Most People Will Go Their Entire Lives Without Ever Knowing Why Airplane Windows Are Round

This is why:

Submarines have round portholes

Spacecraft use circular hatches

Pressure vessels are cylindrical or spherical

A rounded shape allows materials to handle internal pressure far more effectively.

In airplanes, windows are not perfectly circular but oval or rounded rectangles. This shape balances structural strength with practical concerns like visibility and space.

By eliminating sharp angles, engineers dramatically reduce the risk of crack formation and structural fatigue.

The change was so effective that after the Comet disasters, no modern commercial airliner has ever returned to square windows.

The Hidden Fatigue of Flight
One of the most fascinating aspects of airplane engineering is that planes are not designed to last forever. They are designed to survive a specific number of pressurization cycles.