The Rho Ophiuchi Cloud Complex. Post-it Notes

The Rho Ophiuchi cloud complex. The Rho Ophiuchi cloud is found rising above the plane of the Milky Way in the night sky, bordering the constellations Ophiuchus and Scorpius. It's one of the nearest star-forming regions to Earth, allowing us to resolve much more detail than in more distant similar regions, like the Orion nebula. The amazing variety of colors seen in this image represents different wavelengths of infrared light. The bright white nebula in the center of the image is glowing due to heating from nearby stars, resulting in what is called an emission nebula. The same is true for most of the multi-hued gas prevalent throughout the entire image, including the bluish, bow-shaped feature near the bottom right. The bright red area in the bottom right is light from the star in the center, Sigma Scorpii, that is reflected off of the dust surrounding it, creating a reflection nebula. The much darker areas scattered throughout the image are pockets of cool, dense gas that block out the background light, resulting in dark nebulae. The bright pink objects just left of center are young stellar objects. These baby stars are just now forming; many of them are still enveloped in their own tiny compact nebulae. In visible light, these young stellar objects are completely hidden in the dark nebula that surrounds them. Also visible are some of the oldest stars in our Milky Way galaxy, found in two separate (and much more distant) globular clusters. The first cluster, M80, is on the far right edge of the image towards the top. The second, NGC 6144, is found close to the bottom edge near the center. They both appear as small densely compacted groups of blue stars. Globular clusters such as these typically harbor some of the oldest stars known, some as old as 13 billion years, born soon after the universe formed.