PARALLAX:
Parallax arises
from the different points from which which
two observers view an object. A simple example
of
parallax
in our everyday lives provides an easy way to
understand what parallax is.
An
example of parallax is this: Two people
are standing 30 feet apart and are looking at
the same object
50 feet away. When each of the two people points
to the object, an imaginary line drawn from person
A to the object and an imaginary line drawn from
person B to the
object are not parallel. The object is in a different
place relative to the background.
Measuring
parallax: The
closer the object is relative to the distance between
the people, the greater is
the angle of the two yellow lines in the diagram
where they meet at the object being viewed. This
angle is a measure of parallax. As the object is
moved farther away, parallax decreases and at an
infinite distance becomes zero. Note, however,
that size of parallax depends on two things: the
distance by which the two observers are separated
and the distance of the object being viewed. Note
that given the distance between two people and the
angle of parallax, the distance of the object can
be determiend so parallax can be used to determine
the distance of an object. To do this, we need two
points of viewing the object and a background to
reference where the object is from these two points
of view.
There are two basic kinds of parallax in
astronomy that are relevant to astrology, and I describe
them below:
- Stellar
Parallax: Astrologers
often tend to think of fixed stars as
having a given position in a particular
year.
In the
tropical zodiac
the only motion of the fixed stars that we usually
consider in astrology is the precession of the
fixed star forward in the tropical zodiac by
an amount of 1 degree in approximately 72 years.
However, stars also have a motion of their own,
known as their proper motion, but the proper
motion of a star is very slow. Proper motion
is not completely negligible, however. The star
with the fastest proper motion is Barnard's star
and it moves more than 1 minute of arc
every 6 years. This 1 minute of arc, however,
is its
direct motion and measured along any given celestial
plane is likely to be less than this. However,
our topic in this article is parallax and not
proper motion. As the Earth revolves around the
Sun, the fixed stars are being viewed
from the Earth at a different point in
space. However, the fixed stars are so
far away, that this parallax results
in a difference of less than 1 second
of arc in the position of the fixed star!
This very small amount can be disregarded
for astrological purposes, so stellar
parallax is not of great importance to
astrologers.
- Lunar
Parallax: If
I look at the Moon right now where I
am in Florida and
someone half way around the world
looks at the Moon (assuming the Moon is
above the horizon so you physically
see it but even if not physically
observable because below the horizon the
same principle applies),
the Moon is seen as being
about 2 degrees
different in
its zodiac position by
the two of us. Even though
the circumference of the
Earth may not seem great
on a celestial scale, it
is significant in relationship
to viewing the Moon because
the Moon is relatively very
close to Earth as compared
to other celestial objects. The
Moon position normally used
in astrology is based on where the Moon is from
the point of view of the center of the Earth,
and is therefore a "compromise" position so
that the maximum difference
of the parallax-corrected
Moon position from the usual
position that astrologers
use is about one degree. You can approximate
lunar parallax by measuring the angle of the Moon
from the MC-IC axis. When
the Moon is conjunct the MC or IC parallax is near
zero. When the Moon is square the MC and the Moon
is on the east side, i.e. near the Ascendant, then
the parallax-corrected Moon approaches about one
degree ahead of the usual Moon position. When the
Moon is square the MC and the Moon is on the west
side, i.e. near the Descendant, then the parallax-corrected
Moon approaches about one degree behind the usual
Moon position. The parallax-corrected Moon is therefore,
you might say, "lowered" in the chart wheel.
You can also calculate parallax-corrected positions
of the Sun and the planets, but the difference between
the parallax-corrected positions and the usual positions
is very small (less than one minute of arc).
Parallax
is a big issue. It is possible that
astrologers are using an
incorrect position of the Moon by not using the
parallax-corrected Moon position. In
research that I have done in the past amazingly
the parallax-corrected
Moon
seemed
to not work as well as the plain old
Moon and this surprised me. I suspected
that the parallax-corrected Moon would
be more accurate because it is the
position of the Moon from the person's
point of view. In a birth chart it
is where the Moon is if one looks up
at the night sky. The research that
I have done or that anyone else has
done up to this point in time is not
definitive. There are no research studies
that clearly and unambiguously support
astrological theories, so we are still
at a stage of building models, gathering
anecdotal evidence, and doing exploratory
research.
The parallax-corrected Moon affects
everything that an astrologer may interpret:
the birth chart, forecasts, AstroMaps, etc. The parallax-corrected
Moon is simply at a different position than the usual
Moon, and, as noted above, is up to about one degree
different in its placement.
The elevation of a place from sea level
also has an effect on parallax. At
the top of a mountain parallax is greater than at sea
level. The difference in elevation
can change the parallax-corrected position of the Moon
by up to a few minutes of arc.
Note
that there are other important issues that are
also regarded as unimportant by astrologers, such as
refraction of light and the speed of light, for example.
These topics can be addressed in a separate article in
the future. |