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

Easter's date is based on the lunar calendar. Easter is observed on the first Sunday after the first full moon following the spring equinox. Easter can be as early as March 22 or as late as April 25.

After last week’s letter, I received an email from someone who might or might not be related to me (for lo, these many decades) and who explained in detail what ...

Every year between March 19 and 21, the Northern Hemisphere experiences a celestial event that has captivated humans for millennia: the Spring Equinox. This moment, when day and night are nearly equal ...