das Morgengrauen
dawn
The time very early in the morning, shortly before the sun rises and the sky slowly becomes light.
Im Morgengrauen brachen die Wanderer zu ihrer Tour auf.
At dawn, the hikers set off on their tour.

dawn
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dawn
The time very early in the morning, shortly before the sun rises and the sky slowly becomes light.
Im Morgengrauen brachen die Wanderer zu ihrer Tour auf.
At dawn, the hikers set off on their tour.

The word consists of 'Morgen' (morning) and 'Grauen'. Here, 'Grauen' does not refer to horror, but to the color 'grau' (gray). It describes the gray, dim light in the early morning.
Das erste graue Licht des Tages nennt man Morgengrauen.
The first gray light of the day is called 'Morgengrauen' (dawn).
This word is almost always used with the preposition 'im' to indicate a point in time. The fixed expression is 'im Morgengrauen' (at dawn).
Die Vögel beginnen im Morgengrauen zu singen.
The birds begin to sing at dawn.
'Morgengrauen' (dawn) has a somewhat poetic or literary effect. In everyday spoken language, people would often simply say 'sehr früh am Morgen' (very early in the morning).
Der Roman begann mit einer Beschreibung der Landschaft im Morgengrauen.
The novel began with a description of the landscape at dawn.
sunrise
'der Sonnenaufgang' and 'das Morgengrauen' are close in time and both have to do with the early morning. 'Das Morgengrauen' is the time shortly before sunrise, when the sky slowly becomes lighter. 'Der Sonnenaufgang' is then the moment when the sun visibly comes up over the horizon. The words can be confused because you use both when talking about getting up early, traveling, or observing nature. As a guide: first comes 'Morgengrauen' (dawn), then 'Sonnenaufgang' (sunrise).

Im Morgengrauen machten sich die Eltern auf den Weg zum Bahnhof.
At dawn, the parents set off for the train station.
Lea blieb am Strand, bis der Sonnenaufgang zu sehen war.
Lea stayed on the beach until the sunrise was visible.