UNIX for Dummies Questions & Answers

Problem solved. The Earth is no longer losing time, yet scientist still add an extra leap second each year....

Earth changes its spin, baffles scientists
Thursday, January 1, 2004 Posted: 10:16 AM EST (1516 GMT)

BOULDER, Colorado (AP) -- In a phenomenon that has scientists puzzled, the Earth is right on schedule for a fifth straight year.

Experts agree that the rate at which the Earth travels through space has slowed ever so slightly for millennia. To make the world's official time agree with where the Earth actually is in space, scientists in 1972 started adding an extra "leap second" on the last day of the year.

For 28 years, scientists repeated the procedure. But in 1999, they discovered the Earth was no longer lagging behind.

At the National Institute for Science and Technology in Boulder, spokesman Fred McGehan said most scientists agree the Earth's orbit around the sun has been gradually slowing for millennia. But he said they don't have a good explanation for why it's suddenly on schedule.

Possible explanations include the tides, weather and changes in the Earth's core, he said.

The leap second was an unexpected consequence of the 1955 invention of the atomic clock, which use the electromagnetic radiation emanated by Cesium atoms to measure time. It is extremely reliable.

Atomic-based Coordinated Universal Time was implemented in 1972, superseding the astronomically determined Greenwich Mean Time.

Leap seconds can be a big deal, affecting everything from communication, navigation and air traffic control systems to the computers that link global financial markets.Leap Second Story

But everyone seems to have skipped the question as to why their Server is losing time...

System clocks on computers are very poor time pieces - they are notoriously inaccurate - hence the need for NTP services. It is not uncommon for a computer's system clock to be off by minutes per month.

Including you. You just restate that computers have poor clocks.


The reason is cost. An accurate clock would add from $200 to $50000 to the cost of the computer depending on how much accuracy you wanted. Computer hardware manufacturers are competing heavily in the cost of the system. They aren't willing to spend much money on a super accurate clock.

People who need accurate time just use ntp which can keep you accurate to a fraction of a second.


And to put on my moderator hat... It's hard to know where to draw the line in a thread like this. And yes, I'm as guilty as anyone. This stuff is interesting, but we are not a geophysics site. So a lengthy discussion of of the anomilies in Earth's rotation will quickly get way out of bounds and will accomplish nothing. Let's try to keep stuff computer related. Thanks.