred, the greatest guess is that it was several hundred million years after the Large Bang. Astronomers additionally don’t know whether or not stars or galaxies shaped first.

Current theories based mostly on how gravity varieties construction in a universe dominated by darkish matter recommend that small objects – like stars and star clusters – possible shaped first after which later grew into dwarf galaxies after which bigger galaxies like the Milky Manner. These first stars in the universe have been excessive objects in contrast to stars of in the present day. They have been a million times brighter however they lived very brief lives. They burned scorching and vibrant and after they died, they left behind black holes up to 100 occasions the Solar’s mass, which could have acted as the seeds for galaxy formation.

This artist’s illustration represents the scientific capabilities of NASA’s James Webb Space Telescope. Each imaging and spectroscopy will probably be central to the Webb mission. Credit score: NASA, ESA, and A. Feild (STScI)

Astronomers would love to research this fascinating and vital period of the universe, however detecting first mild is extremely difficult. In contrast to large, vibrant galaxies of in the present day, the first objects have been very small and due to the fixed enlargement of the universe, they’re now tens of billions of mild years away from Earth. Additionally, the earliest stars have been surrounded by fuel left over from their formation and this fuel acted like fog that absorbed most of the mild. It took a number of hundred million years for radiation to blast away the fog. This early mild could be very faint by the time it will get to Earth.

However this isn’t the solely problem.

As the universe expands, it constantly stretches the wavelength of mild touring by way of it. That is referred to as redshift as a result of it shifts mild of shorter wavelengths – like blue or white mild – to longer wavelengths like crimson or infrared mild. Although not an ideal analogy, it’s comparable to how when a automotive drives previous you, the pitch of any sounds it’s making drops noticeably.

Related to how a pitch of a sound drops if the supply is shifting away from you, the wavelength of mild stretches due to the enlargement of the universe.

By the time mild emitted by an early star or galaxy 13 billion years in the past reaches any telescope on Earth, it has been stretched by an element of 10 by the enlargement of the universe. It arrives as infrared mild, which means it has a wavelength longer than that of crimson mild. To see first mild, you might have to be searching for infrared mild.

Enter the James Webb Space Telescope.

Telescopes are like time machines. If an object is 10,000 light-years away, which means the mild takes 10,000 years to attain Earth. So the additional out in house astronomers look, the further back in time we are looking.

The James Webb Space Telescope was particularly designed to detect the oldest galaxies in the universe. Credit score: NASA/Desiree Stover

Engineers optimized James Webb for particularly detecting the faint infrared mild of the earliest stars or galaxies. In contrast to the Hubble Space Telescope, James Webb has a 15 times wider field of view on its camera, collects six occasions extra mild and its sensors are tuned to be most delicate to infrared mild.

The technique will probably be to stare deeply at one patch of sky for a long time, accumulating as a lot mild and data from the most distant and oldest galaxies as attainable. With this information, it could be attainable to reply when and the way the Dark Ages ended, however there are various different vital discoveries to be made. For instance, unraveling this story might also help explain the nature of dark matter, the mysterious type of matter that makes up about 80% of the mass of the universe.

James Webb is the most technically tough mission NASA has ever tried. However I believe the scientific questions it could assist reply will probably be value each ounce of effort. I and different astronomers are ready excitedly for the information to begin coming again someday in 2022.

Written by Chris Impey, College Distinguished Professor of Astronomy, College of Arizona.

This text was first printed in The Conversation.The Conversation
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