*H₂éwsōs or *Haéusōs is the reconstructed Proto-Indo-European name of the dawn goddess in the Proto-Indo-European mythology.

Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon. This morning twilight period will last until sunrise, when direct sunlight outshines the diffused light.