the.com/tropic
the invisible line where the sun stands directly overhead, then loses its nerve
means Either of the two parallels of latitude (about 23.5° north and south of the equator) marking the limits where the sun can appear directly overhead, or, loosely, the hot region between them.
from From Greek 'tropikos,' meaning 'of a turning,' rooted in 'tropos,' a turn or turning. The 'turn' is the sun's: at these latitudes the sun reaches its highest point at the solstice and then appears to reverse course, swinging back toward the equator. The same 'turning' root spins through words like 'heliotrope' (turning toward the sun) and 'trophy' (originally a turning-back of the enemy).
latitudeDrawn at roughly 23.5 degrees north and south
driftingBoth tropics move about 15 meters yearly
named forGreek tropos, the sun's turning point
sign swapCancer and Capricorn mark each line
between themEarth's only zone where sun hits vertical