2005 will last a little longer than usual -- one second to be precise.

A leap second will be added into the world's clocks just before midnight to match up the clocks with the earth's rotation.

This will be the first leap second in seven years and the 23rd since 1972 when an international timekeeping agreement was signed.

Leap seconds are necessary because modern atomic clocks are extremely accurate while the earth's rotation has been slowing down because of tides.

The clocks establish the official time, which is known as Coordinated Universal Time, for the world.

Atomic clocks use electromagnetic radiation emanated by Cesium atoms to measure time. That makes them extremely reliable, and unaffected by the earth's changes.

The leap second syncs up the clocks with the planet's position in space.

"We would get out of sync with the sun," Richard Langley, a University of New Brunswick researcher, told The Globe and Mail.

"In about 600 years, the difference will be half an hour and in about 1,000 years, the difference will be a full hour," he said.

Leap seconds are not without controversy, however. They can affect communications, navigation and air traffic control systems and computer systems that have to be updated.