Theia (/ˈθiːə/ THEE-uh) is a hypothesized ancient planet in the early Solar System which, according to the giant-impact hypothesis, collided with the proto-Earth around 4.5 billion years ago, with some of the resulting ejected debris re-coalescing to form the Moon. Collision simulations support the idea that the two large low-shear-velocity provinces in the Earth's lower mantle may be remnants of Theia. Theia is hypothesized to have been about the size of Mars and likely formed at the L4 or L5 Lagrange points of the Earth's orbit, although some hypotheses debatably suggested it may have formed in the Outer Solar System and later migrated into the Earth's orbit, and might have provided much of Earth's water.
___Origin_of_the_Moon_q.jpg)
>>>PUT SHARE BUTTONS HERE<<<
👉 Theia (hypothetical planet) in the context of Origin of the Moon
The origin of the Moon is usually explained by a Mars-sized body, known as Theia, striking the Earth, creating a debris ring that eventually collected into a single natural satellite, the Moon, but there are a number of variations on this giant-impact hypothesis, as well as alternative explanations, and research continues into how the Moon came to be formed. Other proposed scenarios include captured body, fission, formed together (accretion, synestia), planetesimal collisions (formed from asteroid-like bodies), and collision theories.
The standard giant-impact hypothesis suggests that a Mars-sized body called Theia impacted the proto-Earth, creating a large debris ring around Earth, which then accreted to form the Moon. This collision also resulted in the 23.5° tilted axis of the Earth, thus causing the seasons. The Moon's oxygen isotopic ratios seem to be essentially identical to Earth's. Oxygen isotopic ratios, which may be measured very precisely, yield a unique and distinct signature for each Solar System body. If Theia had been a separate protoplanet, it probably would have had a different oxygen isotopic signature than proto-Earth, as would the ejected mixed material. Also, the Moon's titanium isotope ratio (Ti/Ti) appears so close to the Earth's (within 4 parts per million) that little if any of the colliding body's mass could have been part of the Moon.