The leap second is on the chopping block — and timekeeping could change forever - WPSD Local 6

(CNN) — When the sun hits its highest point over the meridian line that travels north and south from the 351-year-old Royal Observatory Greenwich in London, it’s noon Greenwich Mean Time, a tangible and physical reference point that helped establish the world’s time zone system. Timekeeping has long relied on Earth’s spin and location of the sun or moon in the sky. Before observatories such as Greenwich, humans used sundials — essentially a stick in the ground that casts shadows as the sun moves overhead. But this ancient link between Mother Earth and today’s clocks looks set to be severed. International timekeepers are on track to vote Thursday on a proposal to eliminate what’s known as a leap second — a tiny, but many say important, link between Earth’s rotation and the world’s time standard used in critical infrastructure such as telecommunications, power grids and computers.

Inserted into global clocks 27 times since 1972, the leap second essentially allows two time systems to run in sync: astronomical time, long anchored by Earth’s rotation and measured by observatories, and Coordinated Universal Time, or UTC, the global standard that’s set by ultraprecise atomic clocks