<p>Revellers touch a stone and chant in the stone circle as they celebrate the pagan festival of summer solstice at Stonehenge in Wiltshire, southern England, on June 21, 2017. According to pagans, Stonehenge is a sacred place that links Earth, the moon, the sun, and the seasons.</p>

Revellers touch a stone and chant in the stone circle as they celebrate the pagan festival of summer solstice at Stonehenge in Wiltshire, southern England, on June 21, 2017. According to pagans, Stonehenge is a sacred place that links Earth, the moon, the sun, and the seasons.

Photograph by Chris J. Ratcliffe, Getty Images

This Summer Solstice, Earth's Days Are Longer Than Ever

Earth hasn't always had a 24-hour day. Here's what that means for the June solstice.

But Meyers, a geoscientist at the University of Wisconsin, Madison, knows something that gives him a longer view: Over billions of years of Earth’s history, the time it takes Earth to rotate once on its axis has been getting longer.

Meyers and a colleague recently showed that 1.4 billion years ago, a single “day” lasted only about 18 hours. And changes in the gravitational dance between our planet and the moon are causing Earth’s day to get ever so slightly longer each year.

“So if I just wait a few hundred million years,” he says, “I’ll get that extra hour back!”

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