Quote:
Originally Posted by irpq11
Welcome to Camaro5 
I don't know any of this stuff. Just offering up some food for thought. 
Interesting thread for your first post. 09' Chally, sweet. |
Well, he's right and wrong, in a sense. I'll try to explain There is a very important mathematical equation that defines gravity:
F = GMm/R²
F is the Gravitational force
G is the Gravitational constant, 6.67*10^(-11) N-m²/kg².
M is the mass of object 1 (we'll say the earth)
m is the mass of object 2 (the moon)
R is the radius
between the two object's center of gravity
The last part is important. Notice the equation says nothing about volume, or density. All that matters is mass (no pun intended :p). So, regardless of the earth's size, assuming it had the same mass, the moon would revolve around it at relatively the same distance. Whether the earth was the size of a basketball, or the size it is now. (granted if it was the former, it would probably end up as a black hole!)
Now, whats really interesting about the moon in this theory is its creation. Its believed that the moon was created from a very early collision between the earth and a meteor. A chunk of molten earth was blasted off in to space, and slowly coagulated into our modern day moon.
To do this, the meteor was pretty big in relation to the Earth, something like 1/4 the size of present day Earth. If earth had been much smaller, the metor would have had a much larger effect on our planet.
Also, why isn't the moon expanding?