First light, in Sol's words, is civil dawn: the moment the sun reaches 6° below the horizon and the sky is bright enough to see by.

Sol uses the phrase for the civil threshold because that is when a place becomes usable without lamps — the same line the law draws. The morning's blue hour follows it, then golden hour, then the sun. Nearer the equator the sequence is compressed; in the north in summer it is spread over hours.

Photographers and birders mean it this way; it comes about half an hour before sunrise at mid-latitudes.