S 155

S 155

Emission nebula
S 155
Observation data: J2000.0 epoch
Right ascension	22^h 57^m 17.14^s
Declination	+62° 28′ 33.4"
Distance	2400 ly
Apparent magnitude (V)	7.7
Apparent dimensions (V)	50.0'x30.0'
Constellation	Cepheus
Physical characteristics
Radius	35 ly
Absolute magnitude (V)	16
Designations	Sh2-155, Caldwell 9

S 155, also known as the Cave Nebula, Sh2-155 or Caldwell 9, is a dim and very diffuse bright nebula within a larger nebula complex containing emission, reflection, and dark nebulosity. It is located in the constellation Cepheus.

Visually it is a difficult object, but with adequate exposure, makes a striking image. The nebula gets its name Cave Nebula from the dark lane at the eastern side abutting the brightest curve of emission nebulosity which gives the appearance of a deep cave when seen through a telescope visually.

References

Patrick Moore (1990). The Amateur Astronomer (11th ed), W.W. Norton & Company, ISBN 0-393-02864-X

External links

• S 155 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• The Scale of the Universe (Astronomy Picture of the Day 2012 March 12)