Rho Ophiuchi might look like an abstract painting, but this splash of colors is in fact a busy star-forming complex. WISE, NASA's Wide-field Infrared Explorer captured the picturesque image of the region, which is one of the closest star-forming complexes to Earth.
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 what is called a reflection nebula. And the much darker areas scattered throughout the image are pockets of cool, dense gas that block out the background light, resulting in absorption (or 'dark') nebulae. WISE's longer wavelength detectors can typically see through dark nebulae, but these are exceptionally opaque.
The bright pink objects just left of center are young stellar objects--baby stars just beginning to form. Many of them are still enveloped in their own tiny compact nebulae. In visible light, these baby stars are completely hidden in the dark nebula that surrounds them. Also seen in this image are some of the oldest stars in our Milky Way galaxy. 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.