Fermi Effect and the Moon

To recap:
The latest Hubble Deep Field picture: http://hubblesite.org/newscenter/archive/releases/1996/01
shows a close view of one tiny spot of sky where there seemed to be nothing.
It is filled with galaxies, and each galaxy has billions of stars. Somewhere there should be some life like us. There is an equation describing the likelihood of life outside Earth, the Drake equation:
http://en.wikipedia.org/wiki/Drake_Equation
It just takes all the fractions involved and puts them together. The chance of there being intelligent life out there is the fraction of stars with planets times the fraction of those planets with life times the fraction of those planets with inteleigent life.
So Fermi's question was simply, "So where are they?"
There are several possibilities.

1. They are here. UFO's are real aliens.
2. They are not here, because travel across space is impractical and not worth the trip. What could we have worth traveling on a trip so long it would take a generation between star systems?
3. They are not here because we are the first.
4. They are not here because they just are not interested in us.
5. They are not here because natural disasters always destroy them before they become able to travel this far.
6. They are not here because technological disasters always destroy them before they become able to travel this far.

Another factor needs to be added to the Drake equation: our moon. Scientists believe our moon was created when the Earth was young, about 4.6 billion years ago, by the impact of a mars-sized object. Since then the interaction of the two has slowed the day on Earth, as well as the moon, whose day is no the same as its "year", the time it takes to go around the Earth. That is why it always keeps the same side towards the earth. Because of the angle of its orbit, it stabilizes the axis of the earth at about 23 degrees, giving us seasons. These factors make life easier on Earth.
Simple explanation:
http://burro.cwru.edu/Academics/Astr221/SolarSys/earthmoon.html
Complete explanation:
http://en.wikipedia.org/wiki/Tidal_acceleration