By having mass (matter) it will have gravity.
The short answer is "matter". From observations of objects, the more matter an object contains, the greater the gravitational force it exerts on objects around it. That theory coincides with...
They are similar, in that one is the absence of the other. However, they are not opposites, so they could not be considered 'alike'.
The gravity on earth is 9.8m/s^2 I believe the gravity on the moon is 1.6m/s^2
Depends on the atmosphere. location, place, space and time of zero gravity