Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2023 September 26

A starfield surrounds a large nebula that is mostly brown
and blue and has an appearance reminiscent of the head of a horse.
This nebula is not the more famous

IC 4592: The Blue Horsehead Reflection Nebula
Image Credit & Copyright: Antoine & Dalia Grelin

Explanation: Do you see the horse's head? What you are seeing is not the famous Horsehead nebula toward Orion, but rather a fainter nebula that only takes on a familiar form with deeper imaging. The main part of the here-imaged molecular cloud complex is reflection nebula IC 4592. Reflection nebulae are made up of very fine dust that normally appears dark but can look quite blue when reflecting the visible 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 above and to the right of the image centre.

Tomorrow's picture: steve X


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