7.4.1: Could astrology work by gravity?
Description
This article is from the Scientific Skepticism FAQ, by Paul Johnson Paul@treetop.demon.co.uk with numerous contributions by others.
7.4.1: Could astrology work by gravity?
Some people argue that we are affected by the gravity of the planets
(just as tides are caused by the gravity of the Moon and Sun), and
that this is the connection between the motion of the planets and
mundane events on Earth.
Leaving aside the fact that astrology doesn't work (see above),
gravity is simply too weak to do this. Gravitational force on a mass
(such as a human being) decreases with the square of the distance to
the other mass. But the Earth is affected just as strongly by the
other mass, and accelerates slightly towards it. So the net effect on
us is nil. What is important is the difference in gravity between the
two sides of the mass. This decreases with the *third* power of the
distance (i.e. very fast) but increases with the distance between the
near and far sides. Hence the Moon and Sun cause tides because the
Earth is very large. But the difference in gravity between one end of
a human and the other is absolutely minuscule.
Also, if this were the mechanism behind astrology then the most
significant thing in astrology would be the position of the Moon, with
the time of day coming second (as it is for tides). The position of
the planets would be completely irrelevant because they are so much
further away than the Moon and so much smaller than the Sun.
Continue to:
My Books
