Powerful jets spew out of black hole - Video

Some 2 million years ago, around the time our ancestors were learning to walk upright, a light appeared in the night sky, rivalling the moon for brightness and size but it was more fuzzball than orb.

The glow came from the supermassive black hole at our galaxy's heart suddenly exploding into life.

This novel picture emerges from work announced this week at a conference in Sydney, Australia, which ingeniously pieces together two seemingly unrelated, outstanding galactic puzzles.

As well as offering a welcome way to solve both, it gives us an unexpected glimpse of how the cosmos might have appeared to Earthlings 2 million years ago (see "Which species saw the flare?").

Joss Bland-Hawthorn

"That is when we had Homo erectus running around Earth," says Joss Bland-Hawthorn of the University of Sydney, who led the team behind the work.

It also paints supermassive black holes as unpredictable, and capable of generating some of the brightest flares in the universe, almost on a whim.

That in turn throws up the possibility of modern humans being treated to a similar sight sometime in the future – thankfully we are too far away for a flare-up to pose a risk.