5/5 Elena S. 1 year ago on Google
Prime
Meridian
has
a
fascinating
history
on
its
own,
definitely
worth
being
taken
in
consideration.
The
Greenwich
Meridian
is
used
to
separate
east
from
west
in
the
same
way
that
the
Equator
separates
north
from
the
south.
In
1884
in
Washington
D.C.
delegates
gathered
for
an
international
convention
to
determine
where
the
0°
of
longitude
should
be.
The
majority
of
shipping
companies
at
that
time
were
already
using
British
charts
based
on
the
British
Meridian
and
it
seemed
agreeable
for
most
of
the
nations
represented
to
move
towards
a
decision
of
adopting
the
same
one
as
a
Prime
Meridian
(longitude
zero).
The
delegates
recommended
also
the
definition
of
a
new
global
time
zone
system
based
on
the
Greenwich
meridian.
The
alignments
were
checked
with
the
help
of
two
telescopes
used
together
to
determine
the
collimation
(sight-line)
of
the
Airy
Transit
Circle’s
telescope
and
to
ensure
it
is
aligned
correctly
on
the
Meridian.
In
a
separate
building
there
is
a
huge
telescope
that
defines
the
Prime
Meridian
even
today.
The
telescope
was
commissioned
by
George
Biddell
Airy,
seventh
Astronomer
Royal.
History
tells
us
that
Astronomers
worked
in
pairs
on
the
Airy
Transit
Circle:
one
looked
through
the
eyepiece
while
the
other
observed
the
microscope
readings
on
the
stone
pier.
The
other
two
astronomers
that
worked
on
the
meridian
line
were
Edmond
Halley
and
James
Bradley.
Halley’s
Meridian
line
was
defined
by
measuring
the
height
of
stars
above
the
horizon;
then
their
passage
(or
‘transit’)
was
timed
over
the
meridian
mark
by
crosshairs
in
his
telescope
with
an
accurate
pendulum
clock.
One
of
the
most
important
observations
was
the
Sun
at
solar
noon.
Bradley’s
Meridian
line
was
defined
by
the
third
Astronomer
Royal
who
observed
with
improved
accuracy
while
using
the
telescope.
Time
was
measured
by
using
distant
stars
⭐️
in
an
attempt
to
be
more
accurate
having
in
mind
the
unequal
length
of
solar
days.
It
is
said
that
Astronomers’
clocks
run
slightly
faster
than
normal
clocks
to
show
sidereal
(star)
time.
Time
has
already
began
to
play
an
important
role
with
timekeeping
and
clocks
being
introduced
in
homes
🏡
and
trades.