How is Universal Time Measured? Best Guide 2023

Although, Time plays an important role in our lives. We use time measurements for scheduling meetings, traveling, or interacting with someone. Especially when the other person has a different time zone. In addition, In this blog post, we will discuss such a time zone named “UTC” (Universal Time Zone) and How is Universal Time Zone Measured? Have a look at that, it won’t take much time.

How is Universal Time Measured?

There are multiple ways to measure UTC time. Have a look below:

Earth Rotation And Solar Time

Earth rotations were the earliest form of timekeeping. Apparent solar time which is also known as solar time, was used to know the position of the sun in the sky. Also, the time was taken by the sun’s position by measuring its time differences while returning to the same position. Moreover, by doing so, the time was divided into 24 hours.

After some time, just because of advanced astronomy, we came to know that we cannot rely on the earth’s rotation due to some factors. These factors can be gravitational interactions with the moon. After this, the astronomists realized that there must be other standardized things to measure accurate timekeeping.

International Atomic Time (TAI)

Without a doubt, UTC is based on the TAI (International Atomic Time). Also, UTC is maintained by highly accurate atomic clocks all over the world. Besides this, the universal time zone is also measured by the solar time with a miner adding or subtracting the leap seconds.

The purpose of adding or subtracting keeps a maintained difference between UTC and astronomical time. Also, UTC remains within 0.9 seconds of TAI.

Measurement By Stars

Besides measuring time by solar time standard, UTC time is also measured by the stars. Measuring time by stars ensures a higher standard of accuracy. As the earth moves around its axis, the sun and other fixed planets that appeared move around the sky. Only modern technologies and gadgets allow us to know the UT with high accuracy.

There is a method to measure the UTC time with the help of stars known as VLBI (Very Long Base Interferometry). In addition, In VLBI, a group of radio signals are transmitted to objects like quasars by radio telescopes. This method let us measure a high precision in less than 4ms (milliseconds).

What is the Difference Between Sidereal Time Vs Solar Time?

Although, the sidereal time and solar time are not the same. Have a look below to know the sidereal and solar time.

Sidereal Time

The time that is measured with the help of stars is known as Sidereal Time. In addition, In this method, the measurements are converted mathematically by the scientist to know the UT. It measures a period of time the earth takes a full rotation around its axis in relation to the fixed objects.

Solar Time

This is a universal time. It is measured by the full period of rotation of the earth in relation to the sun. Also, Solar Day is a little bit longer than sidereal day an average of 4 minutes.


How is universal time measured accurately?

There are multiple advanced ways to calculate universal time accurately. One of the most accurate ways to calculate UT is by VLBI (very long base interferometry). In this method, the radio signals are transmitted from the celestial bodies by radio telescopes to observe signals. It achieves accurate precision within milliseconds.

What are atomic clocks?

These are the advanced devices that observe precision and accuracy. Through these devices, the time is measured by the vibration of atoms such as rubidium and cesium.

Why are leap seconds added to the universal time coordinate (UTC)?

Usually, the leap seconds are added to universal time coordinates to calculate and maintain the slow rotation of the earth to keep atomic time and the earth time in sync.

Are the atomic clocks accurate?

An atomic clock or time is reliable for accurate time measurement. Also, it can maintain an accuracy of billionths of a second in a single day.

What is TAI (International Atomic Time)?

It is a time scale that relies on atomic vibrations. The benefit of using TAI is that it doesn’t consider Earth’s rotation.

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