The most popular theory regarding lunar formation is that a Mars-sized planetoid slammed into the Earth and flung molten debris into orbit around 40 million years after the solar system was created, according to scientists at the National Aeronautics and Space Administration (NASA). This is called the giant impact theory.Know More
Debris from the collision was bound together by gravity, and these ejected particles coalesced to form the moon. Initially, both the Earth and moon spun very fast on their axes, but they have since slowed down. The giant impact hypothesis explains why the moon is made of lighter elements without a heavy core. This mathematical model also explains why the moon's orbit became tidally locked with the same face towards the Earth at all times.
There are two other theories regarding how the Earth's moon formed. One is that the moon was created at the same time as the Earth because particles were coming together during the solar system's formation. If this is true, then scientists believe the moon would be much denser.
Another theory of lunar formation involves the Earth's gravity capturing a moon passing by the planet. This is how Mars got its two moons. Scientists think that if this how the moon came into Earth's orbit, the celestial body wouldn't be spherical nor would the moon line up with the Earth's ecliptic orbit.Learn more in Our Moon
The moon completes one full rotation about its axis in the same time it takes Earth to complete a full revolution, resulting in one side always turning to face the parent planet in sync with its orbit. This phenomenon is known as tidal locking.Full Answer >
The Earth's moon takes 27 Earth days to completely orbit the Earth. A day on the moon is also equal to a little over 27 days on Earth.Full Answer >
Though the moon does rotate around its axis, the speed with which it completes these revolutions match the amount of time it takes to orbit around the Earth, leading the same side to be faced toward Earth at all times. This process takes a about month, meaning the moon's days are as long as an Earth month.Full Answer >
The National Aeronautics and Space Administration, known as NASA, officially began operation on October 1, 1958. Its creation was authorized by the National Aeronautics and Space Act, which was signed into law on July 29, 1958 by U.S. President Dwight D. Eisenhower.Full Answer >