The Astronomy Thread

...the scientists have taken snapshots of the black holes' home galaxy over the past 12 years, using the Very Long Baseline Array, a system of 10 radio telescopes that stretch from the U.S. Virgin Islands to Hawaii and from New Mexico to Alaska.

In the new study, the scientists detected one of the black holes moving at the rate of just more than 1 micro-arcsecond per year. That's about 1 billion times smaller than the smallest thing visible with the naked eye, the researchers said.

"If you imagine a snail on the recently discovered Earth-like planet orbiting Proxima Centauri — a bit over 4 light-years away — moving at 1 centimeter [0.4 inches] a second, that's the angular motion we're resolving here," Romani said in the same statement.

This may be the smallest-ever movement detected of an object across the sky, the researchers said. "Personally, I find the technical tour de force of measuring this tiny motion most impressive," Romani told Space.com.

The new findings suggest that these black holes are orbiting each other, completing a single orbit over the span of about 30,000 years, the researchers said.​