Rho Ophiuchi Nebulosity
Ophiuchus-Scorpius Boundary Near Antares
Object Info

This image spans the boundary between the constellations Ophiuchus and Scorpius. The bright orange object at lower left is the star "Antares" or Alpha Scorpii. Blue reflection nebulae extend along the constellation boundary from the triplet star Rho Ophiuchi ending with a nebula designated IC4603. Another small reflection nebula surrounds star 22 Scorpii at left-center. The red nebulosity near right-center surrounds star Sigma Scorpii. Two globular star clusters are also discernable as white fuzzy patches near the bottom of this image. The brightest is M4 directly right of Antares; the other above and slightly left of Antares is designated NGC6144. Both these clusters are much more distant than any of the stars or nebulae in the image. Left-Click the center of the image to see object labels.

Reflection nebulae are cold interstellar clouds of dust and gas which reflect light of nearby stars. Red light passes through or is absorbed by these cold clouds while blue light is scattered or reflected consequently they usually appear bluish in astrophotos. Emission nebulae are warmer clouds of gasses, mostly hydrogen, which fluoresce with a red light when illuminated by ultraviolet radiation from nearby stars. The yellowish cloud around Antares is a combination of both types.