Bad Astronomy: Misconceptions and Misuses Revealed, from ...

130 SKIES AT NIGHT ARE BIG AND BRIGHT
at any moment one side of the Earth is nearer the Moon than the
other. The side nearer the Moon therefore feels a slightly higher
gravitational force from the Moon. This acts to stretch the Earth a
tiny amount. We see this effect as a raising and a lowering of the
sea level twice a day, which is what most people normally think of
as tides.
Earthquakes are caused by the movement of huge tectonic plates
that make up the Earth’s crust. They rub against each other, usually
smoothly. However, sometimes they stick a bit, letting pressure
build up. When enough pressure builds up, the plates slip suddenly,
causing an earthquake. Since tides can stretch an object, it’s
reasonable to ask whether tides can trigger earthquakes. Are we
still doomed?
Happily, no. When doomsayers bring up tides, they are shooting
themselves in the foot. The force of tides fades even faster with
distance than gravity. If the force of gravity on Earth is piddly for
the planets, then tides are even weaker. Comparing the Moon,
again, to all the combined might of the planets, we find that the
Moon has 20,000 times the tidal force of all the other planets
in the solar system, even at their closest approach to the Earth.
Remember, in May 2000 the planets were as far away as they possibly
could be. The tidal force was so small that even the finest scientific
instruments on the planet were not able to measure it.
Round 2 of the fight goes to science as well.
Math and science show pretty definitively that the gravity and
tides of the planets are too small to have any effect on the Earth.
However, it would be foolhardy to assume that emotions are swayed
by logic. In one sense, the side of science is lucky: since the planets
were all on the far side of the Sun, we had to look past the Sun to
see them. That means they were only up during the day, when they
are practically invisible. It would not have helped the situation if
people could actually look up at night and see the planets approaching
each other, even if it were a pretty weak grouping.
Still, even armed with hard numbers, it’s always an uphill fight
to battle the doomsayers. There were a lot of people out there trying
to make money by scaring people about the alignment. Certainly
some of these folks were honest, if misguided. Richard Noone