Ask Dr. Universe

What is fire? Asked by Anish P., 10, Nepal.

Dear Anish,

There’s nothing like taking a little catnap by the fireplace, feeling the heat, watching the flames, and listening to crackling sounds. But until you asked, I wasn’t entirely sure what this mesmerizing thing was or how it works.

I decided to find out from my friend Michael Finnegan. He’s a chemistry professor here at Washington State University.

In the 4th grade Finnegan got a chemistry set that came with a chemistry book. He read about how everything around us is made up of building blocks called atoms. He learned how atoms get together...