Leap second
Topic: Latitude, Longitude and Time · NCERT: Beyond NCERT
Meaning
A leap second is one extra second added to UTC. The earth's rotation is slightly uneven, but atomic clocks are not. Leap seconds keep UTC within 0.9 second of the earth's actual rotation. 27 leap seconds have been added since 1972. In 2022 the General Conference on Weights and Measures (CGPM) decided to stop adding them by 2035.
Example
The last leap second was added on 31 December 2016. Because India is 5 hours 30 minutes ahead of UTC, it was added in India early on the morning of 1 January 2017.
Don't confuse with
- Leap year: this adds a whole day, 29 February, to the calendar every four years. It keeps the calendar in step with the earth's orbit around the sun, not with its spin.