Earth's Days Were Only 19 Hours Long for a Billion Years, Study Finds.
A new study published in Nature Geoscience reveals that Earth's day length stalled at about 19 hours roughly between two to one billion years ago, commonly referred to as the "boring" billion. The timing of the stalling intriguingly lies between the two largest rises in oxygen, suggesting that the evolution of Earth's rotation could have affected the evolving composition of the atmosphere. The study supports the idea that Earth's rise to modern oxygen levels had to wait for longer days for photosynthetic bacteria to generate more oxygen each day.