Why doesn't sunrise shift as we revolve around the sun (ignoring seasonal variations - so at the equator) If the Earth rotates at a constant speed why doesn't sunrise change as we orbit the Sun?
For example if viewing the Earth's orbit from above at time N let's assume the Earth is at the 3 'o' clock position and so the point on the Earth's surface at the equator perpendicular to the Sun would be in daylight (~12pm local time) let's call this point X (would be at the Earth's 9 'o' clock position).
Six months later the Earth would be at the 9 'o' clock position in its' orbit and assuming the Earth has completed exactly 182 full rotations that point X will again be at the Earth's 9 'o' clock position but would now be facing away from the sun therefore it would be dark but exactly 182 days have passed so it should be (~12pm local time).
I'm probably overlooking something obvious but hoping someone can explain why this obviously isn't what happens in reality.
Many thanks.
This shift is already included in a &quot;day&quot;.
24 hours is already the time from sunrise to sunrise, meaning the Earth has performed a full rotation, plus a little bit more since it has moved along a degree in its orbit. That's solar time, the common usage of a &quot;day&quot;.
The time the Earth needs to rotate exactly once,so that a star is in the same position in the sky, is a sideral day. It's slightly shorter at 23 hours 56 minutes and 4 seconds.
You can convert between them based on the fact that there's one less solar day than sideral days in a year:
$$d_{sideral} = \frac{year}{\frac{year}{d_{solar}} + 1}$$
Note that the difference between a solar and a sideral day is far from the only subtility arising from the Earth's orbit.