Earth is 7 km per second faster and is about 2,000 light years closer to the supermassive black hole in the center of the Milky Way. These changes are the result of an improved model of our galaxy based on new observational data, including a catalog of objects observed for more than 15 years by the Japanese VERA radio astronomy project.
VERA began in 2000 to map space structures in the Milky Way. It uses a technique known as interferometry to combine data from radio telescopes scattered throughout the Japanese archipelago to achieve the same resolution as a 2,300 km diameter telescope would have. The precision of the measurement achieved with this resolution, 10 micro-seconds of arc, is sharp enough in theory to capture a five cent euro coin placed on the surface of the Moon.
Because Earth is located inside the Milky Way, we cannot step back and see what the galaxy looks like from the outside. Astrometry, the precise measurement of the positions and movements of objects, is a vital tool in understanding the overall structure of the galaxy and our place in it. This year, the First VERA Astrometry Catalog was published containing data from 99 objects.
Based on the VERA Catalog of Astrometry and recent observations by other groups, the astronomers constructed a map of position and velocity. From this map they calculated the center of the galaxy, the point around which everything rotates. The map suggests that the center of the galaxy and the supermassive black hole that resides there are 25,800 light years from Earth, closer than the official value of 27,700 light years adopted by the International Astronomical Union in 1985. The velocity component on the map indicates that Earth is traveling at 227 km per second as it orbits the galactic center. Faster than the official value of 220 km per second.
Now VERA hopes to observe more objects, particularly those near the central supermassive black hole, to better characterize the structure and motion of the galaxy. As part of these efforts, VERA will participate in EAVN (East Asian VLBI Network) comprised of radio telescopes located in Japan, South Korea and China. By increasing the number of telescopes and the maximum separation between them, EAVN can achieve even greater precision.