In contrast, a calendar year is an integral number of whole days, where a day is the time it takes the earth to rotate once on its axis.
(a calendar year; is; an integral number of whole days, where a day is the time) (a day; is; the time it takes the earth to rotate once on its axis)
a calendar year a day
is is
an integral number of whole days, where a day is the time
the time it takes the earth to rotate once on its axis