[ntp:questions] Leap second question

Stephen Yu syu at symmetricom.com
Wed Mar 20 18:22:35 UTC 2013


I guess I did not state my question clearly enough. I would like to confirm this was not an omission in the code to check for condition that can lead to "sys_leap = LEAP_DELSECOND". Searching the code, it seems "sys_leap" can only be LEAP_NOTINSYNC, LEAP_NOWARNING, or LEAP_ADDSECOND.


-----Original Message-----
From: Chuck Swiger [mailto:cswiger at mac.com] 
Sent: Wednesday, March 20, 2013 10:18 AM
To: Stephen Yu
Cc: questions at lists.ntp.org
Subject: Re: [ntp:questions] Leap second question


On Mar 19, 2013, at 6:15 PM, Stephen Yu wrote:
> The question is why "sys_leap = LEAP_ADDSECOND" is unconditional. Is this based on the prior knowledge that earth always rotates slower? In other word, could it ever be "sys_leap = LEAP_DELSECOND"?

Over the long term, the earth's rotation is slowing over time primarily due to tidal friction from the moon.  It's possible for a large-scale event like a big earthquake or meteor strike to increase the earth's rotational speed slightly, but even a ~9.0 richter earthquake resulted in a speedup of only a few milliseconds.


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