STAR BLAST. When the universe was less than a billion years old, it was little more than a sea of hydrogen and helium. A sudden blast of star formation turned on lights within the darkness.

NASA/ESA/Adolf Schaller

Over the past century, astronomers have deduced several ways to estimate the age of the universe. At the dawn of this century, the universe’s age remained far from certain. 

But the launch of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck spacecraft changed all that. Still, astronomers’ attempts during the previous century to narrow the age estimates makes for a fascinating detective story.

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