Local Time vs Solar Time – Difference and Comparison

What is Local Time?

Local time is the time of day in a particular location, based on the time zone in which the site resides. Local time is essential for daily life, business operations, communication, and leisure activities. It plans, coordinates activities, sets schedules, and even determines when to wake up and sleep.

Local time is based on the Sun’s position in the sky, as it moves around the earth day and night. This movement of the Sun is measured in units of time called time zones. These time zones are separated by fifteen degrees of longitude, with the time zone at the Prime Meridian in Greenwich, England, set as the standard. The time zone in each location is determined by the number of hours ahead or behind the Prime Meridian.

Time zones are based on the earth’s rotation but can be affected by changes in the earth’s orbit and other astronomical events such as solar eclipses.

Local time is essential for people worldwide, and one must be aware of the time zone in which one is located, helping with communication and scheduling and providing a sense of identity and belonging. The ability to hold track of time is a fundamental part of everyday life, and staying in sync with the rest of the earth is essential.

What is Solar Time?

Solar time is the measure of time based on the place of the Sun in the sky. It is measured by the Sun’s apparent movement across the sky and is the basis for measuring time for many cultures and societies worldwide.

Solar time is measured by the angle of the Sun from the observer’s position, with 0° being the point of noon when the Sun is at its highest point. The rise of the Sun is measured in degrees, minutes, and seconds, and the time is then calculated based on this angle.

Solar time is calculated in local time, then converted to standard time using a time zone. Solar time is used to determine the time of day, the length of day and night, the start & the end of daylight savings time, and other seasonal events. It is also used to calculate the date of certain astronomical events, such as the solstices and equinoxes, as well as the timing of religious festivals and holidays.

In addition to its practical uses, solar time is also used to define the length of a day and the start and end of a year.

Difference Between Local Time and Solar Time

  1. Local time is more accurate than solar time, based on a consistent, measurable unit of time.
  2. Local time is adjusted often to accommodate Daylight Saving Time, while solar time is not.
  3. Local time is legally recognized in many countries, while solar time is not legally recognized.
  4. Local time can affect the behavior of plants and animals, while solar time does not.
  5. Local time can vary from solar time in terms of how much daylight is available on a given day.

Comparison Between Local Time and Solar Time

Parameters of ComparisonLocal TimeSolar Time
BasisLocal time is based on the 24-hour clock.It is based on the position of the Sun in the sky.
CalculationLocal time is calculated using a clock.Solar time is calculated using the Sun’s position.
Reference PointLocal time uses the Greenwich meridian.Solar time uses Sun’s position.
Time ZonesLocal time can vary depending on a person’s time zone.Solar time is the same everywhere.
VarianceLocal time can vary from solar time by up to 16 minutes due to geographical location.Solar time is always the same in any given area.


Solar radiation and its variation in time | SpringerLink