xkcd.flow

(Did you know that,
 [(the, [Fall|Spring], equinox)
  |(the, [Winter|Summer], [solstice|Olympics])
  |(the, [earliest|latest], [sunrise|sunset])
  |(daylight, [saving|savings], time)
  |(leap, [day|year])
  |Easter
  |(the, [harvest|super|blood], moon)
  |Toyota Truck Month
  |Shark Week],
 [(happens, [earlier|later|at the wrong time], every year)
  |(drifts out of sync with the,
    [sun|moon|Zodiac
     |([Gregorian|Mayan|Lunar|iPhone], Calendar)
     |atomic clock in Colorado])
  |(might, [not happen|happen twice], this year)],
 because of,
 [(time zone legislation in, [Indiana|Arizona|Russia])
  |a decree by the Pope in the 1500s
  |([precession|libration|nutation|libation|eccentricit|obliquity],
    of the,
    [moon|sun|earth's axis|equator|prime meridian|
     ([International Date|Mason-Dixon], Line)])
  |magnetic field reversal
  |(an arbitrary decision by, [Benjamin Franklin|Isaac Newton|FDR])],
 ?,
 Apparently,
 [it causes a predictable increase in car accidents
  |that's why we have leap seconds
  |scientists are really worried
  |(it was even more extreme during the,
    [bronze age|ice age|Cretaceous|1990s])
  |(there's a proposal to fix it\, but it,
    [will never happen
     |actually makes things worse
     |is stalled in Congress
     |might be unconstitutional])
  |it's getting worse and no one knows why],
  .)