Meanings of glowed dull in English

At one point the tunnel wall became so hot, it glowed dull red.

A sudden, ear-splitting crash, a groan of tortured metal, and the barricaded hatchway glowed dull red.

Within these grains whose existence was more sensed than seen glowed dull red light, smoky and sullen.

The coal-dust suspended in the air of the hold had glowed dull-red at the moment of the explosion.

The high walls of the town still caught the sunset and glowed dull red against the darkening sky.

The three identical planets-PebblesOne, Two, and Three-abruptlyglowed dull orange, then red, then white, in sequence according to their distances from the ship.