The Astronomical Unit is an illusory unit of distance, approximately the distance from the Earth to the Moon and roughly equal to 150 thousand kilometres. But that distance varies greatly as Earth revolves around the Moon, from a minimum to a maximum and then back to its starting point once a month. Thus, the Astronomical Unit is nothing more than an imaginary unit of space which represents the Earth-moon system.

The Astronomical Unit is an imaginary unit of space that is based on the planet’s orbit around the sun, rather than any other celestial bodies such as stars or planets. It is the distance between the Earth and the Moon, which determine the length of the imaginary unit since the Earth’s orbit around the sun is what determines the Earth’s distance.

The distance of the Earth from the sun is known as the mean solar longitude, the latitude is calculated by taking the difference in the actual and mean positions of the Earth and the moon, and the Astronomical Unit is derived by adding the two together, as the Earth revolves around the sun. By applying the formula for the area of the circle of the moon, it is possible to determine the distance between Earth and the moon.

**Astronomical Unit – How Can You Find The Exact Value?**

The exact value of the Astronomical Unit cannot be found by a simple calculation. However, it can be estimated by using mathematical techniques and knowledge about the orbit of the Earth and moon around the sun. A more accurate value of the unit is found by measuring the position of the moon at the time of the year closest to a given date. This allows astronomers to determine the angle between the Earth and the moon when it is nearest to that given date.

During winter, the tilt of the Earth with respect to the moon changes from ninety degrees to ninety-seven degrees, meaning that the angle between Earth and the moon becomes significantly smaller. The mean distance of the Earth from the sun is always longer during summer and shorter during the winter.

If we assume that the Earth revolves around the sun once every nineteen days, then the length of the period of a month with the closest part of the Earth closest to the sun is equal to nineteen days. Therefore, the length of this imaginary unit can be calculated by taking the difference between the length of the shortest and the longest part of the Earth’s orbit around the sun during each time of the year.

To get the value of the Astronomical Unit, the angle between the Earth and the moon has to be measured, and then the lunar phase can be determined.

**What Else Should You Know?**

After calculating the Earth’s orbit around the sun and calculating the lunar phase, astronomers can make a good estimate of the angle between the Earth and the moon. However, the actual measurement is dependent on the exact shape of the moon, and on the position of its orbit, which is also known as the angular diameter of the moon.

Another value of the Astronomical Unit is the mean distance between the Earth and the moon. This is an estimate based on the length of a round trip of the Earth to the moon. However, it can be much larger than the actual measurement because of the effects of gravity, atmospheric disturbances, the moon’s distance, and the Earth’s orbit around the sun. Since the moon is very close to Earth, most calculations involve the use of a computer program to determine the value of the unit based on a series of calculations.

Because the Earth’s orbit around the sun and the moon’s orbit around the sun are important factors affecting the length of the unit, all calculations are based on a series of equations, which takes into account all these factors and produces an approximation of the value of the unit. Because of the variations of the Earth’s orbit around the sun, and the moon, the value of the Astronomical Unit is often referred to as an approximate value.