dawn vs first light

dawn

• The morning twilight period immediately before sunrise. 

• The rising of the sun. 

• The earliest phase of something. 

• The time when the sun rises. 

• To begin to give promise; to begin to appear or to expand. 

• To begin to brighten with daylight. 

• To start to appear or be realized. 

first light

• The time when light first appears in the morning; dawn, especially the start of dawn. 

• The first use of a telescope or other instrument to capture an astronomical image.