Situated about 26,000 light-years from our sun, there is a supermassive black hole at the center of our Milky Way galaxy – and this beast’s name is Sagittarius A*.

For 27 years, researchers at the European Southern Observatory focused on one star named S2 that circled Sagittarius A*, and through painstaking observations, they were able to come to a familiar conclusion that has indeed become a tradition in the scientific community: Once again, Albert Einstein was right.

“Einstein’s general relativity predicts that bound orbits of one object around another are not closed, as in Newtonian gravity, but precess forwards in the plane of motion,” Reinhard Genzel, the director at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, said in a statement.

The study, which was published in the journal Astronomy & Astrophysics, detailed the star’s dance and stretched light as it orbited the supermassive black hole, which was predicted by Einstein’s theory of general relativity.

The European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert was used to make the observations. 

Isaac Newton’s theory of gravity suggested S2’s orbit would look like an ellipse, but observations showed that wasn’t the case. Instead, it was more of a rosette shape, which was within the bounds of Einstein's theory of relativity.

“This famous effect – first seen in the orbit of the planet Mercury around the sun – was the first evidence in favor of general relativity,” Genzel said.

“One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the center of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the sun.”

S2, which swings around Sagittarius A* once every 16 years, is considered to be one of the closest stars to be found orbiting a black hole. In its closest pass to Sagittarius A*, it comes within 12.5 billion miles – about four times as far as Pluto is from our sun. When S2 nears the black hole, it is moving at a mind-boggling 3 percent of the speed of light.

In the near future, more advanced telescopes, such as the European Southern Observatory’s Extremely Large Telescope, will enable astronomers to observe fainter stars that move even closer to a supermassive black hole like Sagittarius A*.

“If we are lucky, we might capture stars close enough that they actually feel the rotation, the spin, of the black hole,” Andreas Eckart, an astrophysicist at Cologne University and co-author of the study, said in a statement. “That would be again a completely different level of testing relativity.”

Ethen Kim Lieser is a Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV.