Earth 16,000 MPH faster, 2,000 light years closer to the supermassive black hole at the center of the Milky Way

Earth just got 7 km / s (~ 16,000 mph) faster and about 2,000 light years closer to supermassive black hole in the center of the Milky Way Galaxy. But don’t worry, that doesn’t mean our planet is plunging towards the black hole. Instead, the changes are the results of a better model of the Milky Way based on new observational data, including a catalog of objects observed over more than 15 years by the Japanese radio astronomy project VERA. .

VERA (VLBI Exploration of Radio Astrometry, by the way “VLBI” stands for Very Long Baseline Interferometry) began in 2000 to map three-dimensional speed and spatial structures in the Milky Way. VERA uses a technique known as interferometry to combine data from radio telescopes scattered across the Japanese archipelago to achieve the same resolution as a telescope 2,300 km in diameter. Measurement precision obtained with this resolution, 10 micro-seconds of arc, is sufficiently sharp in theory to resolve an American penny 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 an essential tool for understanding the overall structure of the Galaxy and our place in it. This year, the first VERA Astrometry Catalog was published, containing data for 99 objects.

Based on the VERA Astrometry Catalog and recent observations from other groups, astronomers constructed a position and velocity map. From this map, they calculated the center of the galaxy, the point around which everything revolves. The map suggests that the center of the galaxy, and the supermassive black hole that resides in it, is located 25,800 light years from Earth. This is closer than the official value of 27,700 light years adopted by the International Astronomical Union in 1985. The speed component of the map indicates that the Earth is moving at 227 km / s as it revolves around the Galactic Center. . This is faster than the official value of 220 km / s.

VERA now hopes to observe more objects, especially 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) comprising a radio telescope located in Japan, South Korea and China. By increasing the number of telescopes and the maximum separation between telescopes, EAVN can achieve even higher accuracy.

“The first VERA astrometry catalog” by VERA collaboration et al. appeared in the publications of the Astronomical Society of Japan in August 2020.