Why smoke particles turned the sky red

Most of us are familiar with the rhyme: Red sky at night; shepherds delight. Red sky in the morning; shepherds warning. But what about red sky in the middle of the day – what does that indicate?

The answer is high levels of particles in the sky coming from forest fire smoke. Videos showing this phenomenon in Sumatra, Indonesia, set Twitter alight on 21 September. The bright red haze more closely resembled Mars, than Earth.