In the weightlessness of orbit, an astronaut’s heart can become more spherical as it no longer works against gravity in the usual way, while their spine stretches enough to make them measurably taller before they return to Earth.

Freed from gravity, the body changes shape: a 2014 study found astronauts' hearts became about 9.4% more spherical, and spinal discs expand enough to add up to 3% in height. Both are temporary and reversible, and both reveal how much of our shape is the body bracing against gravity. The post In the weightlessness of orbit, an astronaut’s heart can become more spherical as it no longer works against gravity in the usual way, while their spine stretches enough to make them measurably taller before