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
You are confusing “noon” with the time on your clock. In many parts of the world the clock is shifted during “summer time” to make more hours of light after lunch, when it’s useful, and fewer hours before people get up, when it’s “wasted”. The noon that’s when the sun is highest in the sky is a local time that’s not a function of clock settings. Time zones are a useful approximation of the actual local time, but the approximation is subject to these manipulations.
Daylight saving time.
Winter mid day is equidistant from both dawn and dusk. In the summer, the clocks are put an hour forwards so that mid day is actually 1 o’clock. If the sun sets at 10pm, it will rise 9 hours before 1PM which is 4am or 3am and 9pm in winter hours.
The sun isn’t at it’s relative peak at noon. The time of noon and the time the sun is the highest in the sky are not set to the same, exactly because us humans tend to enjoy having sunlight somewhat later in the day.
Where I live, during the summer, the sun is actually at its highest point around 1:30pm.
“Noon” is just a number on a particular moment. The Sun and the rest of astronomy doesn’t care about it.
[Here’s a table of sunrise and sunset times in Chicago.](https://www.timeanddate.com/sun/usa/chicago). On September 1st, there were 13 hours and 6 minutes of daylight. The sun rose at 6:16 AM and set at 7:17 PM. You’ll note that’s an hour more afternoon.
“Solar Noon” is when the sun was ACTUALLY at its highest point. That was at 12:50 PM. So if you’d have observed the sun at noon on September 1st in Chicago, you’d have noticed it was *not quite* at its peak yet. You’d have to wait about an hour.
All of these things combine to mean we quite often have more daylight after noon than before. SOME of this is because of daylight savings. But since almost every day of the year is more or less than 12 hours, it’s pretty rare that the “noon” on our 24-hour system lines up perfectly with solar noon.
What we call noon is generally *not* when the sun peaks. Before time zones and daylight saving time, it used to be, but it isn’t anymore.
Time zones choose a specific line of longitude and let noon follow the old rules on that line of longitude. The time zone, however, typically extends *westward* from that line, and because the earth rotates to the east, the sun rises later and sets later the further west you are of the time zone line. If you happen to be near the western edge, this can be almost a full hour later. So daytime on, say, the autumn equinox isn’t 6 am to 6 pm, it’s more like 6:45 am to 6:45 pm.
Daylight saving time messes with this further by making the *clock* an hour later, essentially gaslighting us into believing it’s later in the day than it actually is. So now, during it, daytime runs 7:45 am to 7:45 pm and the sun is highest at 1:45 pm and when the clock reeds “noon”, it’s what the old rules would have called 10:15 am.
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.
The sun generally *isn’t* at its peak at noon. Time zones are large, the sun cannot possibly be simultaneously directly overhead at 12:00 in two cities hundreds of miles apart.
Many places have daylight savings or summer time where they shift the clock an hour.. so afternoon is longer at the expense of evening.
The world is split in 24 time zones, each one being an hour of rotation or 15 degrees wide. This is not accidental.
Early navigation using an accurate clock will show that if a clock is set at noon at the British naval observatory, (prime meridian 0 degrees) if you travel any where on earth, at “Solar noon” the clock will show a “time” that is the “amount” of East/west rotation from the prime meridian.
So at solar noon in Chicago the clock might read around 6:48am ( around 87 degrees west)
In Paris it would read something like 12:05pm (2 deg east)
In Tokyo it would read 9:20pm. (140 degrees east )
( my math might not be exact)
Solar noon is not the same as noon on a clock. That only happens during standard time **at the centre of a time zone**. (*To locate your time zone centre, find the number of hours you are ahead or behind of UTC and multiply that by 15 to get the longitude*).
If there is daylight saving time in effect, **solar noon will be delayed**. If you are too far **east** in your time zone, solar noon will be **earlier** than noon on your clock. If you are too far **west** in your time zone, solar noon will be **later** than noon on your clock.
For instance, Vancouver, British Columbia is approximately three degrees west of its time zone centre, and it is on daylight saving time. Sunrise today is at 06:53 and sunset at 19:22. The average of those is 13:08.
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