To understand how astrology works, we
should first take a quick look at the sky. Although the stars are at enormous
distances, they do indeed give the impression of being affixed to the inner
surface of a great hollow sphere surrounding the earth. Ancient people, in fact,
literally believed in the existence of such a celestial sphere. As the earth
spins on its axis, the celestial sphere appears to turn about us each day,
pivoting at points on a line with the earth’s axis of rotation. This daily
turning of the sphere carries the stars around the sky, causing most of them to
rise and set, but they, and constellations they define, maintain fixed patterns
on the sphere, just as the continent of Australia maintains its shape on a
spinning globe of the earth. Thus the stars were called fixed stars.
The motion of the sun along the ecliptic is, of course, merely a
reflection of the revolution of the earth around the sun, but the ancients
believed the earth was fixed and the sun had an independent motion of its own,
eastward among the stars. The glare of sunlight hides the stars in daytime, but
the ancients were aware that the stars were up there even at night, and the slow
eastward motion of the sun around the sky, at the rate of about thirty degrees
each month, caused different stars to be visible at night at different times of
the year.
The moon, revolving around the earth each month, also
has an independent motion in the sky. The moon, however changes it position
relatively rapidly. Although it appears to rise and Set each day, as does nearly
everything else in the sky, we can see the moon changing position during as
short an interval as an hour or so. The moon’s path around the earth lies nearly
in the same plane as the earth’s path around the sun, so the moon is never seen
very far from the ecliptic in the sky. There are five other objects visible to
the naked eye that also appear to move in respect to the fixed background of
stars on the celestial sphere. These are the planets Mercury, Venus, Mars,
Jupiter, and Saturn. All of them revolve around the sun in nearly the same plane
as the earth does. So they, like the moon, always appear near the ecliptic.
Because we see the planets from the moving earth, however, they behave in a
complicated way, with their apparent motions on the celestial sphere reflecting
both their own independent motions around the sun and our motion as
well. |
