"Seen in visible light, these regions of the Universe are often dark and obscured due to the dust," the European Southern Observatory's website explains. "But they shine brightly in the millimetre and submillimetre part of the spectrum. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe, whose light has been redshifted into these longer wavelengths."
APEX uses nearly 300 high-tech sensors kept at just 0.3 degrees above absolute zero to monitor minuscule changes in temperature. When incoming radiation meets one of the telescope's many detectors, it notes the resulting temperature increase and uses it to map cold swaths of gas and dust.
The new map covers an area of sky 140 degrees long and 3 degrees wide, which is more than four times the size of ATLASGAL's previous release. In the video and image above, you can see the ATLASGAL data in red. The background image — the blue stuff — comes from shorter infrared wavelength observations made by NASA's Spitzer Space Telescope. The European Space Agency's Planck satellite provided more data to complete the picture, contributing the fainter red structures shown. The Planck satellite covers the entire night sky, but it does so at a lower resolution than APEX surveys the southern sky — which is where we can observe our galactic center. You can zoom in on the massive full-sized version of the image here.