Gravity feels steady. You drop a set of keys, and they fall the same way every time. That reliability makes it tempting to picture Earth’s pull as uniform. After accounting for Earth’s rotation, gravity is slightly weaker beneath Antarctica than anywhere else on the planet. That weakness creates a kind of “gravity hole,” a broad low in the field that helps shape the sea surface around the southern continent. A study published recently in Scientific Reports argues that this oddity did not appear overnight. Instead, it reflects extremely slow shifts of rock deep inside Earth, unfolding over tens of millions of years. The authors also point out a striking overlap in timing: the study’s major changes in the Antarctic gravity low line up with major changes in Antarctica’s climate system, including the onset of widespread glaciation. Present-day geoid anomalies. (A) Nonelliptical geoid undulations, derived from the GRACE geopotential. (B) Nonhydrostatic geoid undulations derived from the GRACE geopotential solution2 relative to Earth’s hydrostatic ellipsoidal figure, arising from the diurnal rotation. (CREDIT: Scientific Reports) A low spot …