The sky around Dark Shark Nebula at true scale, north up and east left, with stars to magnitude 8. The circles show the field of a low-power eyepiece and of 10×50 binoculars.
Dark Shark Nebula is a reflection nebula in Cepheus, 1,110 light-years away
Dark Shark Nebula (vdB 150, LBN 546, DG 178) is a reflection nebula in the constellation Cepheus, 1,110 light-years away. spans 23′ of sky, about 7.4 light-years across. It is a telescope object, 6 inches or larger, and it is highest in the evening sky in October.
Nebula: a cloud of gas and dust. Emission nebulae glow on their own, lit by ultraviolet light from hot young stars; reflection nebulae shine by starlight scattered from dust; dark nebulae block the light behind them.
Dark Shark Nebula is vdB 150 in the Van den Bergh catalog of reflection nebulae
Sidney van den Bergh listed it in his catalog of reflection nebulae (1966), drawn from the Palomar Sky Survey. He chose nebulae lit by a star bright enough to appear in the Bonner and Cordoba star catalogs. The star that lights it is HD 210806, B8IV, magnitude 8.3. He rated it moderate in brightness and very blue in color.
Finding Dark Shark Nebula from Alfirk
Dark Shark Nebula lies 4.2° northeast of Alfirk, the magnitude 3.2 star. Three fingers held at arm's length cover about 5°.
Dark Shark Nebula is highest in the evening in October
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole northern hemisphere and south to about 17°S, and never sets north of 17°N.
Dark Shark Nebula is 1,110 light-years away
The light seen from Dark Shark Nebula tonight left it about 1,110 years ago, around 916 AD. It ranks 46 of 158 by distance among the Van den Bergh nebulae. Distance source: Gaia DR3 parallax of the illuminating star via AT-HYG v3.2 (340 pc).
