*_NASA GRAIL Mission Unveils Key Lunar Hemispheric Differences_* *Why in News* NASA’s GRAIL mission has uncovered major structural and thermal differences between the Moon’s near and far sides, providing new insights into lunar evolution. *Key Points* * *GRAIL Overview* : Launched in 2011, twin probes Ebb and Flow mapped the Moon’s gravity, offering deep data on its interior. * *Near vs. Far Side* : The nearside has volcanic plains and higher heat due to radioactive elements; the farside is rugged and cooler. * *Internal Composition* : The Moon's mantle, 80% of its mass, is hotter on the nearside by 100–200°C, likely due to past volcanism. * *Tidal Impact* : Earth’s gravity deforms the Moon, influencing its shape and surface behavior. * *Mascon Discovery* : GRAIL identified dense regions from ancient asteroid impacts, critical to lunar geological mapping.