NASA/Scott Kelly/Wikimedia Commons

An average Earth day used to be less than 19 hours long

In timely news, scientists have determined that some 1.4 billion years ago, an Earth day—that is, a full rotation around its axis—took 18 hours and 41 minutes, rather than the familiar 24 hours, The Guardian reports. According to new calculations published in the Proceedings of the National Academy of Sciences, Earth adds an average of .0000135 seconds to the length of its day every year, a trend that is on track to continue for millions of years more. Researchers came to their conclusion about Earth’s deep time while looking in ancient sediment deposits for markers of climate change related to periodic variations in the planet’s orbit .  

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