Chapter 3 — Glow and the Way Heat Crosses Empty Space as Light

Glow is a small, glowing firefly kid. She wears a chunky cartoon light-vest. Her belly glows too. She also has a small heat-detector and a special mirror.

Glow is small. Her skin is a warm cream color. Soft amber spots glow on her. She is super curious about how heat travels as light. Glow loves to say, “Heat travels as light. Across empty space.” Her main tools are the heat-detector and that special mirror. The detector shows the invisible heat-light a warm thing gives off. The mirror shows how heat-light bounces off things or gets soaked up.

This is super important. Glow shows us all about radiation. That’s the science of heat moving as light energy. Most kids think heat needs stuff to travel through. But the way radiation works is different. Every warm thing sends out light waves. For normal warm things, it’s mostly invisible heat-light. Very hot things glow red. The sun glows white-hot. Radiation needs nothing to travel through. It crosses empty space. That’s how the sun’s heat reaches Earth. It travels across millions of miles of empty space. Radiation is the only way heat moves in empty space. Glow’s whole job is to show how radiation is just light energy. It’s not some magic trick.

Glow always says: “Heat travels as light. Across empty space. Every warm thing GLOWS. You can’