A new look deep into the heart of our Milky Way Galaxy comes closer to the central supermassive black hole than ever before, promising a way to see the very shadow of the mysterious object in coming years.

Astronomers have for 30 years sought to learn exactly what causes the radio emissions and how near to the black hole they originate. The radio-emitting region is no more than 186 million miles (300 million kilometers) across, or less than the diameter of Earth's orbit, the researchers reported Thursday in the online edition of the journal Science.

"We don't know yet the complete nature of the radio emitting region, but as a result of our measurement we now have a tight constraint on its size," said Geoffrey Bower of the University of California-Berkeley. "We are much closer to seeing the effects of a black hole on its environment here than anywhere else."

Bower told SPACE.com that the radio emissions might originate from material that is falling onto the black hole, or perhaps they are spawned by a jet of stuff flowing away from the black hole at a significant fraction of the speed of light.

Further observations may solve that remaining mystery, he said.

For now, the new observations come closer to a black hole -- as measured in relation to the presumed size of the given black hole -- than any previous, Bower said. The primary work was done with the National Science Foundation's Very Long Baseline Array of telescopes.

The radio-emitting region is called Sagittarius A* (meaning A-star). It was discovered in 1974 and later determined to be associated with a central, supermassive black hole. The whole setup is about 26,000 light-years from Earth.

The area is shrouded in dust, so visible-light telescopes can't study Sagittarius A*. Radio waves penetrate the dust but are scattered by the turbulent, hot gas in the area. The astronomers said this scattering had frustrated previous attempts to peer into the very core of the action. Bower likened the task to trying to spot a yellow rubber duck through the frosted glass of a shower stall.

To cut through the cosmic fog, the team employed higher radio frequencies, which correspond to shorter wavelengths. They also used longer wavelength observations to determine the effects of the scattering, then removed those effects from the short-wavelength data.

"After 30 years, radio telescopes finally have lifted the fog and we can see what is going on," said fellow investigator Heino Falcke of the Westerbork Radio Observatory in the Netherlands.

The researchers say the new observations rule out some less popular ideas for the cause of the radio emissions.

"Imaging the shadow of the black hole's event horizon is now within our reach, if we work hard enough in the coming years," Falcke said.