A black hole from the dawn of light

Some history: After a rapid phase of expansion immediately after the Big Bang, the plasma of electrons and protons in the universe began to cool about 400,000 years later and the particles clumped together to form neutral hydrogen gas. There was no light in the universe then until gravity formed matter into the first stars and galaxies. Their birth released ultraviolet light that pushed electrons out of the neutral hydrogen gas, putting it in the form we still see the gas in today — and the universe in a new phase where it was transparent to light.

What they saw: Using NASA's Wide-field Infrared Survey Explorer (WISE) and ground-based telescopes in Chile and New Mexico, they detected light from a quasar, bright disks of gas and dust that form as black holes draw in matter. The spectrum of light emitted indicated neutral hydrogen surrounds it — placing it in one of the universe'se key transitions.

"We have an estimate now, with about 1 to 2 percent accuracy, for the moment at which starlight first illuminated the universe," MIT's Rob Simcoe, an author of the study, told NPR.

It's size, given the universe was just 5% of its current age, is also confounding. “This black hole grew far larger than we expected in only 690 million years after the Big Bang, which challenges our theories about how black holes form," study co-author Daniel Stern of NASA's Jet Propulsion Laboratory said in a press release.