NASA’s James Webb Space Telescope has revealed the most distant galaxies ever discovered, some of which date back to just 300 million years after the creation of the universe in the Big Bang — a time when the cosmos was just two percent of its current age.
The primordial galaxies were found by an international team of scientists who were responsible for designing two of the JWST’s cutting edge instruments. The first instrument, known as the Near Infrared Camera (NIRCam), was tasked with observing a tiny patch of the night sky in the constellation Fornax.
Over the course of 10 days, NIRCam observed the light cast out of a population of almost 100,000 galaxies over a range of nine infrared wavelengths. From this dataset, the astronomers isolated 250 of the faintest and reddest galaxies, and targeted them with another of the JWST’s instruments — the Near Infrared Spectrograph (NIRSpec).
Incredible James Webb Space Telescope Images
NIRSpec is designed to collect the light emitted by heavenly bodies, and break it down into its constituent colors. This process creates rainbow-like graphs called spectra. Astronomers can analyze a galaxy’s spectra to discover everything from its elemental composition, to the number of stars existing within it, and even its distance from Earth.
The latter is done by measuring a phenomenon known as redshift. It can take billions of years for the light emitted by very distant galaxies to reach our planet. During this time, the wavelengths of that light stretch and become longer, slowly moving into the ‘redder’ part of the light spectrum.
As light travels Earthwards from its source, it will inevitably pass through vast clouds of interstellar dust and gas. These clouds are known to be good at absorbing certain wavelengths of light, while allowing others to pass through relatively unhindered. This interference creates a distinct pattern in the rainbow spectra.
Scientists were able to figure out the age and remoteness of the distant galaxies by observing how much the patterns in the spectra had shifted from their expected positions as a result of redshift.
Using this technique, the scientists discovered four phenomenally ancient galaxies lurking within the JWST data, which are thought to have formed just 300 million years after the creation of the universe in the Big Bang. That makes them 100 million years younger than the oldest galaxy discovered by the Hubble Space Telescope.
This means that the light detected by the JWST left its source roughly 13.4 billion years ago, at a time when the universe was just 2% of its current age. The record breaking age of the galaxies will make them invaluable to scientists attempting to unlock the evolutionary secrets of the early cosmos.
“It is hard to understand galaxies without understanding the initial periods of their development,” explained astronomer Sandro Tacchella from the University of Cambridge who co-authored a study describing the results (via the University of Arizona). “Much as with humans, so much of what happens later depends on the impact of these early generations of stars.”
“So many questions about galaxies have been waiting for the transformative opportunity of Webb, and we’re thrilled to be able to play a part in revealing this story.”
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Image Credit: Northrop Grumman.
Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years of experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer