Earth in 12 hours (the clock)
Earth in 12 hours (the clock) EARTH IN 12 HOURS (THE CLOCK) Earth in 12 hours places our planet’s long history in perspective: if 4.5 million years of geological and biological development were condensed into 12 hours, for how long would there have been life on the planet? When did the moon form? Has there always been oxygen in the atmosphere, or where does it come from? And exactly how long have