Longer Days May Not Be All That Bad

Earth scientists note that early Earth spun faster on its axis, resulting in shorter days for our infant planet. How short? Per one estimate, a day lasted only six hours 4.5 billion years ago! Days grew gradually longer as the Earth’s rotational spin slowed, in part thanks to the Moon exerting a degree of friction.

One new study published in the journal Nature Geoscience suggests these longer days, with longer daylight hours, may have been what kick-started complex life on Earth. Biogeochemist Judith Klatt (Max Planck Institute for Marine Microbiology) suspected there was a connection between lengthening days and the ever-increasing production of life-sustaining oxygen on our planet.

As one way to test her hypothesis, she and colleagues collected living samples of bacterial life from microbial mats in Lake Huron when she was a postdoc at the University of Michigan. In the lab, they divvied up the samples and exposed different samples to different periods of light, simulating shorter and longer days and nights. The results showed much greater oxygen-releasing activity in samples exposed to ever-longer periods of daylight. The study authors, including Klatt, Arjun Chennu (Leibniz Centre for Tropical Marine Research) and Gregory Dick (University of Michigan) suggest this as just one of many potential factors contributing.