It should be agreed that all objects like planets, stars etc. float in the full vacuum universe. It should also be agreed that atmosphere possessed by these objects is due to gravity and the atmosphere is in the open system full vacuum universe. Here, air molecules always try to escape in full vacuum universe against gravity to have uniformity in the universe. Means it is balanced between gravity and full vacuum universe. It is in science textbooks that the Earth’s atmosphere exerts pressure. But, to have pressure in the system, it must be isolated by boundary and its value is same at any point within. Here, Earth’s atmospheric air neither uniformly distributed nor in a closed system. It is known that gravity is holding each air molecule towards the Earth. On surface, air has high-density molecules and as further go away molecules density decreases. This density difference is balanced between gravity and full vacuum universe. This paper uncovers the misconception regarding Earth’s atmosphere exerts pressure due to its air molecules vertical column mass. To prove the argument, the manometer experiment is visited. In this experiment author makes the effort to raise mercury filled tube up against gravity above pot level then inverts it. Here, mercury level drops because of gravity which creates a vacuum in the top of the tube. This causes reduced surface energy inside wall of the tube. To be in the equilibrium state with outer tube wall, inner wall surface tries to suck in all direction that holds mercury up against gravity that means tube mercury weight is balanced by vacuum and that is demonstrated.