I read an article over on EarthSky titled "At mid-northern latitudes, latest sunsets of the year in late June", by Bruce D McClure.
He says that "At and around the equinoxes, solar days are shorter than 24 hours, yet at the solstices, solar days are longer than 24 hours." and "The latest sunsets come after the summer solstice because the day is more than 24 hours long at this time of the year."
I don’t doubt this is true. But I would like to better understand why... Obviously it's not a difference in the rotation speed of the earth. I fully understand why the angle of the earth makes longer days in the north hemisphere during summer (in the northern hemisphere). But I also don’t see why the latest sunset is past the solstice. My suspicion is that it has to do with the orbit of the earth being elliptical and how the orbit of the earth around the sun would make a small effect on the time that the rotation takes to get the sun back to exactly the same point as the previous day. If the orbit was a perfect circle then the effect of the earth moving around the sun would have the same effect on the slightly less than 360 rotation that is needed to get back to the same earth sun angle.
Since the earth rotation is the same direction as the revolution, the revolution makes the time needed to get to the same angle less and a faster revolution should mean a faster time to get to that angle.
Earth is furthest from the sun in July, closest in January. So is the earth going around the sun faster in July? Perhaps a better question would be does the earth change angle to the sun any faster as a change in speed might counter the orbit angle (at the narrow point of the ellipse but slower?). Sorry it's been a long time since I’ve thought about physics like that.
So... I'm hoping someone can verify or set me straight regarding the physics of a planet going around the sun and give me a better mental model for why the date of the latest sunset is after the summer solstice.
Thanks in advance for polite answers.