Gregorian Calendar: Year 2001

Gregorian Calendar = This Month | Gregorian Calendar = This Year
Gregorian Calendar <= Previous Month | Gregorian Calendar => Next Month
Gregorian Calendar <= Previous Year | Gregorian Calendar => Next Year
Gregorian Calendar <= Previous Year Whole | Gregorian Calendar => Next Year Whole

The Gregorian Calendar is a pure Solar Calendar, based only on the the dual movement of the Sun and the Earth. A solar year has 365 days or 366 for a bissextile year, ignoring the month (the Moon). While a Solilunar calendar, integrating the triple motion of Sun-Earth-Moon, just as the Chinese Calendar, takes the motion of the Moon in consideration, describes precisely the Month of about 29 days, a whole revolution around the Earth.