What keeps the Moon in its place?
What’s the orbital speed of the Moon?
The Moon stays in its stable orbit by virtue of
equilibrium of forces of the pull of the Moon trying to
escape from us, and the pull of Earth’s gravity. If the
Moon were moving faster it would escape Earth's
gravity. If the Moon were moving much more slowly,
gravity would pull it down to the Earth.
The Moon travels around Earth at an average speed of
2,288 miles per hour (3,683 kilometers per hour).
During one complete trip around Earth (one orbit) the
Moon travels 1,423,000 miles (2,290,000 kilometers).
Why there are so many craters on the
Moon?
Our Earth is protected by an atmosphere that
absorbs many of the thousands of meteorites
that travel randomly through space. The Moon
doesn’t have this kind of protective jacket. So
every meteorites heading to the Moon will
eventually hit its surface forming on more crater
among the thousands already existing.
Comparing the Moon with the
Earth
The Moon is about one fourth of the
Earth’s diameter. If the Earth were
hollow, it would take about 50
Moons to fill the volume of the
Earth. However, since the Earth is
denser than the Moon, it would take
about 81 and a half Moons to
balance the weight of the Earth.
Why do we always see the same
side of the Moon?
It’s a common myth that the Moon
doesn’t rotate around itself like the
Earth does. However, the Moon
rotates around itself in almost
perfect synchronization with its
rotation around the Earth.
A Moon’s day is 27 Earth’s days and
7 hours and 43.2 minutes long.
Ref. http://helios.gsfc.nasa.gov/qa_earth.html
How far away is the Moon?
The Moon’s orbit is not a perfect circle, so the Moon is at an
average distance of 238,897 miles (384,467 kilometers) from Earth;
this is about the width of 30 Earths. Because the Moon does not
orbit Earth in a perfect circle, its orbit is said to be elliptical.
Comparing the Moon with the Sun
The Sun is 400 times larger than the Moon, but the Moon is 400
times closer to the Earth than the Sun. That’s the reason why
they appear the same size when solar eclipses happen. This is a
rare coincidence that is happening at this time of the Earth’s
history. Fortunately, we are here at this moment to see this
spectacular celestial show. However, there are many planets
and many moons in the universe. So this cosmic event may be
also be happening many times elsewhere in faraway places in
our or other galaxies.
The Moon protects the life on the Earth
The Moon is orbiting the Earth in an imaginary plane –called the ecliptic--the
near the Earth’s equator. But at the same time, the equator is the region of
the Earth that receives the most sunlight, an indispensable ingredient for the
support of life. By orbiting around the equator, the Moon is continually
absorbing a great quantity of the destructive meteorites from hitting the
Earth. The great winner in this cosmic scenario is the life in the Earth.
© E. Pérez http://4DLab.info