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Even if it were to be taken seriously, World Jump Day's claim was completely unscientific and was widely discredited[5][6]. There are a number of reasons to reject the thesis:

* It is impossible to permanently change the Earth's orbit using the planet's own mass (which includes that of the world's population) unless such mass is ejected from the Earth at escape velocity (see Newton's third law of motion). The center of gravity of the system containing the earth and its population of humans will remain in the exact same orbit it was always in throughout the jump. However, for the very brief moment when the jumpers were in the air, the Earth's orbit would have been moved a tiny bit - only to be restored to its exact same location by the force of gravity acting between the jumpers and the planet while they were in the air.

* Even ejecting such mass from the Earth (or colliding to it from outer space), the resulting energy would be equivalent to only 2% of the energy released by a modern hydrogen bomb, shifting the Earth's orbit just a small fraction of the radius of a single atom [7].

* Since the Earth's orbit is elliptic, there are already great variations in its distance from the Sun (about 5,000,000 km) with no generally noticeable changes in temperature. Applying a brief force to the surface of the earth would not move its orbit further from the sun - it would merely change the shape of the ellipse - so at some times of year the earth would actually be closer to the sun whilst at others it would be further away.
--wikipedia