If the sun is at it’s relative peak at noon, why does it take so much longer to set than it does to rise for at least half of the year?

Question

The closer you are to the date of the summer solstice, it seems to gradually take up to 10 hours for the sun to set. Yet, the sun doesn’t begin to rise at 2am. Why is that?

In: Planetary Science

Answer 1

There is a difference between noon on your clock and “solar noon”, because of time zones. Solar noon is always the time where the sun is highest in the sky at your location, while clock noon is a time that we invented.

Think of this: when we created standard time, we split the earth up into equal zones where the time is the same everywhere in each zone, and there are 24 zones representing 24 hours in a day. By definition each zone is 15 degrees of longitude wide (360 degrees divided by 24 time zones = 15 degrees per zone). At the equator, 15 degrees of longitude is 900 nautical miles (1,035.7 miles, 1,667 km). The clock time is the same everywhere within that distance, but obviously the sun is not directly overhead of every point in the time zone all at the same time. That difference is the difference between clock time and solar time.

The difference is also affected by politics: after we split the globe into 24 time zones, some places wanted to be in the same time zone as some other place (usually because of country borders), so we adjusted some of the zones to accommodate political borders. We also made extra zones for some places that wanted to be a half hour different instead of a full hour, and there are a few time zones that are almost a full day different because of places that wanted to be on a different side of the International Date Line. And then some places do daylight savings time for part of the year so they’re off by another hour. Also, there is the equation of time, which shows that the time of solar noon changes over the course of the year by about half an hour because of changes in the Earth’s orbit.

For any place on earth, solar noon will be halfway between sunrise and sunset (within a few seconds since the day is always getting longer or shorter as the earth moves). You can look up solar time at your location [here](https://gml.noaa.gov/grad/solcalc/). For me, solar noon today is at 1:14PM; sunrise is 6 hours 15 minutes earlier at 6:59AM, and sunset is 6 hours 13 minutes later at 7:27PM.