Which scenario best describes the Moon's formation according to widely accepted scientific theory?

• A. The Moon formed independently and was captured by Earth's gravity.
• B. A large meteorite collided with Earth, ejecting debris that eventually formed the Moon.
• C. The Moon formed from volcanic activity on Earth spreading into orbit.
• D. The Moon formed separately around the Sun and was later captured by Earth.

Answer: (B)

The main idea being tested is how the Moon most plausibly formed. The widely supported view is the giant impact scenario: a Mars-sized body collided with the early Earth, ejecting a disk of molten debris that orbiting Earth gradually coalesced into the Moon. This explains why the Moon’s rocks and isotopic composition are so similar to Earth’s mantle, yet the Moon has a relatively small iron core and is depleted in volatiles due to the high heat of the impact. The resulting debris disk would naturally form a near-equatorial, prograde orbit and impart the Earth–Moon system with its characteristic angular momentum, matching what we observe today and the Moon’s formation timeline.

Other scenarios don’t fit as well with the data. A Moon captured from elsewhere would likely carry a different isotopic fingerprint and a more irregular orbit, while formation from Earth’s volcanism or a fission-like process would leave distinct chemical and geologic signatures that aren’t observed. A Moon that formed separately around the Sun and was later captured also requires unlikely conditions to end up in a stable, near-equatorial Earth orbit.