Final answer:
Leland Stanford, a business tycoon and racehorse owner, hired Eadweard Muybridge who used innovative photographic techniques to prove that a horse's legs can all leave the ground during a gallop, in a series of photographs called The Horse in Motion.
Step-by-step explanation:
The individual who bet $25,000 to prove that a horse's legs come off the ground during a gallop, dramatically changing the way we perceive movement, was Leland Stanford. A tycoon and racehorse owner, Stanford hired photographer Eadweard Muybridge for this purpose.
In 1878, through a series of photographs titled The Horse in Motion, Muybridge utilized advanced photographic techniques and equipment to capture a horse named Sallie Gardner at a gallop, proving that all four legs do indeed leave the ground simultaneously. Prepared glass plates and the reduction in exposure time to 1/25th of a second were key to capturing these movement sequences.
The works of Muybridge, like Galloping Horse, are monumental in both art and science, as they provided objective evidence that supported scientific studies in human and animal locomotion. His photographic methods, capable of nearly instantaneous exposure, paved the way for the development of motion pictures and became a cornerstone of visual experiments in the study of movement.