Answer 2:
Good question! The moon orbits (travels around)
the earth because of the inertia of the moon and
the gravitational force between the earth and the
moon. So what does that mean? The inertia of an
object means that it will tend to continue to move
in the same direction at the same speed unless a
force “pushes” or “pulls” it. The gravitational
force between the earth and the moon “pulls” the
moon toward the earth, and this pull is balanced
by inertia, so the moon doesn’t fall into the
earth. The moon’s inertia would cause it to go
flying off into space in a straight line if there
weren’t anything pulling on it. If the earth were
to disappear, there would be no strong
gravitational “pull” on the moon, and it would go
flying off into space in a straight line. The moon
would not continue in its circular orbit without a
planet or other object “pulling”. I included a
picture that shows what would happen.
moon around earth
Imagine that you have a tennis ball tied to a
string and you are swinging it around above your
head. In this example, your hand is the earth and
the tennis ball is the moon that is orbiting
around your hand. The ball is attached to your
hand by the string so it can’t fly off. The
tension in the string is like gravity. You can
feel the tennis ball tugging on the string– that
is because it has inertia and wants to travel in a
straight line. If you cut the string (making the
“gravity” disappear) the ball would go flying off.
All massive objects in our solar system and the
universe have gravitational forces between them.
That means that even if earth disappeared, the
moon would still be “pulled” by other things. The
moon would eventually (maybe after a very long
time) get “caught” by the gravity of another
object and start to orbit it (circle around it).
That object may be another planet, but it is very
difficult to predict which planet it would be. I
suppose that would depend on what direction the
moon was traveling when the earth disappeared and
it went flying off. Remember that the objects in
our solar system also orbit around the sun. The
moon is orbiting earth, but both are orbiting the
sun.
The moon has been around for 4.5 billion years.
The moon will still be around long after we are
gone.
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