Leap Second

Source-This post on Leap Second is based on the article “Melting ice sheets may postpone need for ‘negative leap second’” published in “The Indian Express” on 1st April 2024.

Why in the News?

According to a recent study, Earth’s changing rotation, influenced by factors such as climate change and geological shifts, may result in clocks skipping a second, potentially leading to the need for a “negative leap second” around 2029.

What is Leap Second?

1. About- It is a one-second adjustment used to address the gradual slowdown of Earth’s rotation, caused by the continuous melting and refreezing of ice caps.

2. Introduced by– International Earth Rotation and Reference Systems Service in 1972.

3. Addition of leap second– It is periodically added to Coordinated Universal Time (UTC) to keep clocks worldwide synchronized with atomic time and to compensate for the Earth’s gradually slowing rotation. So far, 27 positive leap seconds have been added.

4. Reason for addition– Earth’s rotation on its axis is not consistent; it can speed up or slow down due to factors like the moon’s gravitational pull, which leads to ocean tides.

5. Usual date of addition– A leap second is typically added either on June 30th or December 31st.

What is Negative leap Second?

1. About– It is a second that is removed from our clocks to maintain synchronization with the Earth’s rotation. So far, no negative leap second has been needed because the Earth’s rotation has generally been slightly slower over the past few decades.

2. Administration– The International Earth Rotation and Reference Systems Service (IERS) oversees Earth’s rotation and determines when to add or subtract a leap second.

3. Recent impact– Recently, because the Earth has been spinning faster than usual, timekeepers thought about using negative leap seconds for the first time.

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