Assertion: leap year's day | /r/CapableOf | exist to keep the calendar year
Facets:
value: in synchrony with the astronomical year
type: OTHER
Source sentences:
text: This extra day, which falls on February 29 and is called Leap Day or Leap Year Day, exists to keep the calendar year in synchrony with the astronomical year, or the time it takes Earth to make a full rotation around the sun.