Why can ultrasound show baby pictures?

Answer: Sound waves bounce off tissues

Sound waves bounce off tissues ✓ — Correct! Ultrasound sends high-frequency sound waves (above 20 kHz) into the body. Different tissues (bone, muscle, fluid, soft tissue) reflect sound differently based on density. Echoes return at different times and strengths. A computer analyzes these returning echoes to construct an image showing tissue boundaries and structures. It's like echolocation (how bats see)—using sound reflections to 'see.'

It uses X-rays safely — Wrong. Ultrasound uses sound waves, not X-rays. X-rays use ionizing radiation (potentially harmful, especially to developing fetuses), while ultrasound uses harmless sound waves—same physics as your voice, just higher frequency. This is exactly why ultrasound is preferred for pregnancy imaging—it's safe. X-rays would risk harming the developing baby.

Babies glow in ultrasound light — Wrong. Ultrasound doesn't use light, so nothing 'glows.' It uses high-frequency sound waves that penetrate the body and reflect off tissue boundaries. The returning sound echoes are detected, timed, and analyzed by computer to construct an image. The display you see is a computer-generated visualization of sound reflection patterns, not light, glow, or illumination.