Listen again · In Conversation
New evidence may explain why the Moon has two different faces October 15, 2026 · 3:50 · Science and the planet · With Maya and Nora
I’m Maya, and Nora is our columnist for science and the environment. Nora, why does the Moon have two very different sides? The Moon’s near side, which faces Earth, has broad, dark plains made by ancient volcanoes.
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Maya Welcome to Slow English FM. This is Science and the Planet, where we explore science and the environment in clear English to help us understand the world. I’m Maya, and Nora is our columnist for science and the environment. Nora, why does the Moon have two very different sides? Nora The Moon’s near side, which faces Earth, has broad, dark plains made by ancient volcanoes. The far side has more old, cratered highlands, a thicker crust, and fewer volcanic plains. Researchers have now proposed a possible explanation for how that contrast formed. Maya What new evidence did they use? Nora A team led by Hejiu Hui of Nanjing University studied rocks brought back from the far side by China’s Chang’e-6 mission. They compared them with near-side samples collected by the Apollo missions and China’s Chang’e-5 mission. Chang’e-6 returned the first samples from the Moon’s far side in 2024, according to China’s National Space Administration, which carried a report from Xinhua. Maya Why does having far-side rocks matter? Nora Before Chang’e-6, researchers had far fewer rocks collected directly from the far side to compare with near-side samples. These new samples let the team compare material from both sides. That gives them evidence to test ideas about how the difference developed. Maya So what is the team’s explanation? Nora The team proposes that, after the Moon became locked so that the same side always faces Earth, Earth’s pull heated the near side more strongly. Their model says this difference in heat could have moved molten rock through the early Moon. Lighter, magnesium-rich material may have shifted toward the far side, while materials that produce heat became more concentrated on the near side. Maya Could you explain “tidal heating” in simple terms? Is it the same idea as the tides in Earth’s oceans? Nora It is related to the same kind of gravitational pull. In this proposed model, Earth’s pull caused more heating inside the Moon’s near side. That heating, the researchers suggest, helped drive movement in the Moon’s ancient, molten interior. The team’s explanation is a model, though—not a settled answer. Maya How certain can we be that this is the answer? Nora We should be careful. ScienceDaily’s report, based on story materials from Science China Press, describes this as a possible explanation. A research news release from Science China Press says other ideas have also been proposed, including a giant impact and uneven cooling. It says the origin of the difference is still debated. The new samples add evidence, but they do not settle the question by themselves. Maya What does this change in how scientists study the Moon? Nora It gives researchers a direct way to compare rocks from the two sides, rather than relying mainly on samples from the near side. In my view, that is the key step: the new material can help scientists test explanations against rocks from both regions. Whether this particular model holds up will depend on further study. Maya Nora, thank you. And thanks for listening to Science and the Planet on Slow English FM.
