Happy Lunar New Year! According to the Chinese lunisolar calendar, the new year began Saturday. For many, like our host Regina G. Barber, this... The science and shared history behind the Gregorian ...

In honor of Leap Day, this read is for the history nerds. Ever wonder how America caught our calendar up with the rest of the world? In September 1752, we skipped 11 days. According to NASA, the Earth ...

We're in a leap year, and Friday — Feb. 29 — is Leap Day. Our calendar is based on 24-hour days, but the orbital period of the Earth (our year) is not an exact multiple of days. The Earth's orbital ...

You can track the start of spring and the phases of the moon—or you can turn to a formula by mathematician Carl Friedrich ...