As far as we know, the equation presenting Newton’s gravitation law still remains as an empirical equation. The nature of the force predicted and described by this law continues hiding in heavy fog in our understanding. However, some down to Earth experiment that anyone can perform appears able to provide us with highly potential key to unlock the secret of this law and its equation. The behavior shown by two objects submerged in a fluid shows high parallelism to the behavior shown by two heavenly objects under gravitational influence. This similarity leads to an inference that all heavenly objects in the universe are submerged in a fluid. Calculation led by the gravitational data reveals to us that this fluid has insanely high intrinsic pressure. Then, it is this high pressure that makes the gravitational "attractive" force inevitable. Indeed, more accurately, gravitational attractive force should be called gravitational pushing force. As such, gravitational force existing between all heavenly objects becomes the evidence of a fluid that is omnipresent. This fluid is called Aether in this article. Of course, as it is omnipresent, light must interact with this fluid everywhere. Its frequency-shift interaction with light is confirmed by Ives-Stilwell experiment. Then, Ives-Stilwell experiment becomes the second evidence of the existence of this fluid. We will discuss the second evidence in another article.