What is Luminous matter?

Luminous matter is stuff that gives off light, just like a glowing nightlight in your bedroom.

Imagine you're in your room at night, and you turn on a small nightlight, it shines softly, making the room not completely dark. That's kind of what luminous matter does in space. It's matter, stuff made up of tiny particles called atoms, that glows because it’s hot, just like your nightlight is hot inside.

Think of a firefly, when it flashes, it gives off light. That’s because the firefly is luminous matter too! In space, stars are like giant fireflies: they're made of luminous matter, and they shine because their insides are super hot.

Sometimes, luminous matter isn’t just in stars, it can be in clouds of gas or even in the dust between stars. When this stuff gets heated up, like when a star is nearby, it starts to glow. It's like when you heat up a piece of metal on a stove, it glows red hot.

So luminous matter is just stuff that gives off light because it’s hot, and we can see it shining in the night sky!