Weird stuff
- Britain starts DST a week earlier than others
- In the southern hemisphere, they shift DST in the other direction (spring is in November)
- Australia is 8.5 hours ahead
- Somewhere else 5.25 hours
- In Samoa they skipped a day: went from December 29, 2011 to December 31, 2011. They're right at the middle line, so they decided to swap from -12 to +12 so it's nicer to trade with Australia.
- It turns out that countries change time zone fairly often. Sometimes several times in a year because governments change.
- During WWII, Britain had double summer time. Yes, Greenwich was on GMT+2.
- Libya, in 2013, with a few days' notice, decided to not put their clocks back and cancel DST.
- So every Libyan computer was wrong
- West Bank: same location, Palestinan and Israeli people follow different time zones.
- In 18th century we changed from Julian to Gregorian calendar. We didn't lose 3 weeks, we just skipped from one date to the other.
- But the Russians only changed in the 20th century.
- The dates you skipped depend on your location.
- Britain: until the 16th century, New Years was on the 25th of March. March 24, 925 + 1 day = March 25, 926.
- Leap seconds. The earth doesn't move at a constant speed. Then suddenly you have 61 seconds in a minute because it goes to 23:59:59 and 23:59:60.
- UTC includes leap seconds
- Astronomical time doesn't include leap seconds so is getting out of sync