# Moon phases and lunar calendar, october 2021 (Chicago, United States)

The lunar calendar originates from time immemorial, when the study of the moon was reduced to simple visual observation. Today, mathematical models are available that allow us to accurately predict the moon phases, its position and many other parameters. This allows you to make a complete lunar days calendar for a month, for a year and for any period.

When the Moon moves around the Earth, and the Earth around the Sun, the Moon periodically changes the appearance of its illumination, which is called the phase of the moon. Phases are usually divided into quarters: "new moon", "first quarter", “full moon”, “last quarter”. Sometimes the moon phases are divided into 8 parts, adding after each of the main phases such as “waxing crescent”, “waxing gibbous”, “waning gibbous” and “waning crescent”. Our site allows you to find out what is the moon phase today, as well as view the phase calendar by year.

The lunar calendar consists of 29 or 30 lunar days, which are counted during the moon phase, such as the new moon. This method of counting intervals is called the synodic lunar calendar.

Since the lunar days do not coincide with the sunny days, the lunar month is different from the calendar month. By analogy with a calendar day, the lunar day begins and ends with the moon rising, which can occur at any time of the day.

The moon phase calendar has many uses and is useful not only for astronomers and mystics. During the moonrise and moonset, when the moon is close to the horizon, an optical illusion is created, in which it seems that its size is much larger than when the moon is high in the sky. Take note of this if you want to create a romantic moment in the open air. If you are a photographer, then know that the best shot can be taken at the time of the super moon - this is the full moon phase at the moment of being in perigee - the point of minimum distance to the Earth. Which a lunar day today should be known to the gardener, because the gravity of the moon affects all living nature and its biorhythms. Therefore, it is important to know what moonlit day it is better to plant or feed plants. Today is a lunar day: 11, moon phase now: 🌔 Waxing Gibbous.

In the III century BC, the ancient Greek astronomer Aristarchus of Samos proposed the first scientific method for determining the distance to the Sun and Moon, as well as their size. This work not only laid the foundations of trigonometry, but also became the foundation for the subsequent defenition of the scale of the solar system. Centuries later, the progress of astronomy reached predictive accuracy, but the mathematical model of the Earth-Moon-Sun system still improving. Our online calculator has already made all the complicated calculations so that you always know what the moon is now: its altitude above the horizon, azimuth angle, time of moonset and moonrise, percentage of illumination, angular diameter, moon phase, in what zodiac sign and in what constellations at the moment, as well as what are the lunar days. Please note that values such as the time moonrise and moonset depend on the location of the observer, therefore, for the correct results, you must specify the location or coordinates for the calculation.