To be turbo pedantic, Russia adopted a different calendar in 1918.
Gregorian and Russian calendars will diverge in 4000 CE.
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<https://www.mindthegapdialogs.com/home>
On Mon, Jul 15, 2024 at 10:00 AM Paul Winalski <paul.winalski(a)gmail.com>
wrote:
On Sun, Jul 14, 2024 at 5:25 PM Marc Donner
<marc.donner(a)gmail.com>
wrote:
Note that the switch to the Gregorian calendar
happened at different
times in different countries. In Catholic-dominated countries it happened
in October of 1582. The English-speaking world, being
Protestant-dominated, waited until September of 1752 to adopt it.
And Russia didn't adopt the Gregorian calendar until 1918. IIRC the
Eastern
Orthodox churches still use the Julian calendar for scheduling
ecclesiastical events such as the date of Easter.
-Paul W.