The lunar calendar 날짜계산기 is based on the lunar phases. In contrast, the solar calendar is based on the annual cycles of the solar year. The Gregorian calendar evolved from a lunar calendar system. Whether you choose to use a lunar or solar calendar is up to you, but both are important. Here are some examples.
Moon’s orbit is elliptical
In lunar calendars, the Moon’s orbit is elliptically inclined to the ecliptic, meaning that the Moon varies its apparent size and angular speed according to its location in relation to Earth. For example, a full Moon can appear as much as 30% bigger or brighter at one point in its orbit than it actually is. This non-circular orbit causes the Moon’s average inclination to be 5.145 degrees, which makes the Moon appear to be slightly oblique. Consequently, the Moon is above the horizon at the North and South Poles almost two weeks every month and below the horizon for about six months out of the year.
The Moon’s orbital eccentricity is 0.0549 degrees, and it is subject to solar perturbations. Its instantaneous eccentricity fluctuates with its synodic month period, ranging from 0.0266 to 0.0762 degrees. In lunar calendars, this value is superimposed on the Moon’s instantaneous perigee, which is positioned at the start of every anomalistic month.
The orbit of the Moon is elliptical, with a perigee closest to Earth and an apogee far from the Earth. The distance between the two bodies changes significantly throughout the year, but the average distance is only 382,900 kilometers.
Moon’s orbit is near
The Moon’s orbit is near the lunar calendar if the Sun’s path passes perigee on the Moon. Perigee is located at a point near the lunar orbit when the Moon is at its closest to the Earth. The Moon’s orbit is eccentric. The eccentricity increases when the Moon is near perigee. The eccentricity decreases when the Moon is near apogee.
This is called a synodic month. It is the time it takes the Moon to complete an orbit around Earth and return to the same position as the Earth and the Sun. The next type of month is called a sidereal month, and is shorter than the synodic month. The sidereal month is similar to the synodic month, but is related to the stars. The Moon will orbit the Earth in about 47 days.
The Moon’s orbit is non-circular, so its size varies. In some months, a full Moon appears 30% bigger or brighter. The Moon is nearly five hundred thousand miles from Earth, and the inclination of its orbit is about 5.145 degrees. This means that the Moon is above the horizon at the North and South Poles almost two weeks out of every month, and below the horizon at the South Pole for six months of the year.
The Moon orbits the earth every 27.3 days. The sidereal month and synodic month are different, but the lunar calendar is a similar concept. During a lunar eclipse, the Moon is in the shadow of the Earth, so the Earth’s shadow falls on the Moon.
Chinese lunar calendar
The Chinese lunar calendar is a lunisolar calendar that uses the length of the moon’s orbit around Earth to determine the date. Each month in the Chinese calendar has 29 days and the lunar year has 354 days. Every two or three years there is an extra leap month. Because of this, Chinese dates vary from those of the Western calendar.
The Chinese lunar calendar divides each year into two components: the Earthly Branches and Heavenly Stems. Each stem is named according to the seasons and consists of 60 unique pairs. The two parts of each stem form the year. Once each component is completed, the year’s name is given. This system dates back to about 2000 years.
This calendar was created for practical reasons. It fixes the dates of the lunar new year and other holiday events. It was first used in the Zhou dynasty. In the Zhou calendar, the year starts on the new moon before winter solstice, which is why Chinese lunar calendars are called lunisolar calendars.
The Chinese calendar has continued to be used in China today. In ancient times, the calendar was important to farmers as a way to regulate agricultural activities. Having a well-regulated yearly cycle also indicated that the empire was well-governed, and that Heaven and Earth were in harmony. It was the emperor’s astronomers who were responsible for preparing the calendar.