Actually, the reason for the difference in the time of moon sighting is the movement of the Earth and the Moon. The Earth continuously rotates on its axis and the Moon revolves around the Earth. Due to the movements of these two, the moon is not visible everywhere at the same time.

For example, when the Earth rotates, a part of it comes in the direction of the Sun and Moon’s light first, while the rest comes later. This is the reason why the moon is visible with a difference of a few minutes in different cities on the same day.

Apart from this, time zone is also a big reason. Even though India runs on the same standard time (IST), the country is geographically very large.

In western cities, sunset and moonrise occur slightly later than in eastern cities. For example, in Kolkata the moon may be seen before Delhi, while in Jaipur or Ahmedabad it may be seen a little later. Sometimes this difference even reaches 15 to 30 minutes.

The tilt of the Earth also plays a role in this astronomical difference. The Earth is tilted on its axis by approximately 23.5 degrees, due to which the direction of rise and set of the Sun and Moon keeps changing throughout the year. This is the reason why the position and time of rise of the moon on the day of Karva Chauth is slightly different every year.

Now talking about the movement of the Moon, the Moon completes its revolution around the Earth every 27.3 days and during this time it rises with a delay of about 50 minutes every day. This delay also affects the local moonrise time of every city.

Therefore, if you are observing the fast of Karva Chauth and wondering why the moon rises late in your city, then know that it is all due to the natural movement and geographical position of the Earth and the Moon.