Question

Columbus, Ohio, is in the Eastern Time Zone, for which the civil

time is equal to the mean solar time along the 75 degrees W meridian of
longitude.
(a)Ignoring daylight saving time for the moment, are there any days
of the year when civil noon (as shown by a clock) is the same as
apparent local noon (as shown by the Sun) in the city of Columbus?
If so, what day or days are they?
(b)Daylight savings time advances the clock by one hour from the second Sunday in March to the first Sunday in November (“Spring forward, fall back”). When daylight savings time is in effect, are there any days of the year when civil noon is the same as apparent local noon in the city of Columbus? If so, what day or days are they?

Answer 1

In Columbus, Ohio, civil noon and apparent local noon may coincide around the equinoxes, but the exact match would require an adjustment due to the city's longitude. Due to daylight saving time advancing clocks by one hour, there are no days when civil noon corresponds to apparent local noon during this period.

Step-by-step explanation:

In Columbus, Ohio, there may be days when civil noon and apparent local noon, as shown by the Sun, coincide. This is because civil time is usually kept uniform across time zones, but there is a specific longitude within each time zone where sundial time (or apparent local noon) exactly matches clock time. Elsewhere, a correction must be added. Since Columbus is not situated exactly on the 75 degrees W meridian that defines Eastern Standard Time, actual solar noon is slightly different than clock noon year-round.

During the days around the equinoxes, time differences between solar and standard time minimize due to the Earth's orbit and axial tilt, making it the most likely time when civil noon could coincide with apparent local noon. However, because of the discrepancy caused by longitude, this may not be precise and would require calculation of the exact difference for Columbus.

When daylight saving time is in effect, clocks are advanced by one hour, which means that civil noon is not the same as apparent local noon. However, since daylight saving time shifts the clock, it creates an even greater discrepancy between the sun's position and the civil time. As such, there are no days when civil noon is the same as apparent local noon while daylight saving time is in effect in Columbus, Ohio.