True weightlessness occurs only infinitely far from all masses (theoretical).

Apparent weightlessness occurs when the support force (normal force) is zero:

• Inside a freely falling elevator (a = g)
• Inside an orbiting spacecraft (continuous free fall)
• At Earth's centre (g = 0 from all directions)

Key misconception: Astronauts in the ISS are NOT beyond gravity. At 400 km altitude, g ≈ 8.7 m/$s^2$ (89% of surface g). They feel weightless because both they and the spacecraft are in free fall — there is no contact force.

Apparent weight on an orbiting spacecraft = 0 regardless of the orbit altitude (as long as the craft is in free fall and not thrusting).