General properties and motion of moon.

1. Moon: Its General
Properties and Motion

2. Moon
- It is the Earth’s only natural satellite.
- It is the second densest satellite among
those densities are known.
- It is the second brightest regularly visible
celestial object in the Earth’s sky.
- It was formed 4.5 billion years ago from the
debris left over from an indirect collision
between the Earth and an astronomical
body the size of Mars.

3. General properties
of the Moon
 Size
The diameter of the moon is 3479 km
(2162 mi). This about ¼ of the Earth’s
diameter.
 Mass
The mass of the moon is 7.35x 10²² kg,
which is about ⅛ of the Earth’s mass.
 Density
The moon’s density is 3340 kg/m³ or
3.3x10⁴ g/cm³.

4.  Reflection
The moon’s average visual albedo is
12%, the brightness of the moon changes
dramatically as its phases changes. During
first and third quarter, the visible moon is
50% illuminated by the sun, but its
brightness is only about 8% of the full moon.

5.  Distance
Its current distance is about 30 times
the diameter of the Earth, causing it to
have an apparent size in the sky almost
the same as that of the sun. This allows
the moon to cover the sun nearly
precisely in total solar eclipse.

6.  Age
The moon is thought to have formed nearly
4.5 billion years ago from the debris left over
after the collision between Earth and the Mars
sized body.
 Temperature
The average temperature on the surface of
the moon during the day is 107°C. That is hot
enough to boil water on Earth. During the night,
the temperature drops to ¯153°C.

7.  Gravity
Because of its smaller size and mass, the
gravity of the moon is about ⅙ the gravity of the
Earth, that means that a person who weighs
180 lbs on Earth would only weigh 30 lbs, if
measured on the moon.
 Moon Causes Tides
The force of gravity from the moon affects
the Earth. Its gravity reaches the Earth and pulls
the ocean towards the moon, causing tides. The
highest tides will occur when the moon and sun
are aligned and that is when there is New Moon
or a Full moon.

8. Motion of the Earth’s Moon

9. - the motion of the moon is always synchronous
to the Earth.
- The moon moves 13.2° per day relative to the
stars which is just over half a degree per hour
and approximately equal to its apparent size.

10. In order to be seen again in the same
phase, i.e., in order to return in the same
position with respect to the stars, the moon
has to turn a little bit more than just one lap
around the Earth, while 29 days, 12 hours,
and 44 minutes need to go by between two
New Moons. This period of the time is called
“Synocdic Month” or “Lunation.

11. Motion of the Moon:
Rotation of the Moon on its
Axis: