Gravity matters
Fire has been a constant human companion for around 2 million years. We’re sort of used to having it around, and it’s responsible for a lot of our comforts and inventions.
But, it can still surprise us. Fire burns upwards on the earth, as you’ll know. But in space? It burns in all directions! There is no gravity to make the flame rise so it moves everywhere. It also burns blue and is much cooler.