<p>Sunrise and sunset does not vary much at the equator, but at higher latitudes, they can vary widely near the summer and winter equinoxes. Consider the case in which the tilt is zero, the poles are exactly perpendicular to the ecliptic, days and nights would be exactly the same, exactly 12 hours each. Or, if we could lay the Earth exactly on its side, the poles are along a line within the ecliptic. We would then have 24 hours of daylight in the summer and 24 hours of night in the winter. The Arctic and Antarctic circles would coincide with the equator. At larger pole tilts, summer daylight hours would be longer, winter daylight hours shorter. Likewise, with the poles more perpendicular to the ecliptic, summer daylight hours would be a bit less and winter hours would be a bit more than the Earth with the larger tilt.
OK, now that you are thoroughly confused, at some latitude, and at 23° tilt, daylight hours in the winter is roughly 9 hours and summer daylight hours is about 15 hours. If the tilt is, let’s say 15°, winter hours might be 10 hours and summer hours might be 14 hours. If we could lay the Earth down more like 30°, winter daylight hours might be 6 or 7 hours, and summer daylight hours might be more like 18 or 20 hours.</p>

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2024-11-04T03:02:52.067Z
The question is not asking about the variation of sunrise times during the year. It's asking about an apparent difference on sunrise times on the same date in different years from a table/source the OP was using.
notovny
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2024-11-04T01:28:54.370Z
2024-11-04T01:28:54.370Z
Pogo
<p>Using the US Navy data since 1700, I see a change in the sunrise times between then and 2024. It seems to be several minutes different at the same location on Earth. Does this suggest a shift in the axis of the planet?</p>

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2024-11-02T16:13:29.830Z
Our calendar is synched to the March equinox, but that means the date of perihelion drifts. So the speed of Earth in its orbit also drifts relative to the date, and that affects the time of sunrise, etc. I have some info here: https://astronomy.stackexchange.com/a/49605/16685
PM 2Ring
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2024-11-04T03:01:36.190Z
Question: Could you give examples of the time discrepancy you're seeing? Because the location that would become the United States switched from the Julian Calendar to the Gregorian calendar in 1752 (dropping 11 days from the calendar).  If your source is using the Julian calendar dates for 1700, and the Gregorian Calendar dates for 2024, that's probably the reason for your discrepancy; e.g. June 1 1751, Julian Calendar is about 11 days further from the Vernal Equinox in 1751 than June 1 1753, Gregorian Calendar was to  the Vernal Equinox  in 1753.
notovny
<orbit><history><sunrise>
Does a changing Earth's axis affect sunrise times on a given date?
Star Man
# Does a changing Earth's axis affect sunrise times on a given date?

(Asked by: username_0 on 2024-11-02)

Using the US Navy data since 1700, I see a change in the sunrise times between then and 2024. It seems to be several minutes different at the same location on Earth. Does this suggest a shift in the axis of the planet?

**Tags:** orbit, history, sunrise

> **Comments:**
> **username_1**: Our calendar is synched to the March equinox, but that means the date of perihelion drifts. So the speed of Earth in its orbit also drifts relative to the date, and that affects the time of sunrise, etc. I have some info here: https://astronomy.stackexchange.com/a/49605/16685  
> **username_2**: Question: Could you give examples of the time discrepancy you're seeing? Because the location that would become the United States switched from the Julian Calendar to the Gregorian calendar in 1752 (dropping 11 days from the calendar).  If your source is using the Julian calendar dates for 1700, and the Gregorian Calendar dates for 2024, that's probably the reason for your discrepancy; e.g. June 1 1751, Julian Calendar is about 11 days further from the Vernal Equinox in 1751 than June 1 1753, Gregorian Calendar was to  the Vernal Equinox  in 1753.  

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## 1 answers

### Answer by username_3 on 2024-11-04. Score: -1

Sunrise and sunset does not vary much at the equator, but at higher latitudes, they can vary widely near the summer and winter equinoxes. Consider the case in which the tilt is zero, the poles are exactly perpendicular to the ecliptic, days and nights would be exactly the same, exactly 12 hours each. Or, if we could lay the Earth exactly on its side, the poles are along a line within the ecliptic. We would then have 24 hours of daylight in the summer and 24 hours of night in the winter. The Arctic and Antarctic circles would coincide with the equator. At larger pole tilts, summer daylight hours would be longer, winter daylight hours shorter. Likewise, with the poles more perpendicular to the ecliptic, summer daylight hours would be a bit less and winter hours would be a bit more than the Earth with the larger tilt.
OK, now that you are thoroughly confused, at some latitude, and at 23° tilt, daylight hours in the winter is roughly 9 hours and summer daylight hours is about 15 hours. If the tilt is, let’s say 15°, winter hours might be 10 hours and summer hours might be 14 hours. If we could lay the Earth down more like 30°, winter daylight hours might be 6 or 7 hours, and summer daylight hours might be more like 18 or 20 hours.

> **Comments:**
> **username_2**: The question is not asking about the variation of sunrise times during the year. It's asking about an apparent difference on sunrise times on the same date in different years from a table/source the OP was using.  

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