Scientists were amazed after witnessing a distant quasar actually run out of gas.

In a study unveiled at the American Astronomical Society’s meeting in Florida recently, astronomers with the Sloan Digital Sky Survey (SDSS) found that there had been huge changes in quasar J1011+5442, according to a Phys.org report.

It’s an amazing thing to witness: things take so long to happen in space, usually millions if not billions of years, that we rarely witness anything actually happening in real time. But the SDSS allowed scientists to watch a quasar change in an incredibly short period of time.

Quasars refer to an incredibly bright beam of light caused by the ejection of energy from a massive black hole. This black hole in particular was 50 million times more massive than our sun — a number that is impossible for the human mind to even comprehend, especially considering the fact we can’t comprehend just how much bigger our sun is than Earth.

J1011+5442 was first observed all the way back in 2003. They were able to measure the quasar’s spectrum and therefore understand the gas that was being gobbled up by the black hole. Then, in early 2015, the SDSS measured another spectrum and found a huge decrease in the last 12 years. One scientist on the research team called it “stunning and unprecedented,” according to the report. The hydrogen-alpha emission had dropped by 50 percent in such a short period of time.

Scott Anderson, an astronomy professor at the University of Washington and the principal investigator, said in a statement: “”We are used to thinking of the sky as unchanging. The SDSS gives us a great opportunity to see that change as it happens.”