Topic: Earth’s Moon
CHARACTERISTICS
1. Origin of the Moon: the most commonly accepted __theory__ of moon formation is that a __small planet___ smashed into __earth_ about 4.5 bya and ejected earth material that _coalesced_ to form the moon.
Evidence of this include:
Moon is made of the same material as _earth’s_ mantle and crust.
It has no __volatiles__, such as water
2. The moon’s surface is ___cratered___ and many of these are billions of years old. This is because the moon lacks an __atmosphere__ which would have weathered the craters, as has happened on _Earth_
3. Moon structures:
the ____highlands__ are the light-colored, higher elevation formations and are much ____older___.
The __marias__ are the flat, dark areas that resemble ‘seas’. They are made from basalt magma flows.
4. MOON PHASES:
- The moon is ALWAYS _half_ lit by the sun.
- the moon __revolves__ around earth in 27.3 days.
- this causes different parts of the lit moon to be __visible__ to us.
5. ECLIPSES:
- An eclipse occurs when one object is in the _shadow_ of another.
- In the alignment of earth, moon and _sun__, there are two possible eclipses:
- _Lunar_ eclipse occurs when the __Earth’s__ shadow falls on the moon. It can only happen during the __full_ moon phase.
- __Solar_ eclipse occurs when the moon moves in front of the _sun__ and makes the day dark. It can only happen during the __new___ moon phase.
Draw:
6. Why don’t eclipses happen every month? The moon’s _orbit_ is at a 5 degree tilt to the earth’s orbit. Therefore, it is very rare that the little tiny _moon_ will line up perfectly for _eclipses_ to happen.
7. The moon’s phases change every __29.5 days_, which is longer than the moon’s ___revolution__ around earth. This is because the earth is moving in its orbit at the same time.
Draw:
8. The moon rises ___50 minutes__ later each night because, while the moon is revolving around the earth, the earth is __revolving_ in its own orbit.
htp://astro.unl.edu/classaction/loader.html?filename=animations/lunarcycles/moonphases.swf&movieid=moonphases&width=900&height=600&version=6.0.0
9. Ocean tides and moon phases:
The moon is close to the earth (300,000km) and the __gravitational_ pull between earth and moon is strong. The fluids on earth, _ocean_ and _air_, are pulled toward the moon. This means that the ‘_high’ tides are always pointed toward the moon and directly away from it.
10.Tides occur when the __height_ of the water at the beach or shore changes cyclically. During high tides, the water comes up the beach, and during low tides it is lower on the beach. Tides occur every 6.25 hours, and are caused by the moon.
11.__Spring_ tides occur during full and _new__ moon phases, when the pull of the moon and _sun work together. High tides are very high and low tides are very low.
Draw:
12.___Neap_ tides occur during both quarter phases, when the pull of the moon and sun work AGAINST each other. There is little change between high and low tides
13. Moon’s rotation: We always see the same side of the moon because the moon only ___rotates_ once every time it revolves. On the diagram, the arrow is the same spot on the moon in each picture.