lithosphere or geosphere
lithosphere
The zenith.
A sphere.
Cryosphere
At the equinoxes, the Sun is directly over a spot on the equator.
Gravity. Gravity pulls things together equally in all directions. This means that once the amount of material collected together gets big enough to it flows into a sphere. However, if the sphere is rotating then the speed of the spin want to fling material out and this means that spinning bodies are not spheres but 'oblate spheroids', they are fatter round their middles.
sediment sphere
The mass of a sphere is 4/3*pi*r3*d where r is the radius of the sphere and d is the density of the material of the sphere.
west
The zenith.
A sphere.
That's called the observer's "zenith".
Cryosphere
i guess i guess i guess i guess
sphere of influence
Guy golly Depending on the size, either gravity or magnetism.
If the charge is evenly distributed over the sphere ... as it would be if the sphere is a conducting material ... then the electric field at the center of the sphere is zero. If the sphere is not a conductor and the charge hasn't been applied to it symmetrically, then the magnitude and direction of the electric field at the center depend on every little detail of exactly how it's distributed on the sphere.
The sphere made from the least dense material. If this is for a specific math problem, you may have to calculate density by dividing mass / volume for each sphere. The question could be about the "four spheres of the Earth" : Atmosphere Biosphere Hydrosphere Lithosphere. In that case the answer is the "atmosphere".