The planet's speedier spin appears to have been due to a slowdown in an ocean current that whips around Antarctica.

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"The Earth speeding up is just like a [twirling ice] skater pulling in her arms," he explained. When the skater does this, she spins faster, because the laws of physics dictate that her body must conserve what's called angular momentum.

"When [the skater] sticks out her arms, they move pretty fast, because there's a big circle. When she pulls in her arms, the circle is smaller, so in order to have the same angular momentum, she has to speed up," Marcus said.

"It is the same with the Earth," in the sense that if an ocean