Great Barrier Reef heading for the biggest spawning event on the planet

It’s the world’s biggest synchronised sex event that’s OK to teach your kids about.

Every year just after the full moon in late spring or early summer, the corals of the Great Barrier Reef release trillions of eggs and sperm into the water, usually over the course of about three or four nights.

And this year, that’s set to happen this weekend.

While it’s a spectacle most of us will never see first hand, the ABC will be streaming it as it happens on Friday and Sunday nights in a series called Reef Live on ABC TV and iView.

Despite the sheer scale of the event, scientists have only known about it since 1981. Before that, it was thought that corals brooded and released their fertilised embryos year round.

But in the past 40 or so years, they’ve…