The Universe’s Oldest Stars Likely Lit Up Way Later Than Once Thought

Data gathered by the European Space Agency’s Planck telescope indicates that the universe was dark for about 550 million years after the big bang

Milky Way
ESA/Michael Benson/Kinetikon Pictures/Corbis

According to a new map of the “oldest light” in the universe, after the birth of the cosmos darkness reigned supreme for around 100 million years longer than previously theorized.

Scientists came to this new theory thanks to data collected by the European Space Agency’s Planck telescope, which “was designed to study the ‘cosmic microwave background’ - the faint radiation echo left by the big bang - with unprecedented accuracy,” writes the Guardian.  

One major change in that background was a moment of re-ionization—when, as BBC News reports, “the cooling neutral hydrogen gas that dominated the Universe in the aftermath of the Big Bang was then re-energised by the ignition of the first stars.” Previous data collected by an American satellite, WMAP, in the 2000’s had estimated that the universe’s re-ionization peaked around 400 million years after the big bang. This presented scientists with a problem, since it conflicted with observations of the early cosmos made by the Hubble Telescope.

But the new data gathered by Planck (and recently published) shows that star formation was likely underway by about 550 million years after the big bang. This new theory effectively solves the previous problem and may eventually alter understandings of dark energy, dark matter and other riddles of the known universe. As BBC News reports:

"This difference of 140 million years might not seem that significant in the context of the 13.8-billion-year history of the cosmos, but proportionately it's actually a very big change in our understanding of how certain key events progressed at the earliest epochs," said Prof George Efstathiou, one of the leaders of the Planck Science Collaboration.

However, there’s no telling the exact moment the universe’s very first stars blinked to life, replacing an era of darkness with visible light. Planck has given researchers data to make the most informed estimate yet, but they say further research and analysis is necessary. Information gathered by new observatories, like the James Webb Space Telescope, which NASA plans to launch in 2018, may get scientists even closer to understanding this and other mysteries of the cosmos.

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