Quote:
Originally Posted by Tropo-Bob
Is the New Year marked by Sirius being at its 'Noon' position at midnight. Is this just a coincidence or does the New Year actually commence with the brightest star being in its highest position at midnight?
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Hi Bob,
Happy New Year.
The short answer is that the position of Sirius plays no part in the marking
of the New Year on the Gregorian Calendar.
Historically, various cultures have tended to use calendars based on either
solar cycles, lunar cycles or a combination of both.
In the West, calendars with their roots based on solar cycles have been the
predominant type in use for the last couple of thousand years.
What is known as the Tropical Year is the time it takes the Sun, as viewed
from the Earth, to return to the same point, for example from one
vernal equinox to the next.
The calendar that most of the world uses today is the Gregorian Calendar,
named after Pope Gregory XIII, which in turn was a tweaked revision of
the Julian Calendar, which was introduced by Julius Caesar in 46BC.
The design of the Julian calendar attempted to try and make a year close
to a Tropical Year.
When it was introduced, one of the reforms of the Julian Calendar was
an attempt to realign January 1 with a Tropical Year and to do this
they made the year 46BC 445 days along.
Even though they knew a Tropical Year was around 365.25 days and
even though the Julian Calendar has the concept of adding additional
days now and then to try and compensate - analogous to leap days -
they came about by decree rather than being always automatically taking
place.
Fast forward to 1582 and the Julian Calendar had got out of whack
with the Tropical Year to so much of an extent that it bothered the
Vatican.
They wanted Easter to take place close to the northern spring equinox
and they codified the insertion of leap years that we use today in what is
known as the Gregorian Calendar. Thus over time, Grergorian Calendar
days of the year no longer corresponded
with particular Julian Calendar days of the year.
In England, the Gregorian Calendar wasn't adopted until 1752.
There was what was known as the Calendar Act 1750 and to
bring the calendar inline two weeks were removed from the
month of September 1752. In England, between 1155 and 1762,
legally March 25th, what was known as Lady Day, marked the start of
the year but the Calendar Act made January 1 the start of the
year for legal purposes.
These days our time system is based on atomic clocks and the Gregorian
Calendar.
However, you can appreciate that owing to the various reforms to the
calendar over the last couple of thousand years and given the Earth's
precessional and nutational wobble that changes the apparent position
of the stars from year to year and given the stars apparent motion
since they are drifting through the galaxy, Sirius doesn't have anything
to do with timekeeping of calendars in use.
.
