Difference between revisions of "Talk:1514: PermaCal"

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Not unrelated concept. Just not fully understood. Rotate 360 degrees is a simple way of putting things that ignores the diffrence between solar days and sidereal days. Incorrect not because someone doesn't understand the topic being discussed but because someone hasn't studied astronomy or seriously thought about how the movement of the Earth effects the length of the day--[[Special:Contributions/108.162.237.183|108.162.237.183]] 13:00, 20 April 2015 (UTC).
 
Not unrelated concept. Just not fully understood. Rotate 360 degrees is a simple way of putting things that ignores the diffrence between solar days and sidereal days. Incorrect not because someone doesn't understand the topic being discussed but because someone hasn't studied astronomy or seriously thought about how the movement of the Earth effects the length of the day--[[Special:Contributions/108.162.237.183|108.162.237.183]] 13:00, 20 April 2015 (UTC).
 
There is some confusion between the different types of astronomical time:  a day in mean solar time is 24 hours, with a difference of + or - up to 1 second (compared to time on an atomic clock), in apparent solar time is 24 hours + or - up to 30 seconds, and in mean sidereal time is 23 hours, 56 minutes, 4.0916 seconds (according to Wikipedia), and there is one extra sidereal day (about 366.25) in a sidereal year. [[User:The Dining Logician|The Dining Logician]] ([[User talk:The Dining Logician|talk]]) 13:55, 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.[[Special:Contributions/108.162.250.175|108.162.250.175]] 10:41, 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.[[Special:Contributions/108.162.250.175|108.162.250.175]] 10:41, 20 April 2015 (UTC)
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Apropos a "permanent calendar", Isaac Asimov proposed just such a calendar. http://calendars.wikia.com/wiki/World_Season_Calendar This web page unfortunately doesn't go into details, but there were several advantages. The same calendar is used for all years, your birthday is always on the same day of the week, no need to remember "30 days hath Sept. ...", and several other advantages I can't remember right now. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 12:45, 20 April 2015 (UTC)
 
Apropos a "permanent calendar", Isaac Asimov proposed just such a calendar. http://calendars.wikia.com/wiki/World_Season_Calendar This web page unfortunately doesn't go into details, but there were several advantages. The same calendar is used for all years, your birthday is always on the same day of the week, no need to remember "30 days hath Sept. ...", and several other advantages I can't remember right now. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 12:45, 20 April 2015 (UTC)
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There is some confusion between the different types of astronomical time:  a day in mean solar time is 24 hours, with a difference of + or - up to 1 second (compared to time on an atomic clock), in apparent solar time is 24 hours + or - up to 30 seconds, and in mean sidereal time is 23 hours, 56 minutes, 4.0916 seconds (according to Wikipedia), and there is one extra sidereal day (about 366.25) in a sidereal year. [[User:The Dining Logician|The Dining Logician]] ([[User talk:The Dining Logician|talk]]) 13:55, 20 April 2015 (UTC)
  
 
It seems like our collective favorite word just might be "portmanteau" [[User:YourLifeisaLie|The Goyim speaks]] ([[User talk:YourLifeisaLie|talk]]) 13:42, 20 April 2015 (UTC)
 
It seems like our collective favorite word just might be "portmanteau" [[User:YourLifeisaLie|The Goyim speaks]] ([[User talk:YourLifeisaLie|talk]]) 13:42, 20 April 2015 (UTC)

Revision as of 13:58, 20 April 2015

In Megan's response, the "h" in "19th" is backwards. 108.162.214.239 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. 173.245.48.60 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 http://www.explainxkcd.com/wiki/index.php/kerning ToaVin (talk) 10:12, 20 April 2015 (UTC)

Leap seconds have nothing to do with the length of the year: corrected. 108.162.249.162 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. --141.101.104.66 08:41, 20 April 2015 (UTC)

Not unrelated concept. Just not fully understood. Rotate 360 degrees is a simple way of putting things that ignores the diffrence between solar days and sidereal days. Incorrect not because someone doesn't understand the topic being discussed but because someone hasn't studied astronomy or seriously thought about how the movement of the Earth effects the length of the day--108.162.237.183 13:00, 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.108.162.250.175 10:41, 20 April 2015 (UTC)

Do we know for sure that this comic was released on a Sunday - the 19th instead of the 20th? The first entry in this page is from the 20th. Of course there are some references to the 19th, but then again it is obvious that it is on the 20th that Megan asks. Anyone who can find out if this is the correct date, or just a mistake by someone who misunderstood something based on the dates in the comic? --Kynde (talk) 11:19, 20 April 2015 (UTC)

Apropos a "permanent calendar", Isaac Asimov proposed just such a calendar. http://calendars.wikia.com/wiki/World_Season_Calendar This web page unfortunately doesn't go into details, but there were several advantages. The same calendar is used for all years, your birthday is always on the same day of the week, no need to remember "30 days hath Sept. ...", and several other advantages I can't remember right now. --RenniePet (talk) 12:45, 20 April 2015 (UTC)

There is some confusion between the different types of astronomical time: a day in mean solar time is 24 hours, with a difference of + or - up to 1 second (compared to time on an atomic clock), in apparent solar time is 24 hours + or - up to 30 seconds, and in mean sidereal time is 23 hours, 56 minutes, 4.0916 seconds (according to Wikipedia), and there is one extra sidereal day (about 366.25) in a sidereal year. The Dining Logician (talk) 13:55, 20 April 2015 (UTC)

It seems like our collective favorite word just might be "portmanteau" The Goyim speaks (talk) 13:42, 20 April 2015 (UTC)