Dawn or civil dawn is the time at which the sun is 6 degrees below the horizon in the morning. Civil dawn is defined as that time at which there is enough light for objects to be distinguishable and that outdoor activities can commence.

Nautical dawn is the time at which the sun is 12 degrees below the horizon in the morning. Nautical dawn is defined as that time at which there is just enough sunlight for objects to be distinguishable.

Astronomical dawn is the time at which the sun is 18 degrees below the horizon in the morning. Astronomical dawn is that point in time at which the sun starts lightening the sky. Prior to this time, the sky is completely dark.