The sun also raises tides on the earth. In fact,
the solar induced tide is about 40% of the
total. The moon is the other player. There
really is no life force involved; basically we can
understand how tides get raised by considering two
bodies. Let us say the earth and the moon in
isolation. Now when these bodies are very, very
far away, we can condor that the mass of earth is
acting like a point mass at the center and the
same for the moon. In this case the tidal force is
very small.....basically negligible. Now imaging
the situation when we move the moon closer to the
earth. Note now that one side of Earth is
significantly closer to the center of the moon
compared to the point on the other side of the
earth. The tidal force is actually the
DIFFERENCE in the force exerted between the sub
lunar point and the point across the diameter of
That is what the tidal force is... it is a
differential gravitational force.
ANYTHING with mass (and thus gravity) causes
tides. You cause tides with the mass from your
The moon exerts the strongest tide-inducing
force on the earth because it is relatively
massive and relatively close-by, and the strength
of tidal forces caused by an object increases with
the mass of the object and even faster with the
closeness of the object. The sun is also
important in causing tides, although not as
much as the moon because the sun is so much
farther away than the moon, even though it is much
All of the living things on Earth together add
up to a tiny amount of mass in comparison to the
mass of the earth itself. This means that while,
technically, the bodies of living things exert
tidal forces just like everything else, these
forces are so small that they are completely
overwhelmed by the mass of nonliving objects, such
as the moon, Sun, Jupiter, etc.
The Sun also affects the tides on Earth.
Both the Moon and Sun have a gravitational
force that "pulls" on the Earth. This
"pulling" force causes the Earth's oceans to bulge
on one side or another, forming the tides.
When we see a "new" or a "full" Moon, the
gravitational force from the Sun adds to the force
from the Moon, producing our largest tidal ranges
called Spring Tides. During a "quarter"
Moon, the gravitational force from the Sun
subtracts from the force from the Moon, producing
small tidal ranges called Neap Tides.
Waves, however, are not related to tides and,
instead, are caused by other things on Earth. For
example, when wind blows across the ocean surface,
waves can form. If the wind blows faster, the
waves become larger. Extremely large waves can be
made by a landslide that drops into the ocean or
by an earthquake that occurs near the bottom of
the sea. These extremely large waves are called
tsunami. Large mammals, like whales, can
make large splashes in the ocean, but these
splashes are never big enough to become tsunami.
Tsunami are not related to tides either.
The only things that can create tides are
big objects in space: moons, planets, and
stars. No life forms are big enough to
generate gravitational forces that "pull" on the
ocean to make tides.
Click Here to return to the search form.