Deep in the Chilean desert, a nearly 40-foot-long telescope keeps watch over the stars above. It’s called the APEX telescope, and it’s the not-so-secret weapon of an ambitious project to map all of the Milky Way’s cold gas—the places where stars are born. Now, the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) project is complete, and scientists are marking its end with the release of a stunning new view of the galaxy.
The map you see above shows the biggest, most complete view of the cold galaxy ever made. Covering 140 degrees in length and three degrees in width of the southern plane of the Milky Way, it’s more than four times more detailed than the last map of the galaxy. Red portions of the map were taken by APEX, the background blue portions were taken by NASA’s Spitzer Space Telescope, and the faint red structures were taken by the ESA’s Planck satellite, which observes the universe’s background radiation. Check out the European Southern Observatory's website for more detailed views of the map.
It’s the result of a decade of observations of tiny wavelengths of radiation that fall between infrared light and radio waves on the electromagnetic spectrum. When the wavelengths hit the telescope, they are measured by the Large Apex BOlometer CAmera, or LABOCA, a kind of thermometer that measures the intensity of incoming radiation. Cooled to just a fraction above absolute zero, the camera detects tiny emissions from bands of dark gas and dust that can’t be viewed by the naked eye.
Why bother mapping a bunch of cold gas and dust? The answer isn’t just that they’re there—though that’s a good enough reason to map them in the first place. They’re the places where stars are born. When stellar gas and dust gets really cold, it clumps together and begins to collapse under its own weight. Those collapsing lumps of dust and gas eventually turn into stars.
By keeping an eye on pockets of cold, dense gas in the Milky Way, scientists can better understand how the next generation of the galaxy’s stars form. They hope to use the data to point them to places worthy of more research. There’s always room for further exploration—but the new map, with its spectacular visualization of the galaxy’s gaseous potential, is breathtaking in and of itself.