IC 4592 The Blue Horse Reflection Nebula

Reflection nebulas are made up of very fine dust that normally appears dark but can look quite blue when reflecting the light of energetic nearby stars. In this case, the source of much of the reflected light is a star at the eye of the horse. That star is part of Nu Scorpii, one of the brighter star systems toward the constellation of the Scorpion (Scorpius). A second reflection nebula dubbed IC 4601 is visible surrounding two stars to the right of the image center. (https://science.nasa.gov/ic-4592-blue-horsehead-reflection-nebula)