The prevailing theory regarding the origin of the Moon suggests that it was formed around 4.5 billion years ago as a result of a collision between Earth and a Mars-sized protoplanet called Theia. The impact caused debris to be ejected into orbit around the Earth, eventually coalescing to form the Moon. This theory is supported by the composition of Earth’s mantle and lunar rocks. However, a recent study conducted by Stephen Lepp and his team from the University of Nevada has shed new light on this long-held belief.
After the formation of the Moon, it initially orbited Earth at a distance approximately 5% of its current value. Over time, due to tidal effects between Earth and the Moon, the Moon drifted away to its current altitude. The surface of the Moon was initially covered in molten magma, which gradually cooled and solidified to form the crust, mantle, and core we see today. The lunar surface bears the scars of heavy bombardment, with impact basins and craters dotting the landscape. Volcanic activity also played a role in the formation of the lunar maria.
The orbit of the Moon around Earth is slightly elliptical, with an eccentricity of 0.0549. This deviation from a perfect circle causes the Moon to vary in distance from Earth, ranging from 364,397 km to 406,731 km. In the early days of the Earth-Moon system, the orbits of particles in the debris cloud were more erratic. Nodal precession, which describes the slow movement of orbital intersections, played a significant role in the evolution of these orbits.
Unstable Orbits and Polar Orbiting Material
The team’s research revealed that polar orbits were the most stable among all possible orbits of particles in the debris cloud during the formation of the Moon. As the Earth and Moon gradually drifted apart, the space where polar orbits could exist decreased. Today, with the Moon at its current distance from Earth, stable polar orbits no longer exist due to the dominant nodal precession driven by the Sun. The presence of polar orbiting material can drive the eccentricity growth of a binary system like the Earth and Moon.
The study conducted by Stephen Lepp and his team challenges our previous understanding of the Moon’s evolution. By examining the dynamics of the material ejected during the Moon’s formation and the stability of orbits in the Earth-Moon system, they have proposed a new perspective on how the Moon came to be. This research opens up new avenues for further exploration and may lead to a deeper understanding of the celestial bodies that shape our universe.
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