What happened during the collision between Earth and Theia 4.5 billion years ago?, Theia gently passed by Earth and slowly formed rings that turned into the Moon., A Mars-sized body called Theia struck the early Earth, ejecting molten rock and debris into space., How did the debris from the impact eventually form the Moon?, The debris orbited Earth, cooled, and gradually combined (coalesced) to form the Moon., The debris froze instantly and formed a solid Moon within a few days., Why does the Moon’s relatively large size support the Giant-Impact Theory?, A massive collision could provide enough material to create a large Moon compared to Earth., The Moon is large because it absorbed energy directly from the Sun., How did rock samples from the Apollo program provide evidence for the theory?, Samples from the Apollo program showed that Moon rocks are very similar in composition to Earth’s mantle., They proved the Moon is made entirely of ice and gas., What does the Moon’s small iron core suggest about its formation?, It suggests the Moon formed mostly from Earth’s outer layers, not from a large metallic core., It shows the Moon was once the center of Earth., What is the “isotope crisis” and why is it important?, It describes a time when the Moon ran out of radioactive material., It refers to the discovery that Earth and Moon rocks have nearly identical isotope ratios, which challenges the idea that Theia was very different from Earth., Why is it surprising that Earth and Moon rocks have nearly identical isotope ratios?, Because isotope ratios usually change every few million years., Because Theia should have had a different chemical fingerprint if it formed in another part of the solar system., Why is the predicted amount of Theia material in the Moon considered a problem for the theory?, The theory predicts 70–80% of the Moon should be from Theia, but evidence suggests most material came from Earth., Because scientists found no rocks on the Moon at all., How does angular momentum support the Giant-Impact model?, The current rotation and orbit of the Earth-Moon system match what scientists expect from a giant collision., It proves the Moon does not orbit Earth., Why does the Giant-Impact Theory remain the leading explanation despite the challenges?, Because scientists refuse to consider any other ideas., Despite challenges, it best explains the Moon’s size, orbit, composition, and the Earth-Moon system’s angular momentum..

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