MOON FACTS

Each year, the Moon steals some of Earth's rotational
energy, and uses it to propel itself about 3.8 centimeters
higher in its orbit. Researchers say that when it formed,
the Moon was about 14,000 miles (22,530 kilometers) from
Earth. It's now more than 280,000 miles, or 450,000
kilometers away.


The moon formed as a result of a collision known as the
Giant Impact or the Big Whack, scientists figure. It went
like this: A giant Mars-sized object hit Earth 4.6 billion
years ago shortly after the birth of the sun and the solar
system. A cloud of vaporized rock was kicked up (a mix of
Earth and the other object) and went into orbit around
Earth. The cloud cooled and condensed into a ring of small,
solid bodies, which then gathered together, forming the
moon.

                           

Long ago, the Earth's gravitational effects slowed the
moon's rotation about its axis. Once the moon's rotation
slowed enough to match its orbital period (the time it
takes the moon to go around Earth) the effect stabilized.
So the moon goes around the Earth once and spins on its
axis once, all in the same amount of time, and it shows us
just one face the whole time.


The moon is about 27 percent the size of Earth and far less
massive. Gravity on the moon is only about 1/6 of that on
Earth. If you drop a rock on the moon, it falls more slowly
(and astronauts can hope much higher). If you weigh 150
pounds on Earth, you'd weigh 25 pounds on the moon.


The moon's orbit around Earth is an oval, not a circle, so
the distance between the center of Earth and the moon's
center varies throughout each orbit. At perigee, when the
moon is closest to Earth, that distance is 225,740 miles
(363,300 kilometers). At apogee, the farthest position,
the distance is 251,970 miles (405,500 kilometers).


At full moon and new moon, the sun, Earth and moon are
lined up, producing higher than normal tides (called spring
tides, for the way they spring up). When the moon is at
first or last quarter, smaller neap tides form.