Assertion: calendar's year | /r/HasProperty | based on two solstices
Facets:
value: a number of years apart
type: TEMPORAL
value: to average out periodic variations
type: PURPOSE
Source sentences:
text: From the time of Hipparchus and Ptolemy, the year was based on two equinoxes (or two solstices) a number of years apart, to average out both observational errors and periodic variations (caused by the gravitational pull of the planets, and the small effect of nutation on the equinox).