Clocks to chime one second late for 2017

Washington: This year will last a second longer as a “leap second” will be added to the world’s clocks on New Year’s Eve by the timekeepers. The extra second will be inserted at the US Naval Observatory’s Master Clock Facility in Washington, DC at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC) which corresponds to 5:29:59 am Indian Standard Time on January 1.

Historically, time was based on the mean rotation of the Earth relative to celestial bodies and the second was defined in this reference frame. However, the invention of atomic clocks defined a much more precise “atomic” timescale and a second that is independent of Earth’s rotation. In 1970, international agreements established a procedure to maintain a relationship between Coordinated Universal Time (UTC) and UT1, a measure of the Earth’s rotation angle in space.

The International Earth Rotation and Reference Systems Service is the organisation which monitors the difference in the two time scales and calls for leap seconds to be inserted in or removed from UTC when necessary to keep them within 0.9 seconds of each other.

In order to create UTC, a secondary timescale, International Atomic Time (TAI), is first generated; it consists of UTC without leap seconds. When the system was instituted in 1972, the difference between TAI and UTC was determined to be 10 seconds. Since 1972, 26 additional leap seconds have been added at intervals varying from six months to seven years.

• A ‘leap second’ will be added to the world’s clocks on New Year’s eve by timekeepers
• The extra second will be inserted at the US Naval Observatory’s Master Clock Facility in Washington, D.C. at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC)
• UTC corresponds to 5:29:59 am Indian Standard Time on January 1
• Historically, time was based on the mean rotation of the Earth relative to celestial bodies, and the second was defined in this reference frame
• However, the invention of atomic clocks defined a much more precise ‘atomic’ timescale and a second that is independent of Earth’s rotation
• In 1970, international agreements established a procedure to maintain a relationship between UTC and UT1. UT1 is a measure of the Earth’s rotation angle in space
• The International Earth Rotation and Reference Systems Service monitors the difference in the two time scales
• It calls for leap seconds to be inserted in or removed from UTC when necessary to keep them within 0.9 seconds of each other