The International Earth Rotation and Reference Systems Service (IERS), based in Paris, has decided to add an extra “leap” second to the 24 hours of December 31, 2005 (GMT), making the total number of seconds in 2005 not 31,556,926 as in previous years, but 31,556,927 seconds.
Historically, methods for measuring time included water clocks, pendulum clocks, and solar-powered clocks. However, since 1950, experts at IERS have been using a new and more efficient tool for this purpose: atomic clocks, which can measure time with extreme precision—deviating only 1 second every 50 million years.
The International Bureau of Weights and Measures (BIPM), also located in France, has established a network of 250 atomic clocks distributed around the globe to determine International Atomic Time (TAI) and Coordinated Universal Time (UTC). While TAI is calculated based on machinery, UTC is derived from the cycles of the sun’s rising and setting.
Astronomers explain that the Earth’s rotation is gradually slowing down due to tidal forces and the effects of the Moon, resulting in a loss of energy. Although this difference is minimal, it is sufficient to create a discrepancy between TAI and UTC, necessitating occasional adjustments to world time. The adjustment on the night of December 31, 2005, marks the 22nd time this adjustment has been made and potentially the last adjustment in history. The International Telecommunication Union (ITU) is expected to review the discontinuation of the “leap second” in August 2006.