Science Alien calendars would probably include leap year

Leap year: The time it takes the Earth to orbit the sun can't be precisely divided into days. Alien planets are likely to have the same difficulty in measuring time accurately.

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AP Photo/NASA/Ames/JPL-Caltech

Today is a leap day, a calendar oddity that helps align our timekeeping with the orbit of the Earth around the sun. But leap day may not be restricted to the Earth — it could occur on planets around other stars as well, as long as there are beings living there to mark the days, scientists say.