Author: Chris Kirkland, Professor of Geochronology, Curtin University

Imagine floating in space, gazing on a frozen white orb. The ball hangs in the void, lonely and gleaming in the light from its star. From pole to equator, the sphere is covered in a thick crust of ice. In orbit around the white planet is a single cratered moon. You are gazing on Earth in the Cryogenian period, 700 million years ago. This is about three times as long ago as the earliest dinosaurs roamed – but still not long in the scheme of Earth’s mind-bending 4.5 billion years of history. During the Cryogenian, our planet was plunged into…