Started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors.
Answer: Metamorphism occurs under the influence of extreme heat, pressure, and/or chemical fluids. A rock undergoing metamorphism changes the texture and mineral composition of the rock but never leaves solid form. If the rock were to melt and be changed that would classify it as an Igneous rock.
It is commonly known that our Galaxy rotates upon the sun because of gravity. The diagrams' arrows sort of describe it. Id suggest Gravity as the answer.
