The Phases Of The Moon

For the month characterized by the mode of change in the visible part of the moon during its passage along the orbit around the Earth. These different stages are called phases. Within a month the light of the stars falls on the surface of the moon at different angles. When the Sun lights a Month back, it's actually not visible from Earth, this phase is called the new month (the new moon). A half - cycle of the observed full month (or full moon) as seen from the Earth a portion of its surface facing the Sun. The basis of the Roman calendar was based on lunar month the time during which the Moon goes through a complete cycle of changes.
The length of a day is determined by Earth's rotation around its axis, and it seems to us that the Sun rises and sets. The difficulty in compiling the calendar is that the year is not a whole number of days, but about 365.25 days. 45 G. B. E. Julius Caesar solved this problem and introduced a calendar in which after three years of 365 days each was a 366-day leap year.