The black hole's extreme gravity has stretched the gas cloud, dubbed G2, into a thin strand like a piece of spaghetti, they said.
Astronomers are taking advantage of the opportunity to catch the phenomenon of a gas cloud ripped apart and eaten by a black hole, a recurring cosmic event.
The gas cloud, three times larger than Pluto's orbit and first spotted on its course toward the galaxy's center in 2011, has entered the black hole's gravitation field, causing it to accelerate around the black hole and speed back towards us.
"The most exciting thing we now see in the new observations is the head of the cloud coming back towards us at more than 10 million kilometers per hour (6.2 million mph) along the orbit -- about 1 percent of the speed of light," Reinhard Genzel from the Max Planck Institute for Extraterrestrial Physics in Germany told the BBC.
The origin of the gas cloud remains unclear, astronomers said.
"At the moment we think that the gas probably came from the stars we see orbiting the black hole," Stefan Gillessen, also from the Max Planck Institute, said.