China has just built one of the largest cosmic listening devices ever. Called the Five-hundred-meter Aperture Spherical Telescope or FAST, the instrument’s vast signal-gathering dish spans 1,640 feet (500 meters) across or nearly 5 football fields placed end to end. FAST was built directly into a natural depression deep in the mountains of Guizhou province in southwestern China at an extremely “radio quiet” site. To ensure that no stray magnetic fields would interfere with the telescope, the Chinese government moved about 9,000 former residents of the area to neighboring counties.
It’s the largest telescope of its type, nearly 200 meters bigger and 10 times more sensitive than the Arecibo radio telescope in Puerto Rico, which was also built into a natural depression. China sees the giant ear as another part of its plan to become a superpower in space, both on Earth in terms of telescope technology and in space with planned missions to the moon and the building of a larger space station on its checklist.
So what can you see with this thing? Since it’s not an optical telescope but instead detects radio waves, it doesn’t show traditional views of the cosmos. However, the signals gathered can be reconstructed to create either black and white or color-coded images the same way the Arecibo telescope pings a near-Earth asteroid to build up a picture showing its shape and surface features. Also, the strength of radio waves given off by different regions of a glowing cloud of dust and gas such as the Orion Nebula can be converted into brighter and darker areas to fashion an image in radio light.
The Chinese plan to use their new dish to look farther into space than ever before listening for possible signals from extraterrestrial civilizations. They’ll also seek exotic pulsars (rapidly-spinning city-sized stars left in the wake of supernovae explosions), never before detected molecules in space and join other radio telescopes in an Earth-spanning array to resolve and image some of the smallest objects in our galaxy including its central black hole.
On a completely different tack, watch the southwestern sky tonight for a beautiful conjunction of the planet Jupiter and the crescent moon. No giant telescope required!