Talk:1514: PermaCal

Explain xkcd: It's 'cause you're dumb.
Revision as of 10:41, 20 April 2015 by (talk) (leap seconds adjust for time of day, not year.)
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In Megan's response, the "h" in "19th" is backwards. 05:47, 20 April 2015 (UTC)

I'm pretty sure that's a mistake since lowercase letters normally aren't used. Mikemk (talk) 05:49, 20 April 2015 (UTC)
Looks like he forgot the line on the upper left. He used the capital 19TH for Cueball. 07:24, 20 April 2015 (UTC)
I think it's intentional. All the H's after a T have shortened upperleft lines. Probably for nice ToaVin (talk) 10:12, 20 April 2015 (UTC)

Leap seconds have nothing to do with the length of the year: corrected. 07:49, 20 April 2015 (UTC)

"Leap seconds normally account for the differences in the length of our 24 hour day and the time taken for the world to rotate 360 degrees on its axis" - this sentence mixes two unrelated concepts. First, a day is not a rotation of 360 degrees. Because the Earth also orbit the sun, the rotation from noon one day to noon the following day is a bit more than 360 degrees (360.9856 or so) (rotation measured relative to the stars) - this is why constellations appear to move throughout the year. Second, leap seconds are required because the leap day corrections of the Gregorian calendar are good, but not perfect, at matching the difference between Earth orbits (years) and Earth rotations (days). Every so often, a small correction is required. The corrections are not regular because the causes of the drift are numerous: tidal effects, orbital eccentricity, the underlying (small) flaws in the calendar, etc. I have not made any changes in the explanation. -- 08:41, 20 April 2015 (UTC)

While you are true on one part, that Earth doesn't take 24 hours to rotate 360 degrees (it takes around 23 hours and 56 minutes if I recall correctly), leap seconds are used to account for differences between 24 hours and a solar day. If it was used to adjust the length of the year the time of day would drift, it would also be fairly pointless as the leap days take us out by 1/4 of a day. 10:41, 20 April 2015 (UTC)