The oldest stars in the sky aren't so old after all. They actually lit up the Universe more than 100 million years later than scientists previously thought, according to a new study.
Data from the European Space Agency's (ESA) Planck space telescope originally suggested that the light from some of the very first stars and galaxies lit up the Universe 380,000 years after the Big Bang, ending a period known as the "Dark Ages."
However, new measurements - which studied the Cosmic Microwave Background (CMB), or the light left over from the Big Bang - indicate that this great illumination occurred about 550 million years after the Big Bang. This pushes back the age of the first stars about 100 million years later than Planck's previous estimate.
"While these 100 million years may seem negligible compared to the Universe's age of almost 14 billion years, they make a significant difference when it comes to the formation of the first stars," Marco Bersanelli of the University of Milan, a member of the Planck Collaboration, said in a statement.
The new assessment is based on the afterglow from the CMB, which amazingly can be seen even today covering the whole sky at microwave wavelengths. (Scroll to read on...)
When the first stars began to shine, their light interacted with gas in the Universe and caused atoms to turn back into electrons and protons - a phase dubbed the "epoch of reionization." Since the stars and galaxies prompted the beginning of reionization, scientists said that the new measurements suggest when the first stars and galaxies started to form.
The new Planck findings are crucial because previous studies of the CMB polarization had suggested the first stars were born much earlier, placing the beginning of reionization about 450 million years after the Big Bang.
"These are only a few highlights from the scrutiny of Planck's observations of the CMB polarization, which is revealing the sky and the Universe in a brand new way," said Planck project scientist Jan Tauber.
"This is an incredibly rich data set and the harvest of discoveries has just begun."
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