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What
is Galactic time? What
is Galactic Time? We
measure time on our planet earth to organize our society.
For
agriculture and other seasonal interests we have the
timing
to the sun
of our solar calendar: it describes what is called the
Tropical Year. This timing is respected worldwide for the
purpose of the civil calendar called the Gregorian
Calendar. It was introduced in1582 as a reform to the
Julian calendar of 45 B.C. that had run out of the
seasons with 10 days. Next to that we also have timed our
lives with sundials and waterclocks to the sun for
thousands of years. This was abolished end of the
eighteenth century when officially for pragmatical
reasons mean (mechanical) time was introduced definitely
estranging man from the ancient natural rhythm of cyclic
time. But still the passage of the sun over the Greenwich
meridian is the standard scientific reference of
world-time (UTC) for modern timekeeping however twisted
by modern time politics. (see
articles) In
China, India and other eastern cultures one times one's
month's and weeks to
the moon
in a lunisolar way: one respects the rhythm of the
moon, but intercalates a month so now and then on that
lunar calendar to keep track with the seasons: a leaped
calendar. Because this can be done several ways the
Romans for the West abolished this method with the
Jullian reform seeing it leading to arbitrariness and
corruption. The Islam for religious purposes manages a
purely lunar calendar which is not leaped but is counting
twelve lunar month's as a lunar (culturally conceived)
year about 11 days shorter than the solar year.
(see
calendar-links) Apart
from our spinning moon which gives us lunar time and our
spinning to the sun which gives us solar time, we also
have timing
to the stars. This
timing is called sidereal time and is mainly used for
purposes of astronomical observation and has little or no
social relevance. This concept of time makes no real
calendar, although it sets apart another
sidereal zodiac from the seasonal one astrologers
use.
The siderical year describes days shorter with four
minutes and a year one day longer because a sidereal day
is defined as the time it takes to see the stars in the
same position in the sky: 23 hr. and 56
minutes. Galactic
Time is
the time that is described by our spin relative
to
the center of the galaxy. Just
like the moon spinning around the earth and the earth
spinning around the sun, we all together, sun moon and
earth and the other planets are spinning around the
center of our galaxy, the Milky Way. The
animation to the left shows how in a time of six years
the stars in the center of the Galaxy are spinning around
the center. The center is situated in Sagittarius A, and
is possibly
a young black hole
: a
mass of two million times that of the
Sun.
A galactic
day
can thus be understood as one revolution around the sun
of the earth relative to the center of the galaxy. It
gives a slightly longer (about 1/71 day) 'galactic' year
(in fact a galactic day thus) that runs through the
seasons beginning when we are closest to the center of
the galaxy (or at the greatest distance, there is no
cultural precedent). This slightly longer year is due to
the precession
of the
equinox
causing
the date of the galactic new
Day
to
move upward through the calendar ( see also the
Hutchinson
Encyclopedia).
A galactic
year
can
be described as one revolution around the center of the
galaxy which at a speed of about 250 km/sec. takes
about
226 millions of years with a radius of about 26 thousand
lightyears.
The age of our solar system is about 20 of these
revolutions. Thus we are 20 galactic years old departing
from the supposition that our galaxy the Milky Way, is
about 4.5 billion years old. |next © The
Order of Time
Deze
pagina in 't Nederlands
The
galaxy centre by the telescope from Cerro Tololo, Chile