Does the Time of Sunset (Sunrise) Change Over Time Given a Fixed Location and Consistent Atmospheric Conditions? Assumming a fixed location, clear skies, and consistent atmospheric conditions, does the sunset (sunrise) time change over time?
For example, sunset on February 3, 2021 in Tel-Aviv, Israel, is indicated to be 5:17pm. This is a rounded figure I'm sure. Thus, within a minute, would this stated sunset time have been any different historically---or will it be expected to change in the future?
I know that the length of the tropical year is gradually decreasing overall---does this have any effect on the time of sunset (sunrise)?
Thank you.
Shalom! Strictly speaking, yes, the time of sunset does change, but the amount of change is imperceptible to humans over a lifetime. The change is due to the slowly varying obliquity of the Earth on its axis, the slowly varying eccentricity of Earth’s orbit around the Sun, and other such cyclic or secular changes.
Other than that, you’ll notice a slight change from one year to the next, as the year doesn’t last exactly 365 days. This is a four-year cycle, and the difference is around one minute, I would say, on average, depending on the time of the year—for example, when there is less of a difference in sunrise/sunset times from one day to the next, the difference between the same date of two successive years is lesser than for dates when there is a large difference between one day and the next.