New data puts Earth closer to Milky Way’s center
Earth is 2,000 light-years closer to galactic center than we thought
For two decades the Japanese VERA radio astronomy project has been gathering data to build up a 3D map of the position and velocity of objects revolving in our galaxy. The latest analysis indicates that the Earth is 2,000 light-years closer to the center of the galaxy and traveling 4.3 miles per second (7 km/s) faster than previously estimated.
Radio astronomers in the 21st century have much in common with the earliest map makers, and for the same reason. When people like the ancient Greek geographer Ptolemy started to figure out what the Earth looked like, they were hampered by the fact that they were pretty much stuck in one place and had to rely on limited data. The same is true of radio astronomers, who are trying to map the Milky Way galaxy, but are hampered by living inside of it.
Not only do galactic cartographers have only the haziest idea of what the opposite side of the galaxy looks like, they also have trouble figuring out exactly where the Earth sits in relation to the galactic center and the supermassive black hole that resides there. Since 1985, the best estimate by the International Astronomical Union was that we were 27,700 light years from galactic center and traveling at 137 miles per second (220 km/s).
The VERA Very Long Baseline Interferometry (VLBI) project creates 3D maps by combining data from two or more different radio telescopes and examining how one set of data interferes with another to form a pattern. With enough telescopes hooked up across Japan, the team had what was effectively a giant instrument equivalent to a 1,400 mile-wide radio dish with a theoretical resolution that could see a penny on the Moon.
Now, collected in the First VERA Astrometry Catalog, data from 99 galactic objects as well as from other research groups has been used to produce a more accurate model of the structure of the Milky Way. The calculations indicate the Earth is really 25,800 light-years from galactic center and traveling at 141 miles per second (227 km/s).
The next step in the project will be to examine objects closer to the central black hole by combining VERA with the East Asian VLBI Network (EAVN, which includes radio telescopes in Japan, South Korea, and China.
The research was published in Publications of the Astronomical Society of Japan.