The sky suddenly turned black and the sun turned red.

What you want to ask is why the sky suddenly turns black and the sun turns red? The reason for this is the following：

1, weather phenomenon: the sky suddenly turns black and the sun turns red. This is a weather phenomenon, which is caused by storms and lightning. Storms will darken the sky and the sun will be redder because of clouds.

2, natural disasters: natural disasters, volcanic eruptions, sandstorms, forest fires, causing the sky to darken and the sun to turn red, volcanic eruptions will release a lot of dust and volcanic ash, sandstorms and forest fires will have a lot of dust and smoke, making the sky darken and the sun turn red.