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Earlier ignition for first stars

The first stars in the Universe lit up later than was previously thought.

That is the conclusion of scientists working on Europe's Planck satellite, which has made the most precise map of the "oldest light" in the cosmos.

Earlier observations of this radiation had suggested that the first generation of stars burst into life about 420 million years after the Big Bang.

The new Planck data now indicates they fired up around 560 million years after the Universe got going.

Prof Richard McMahon from Cambridge University, UK, uses large telescopes to study this period. He discussed the implications of the Planck findings with our science correspondent Jonathan Amos.