Scientists have documented evidence of gravitational waves created through the motion and collision of orbiting celestial objects.

In this latest 15-year-long study, NANOGrav researchers documented low-frequency waves created through the motion of some of the universe’s densest stellar objects. Researchers positioned telescopes across North America and pointed them at 68 pulsars — rapidly rotating neutron stars that send out radiation pulses at regular intervals, which can be detected as radio waves.

NANOGrav researcher Michael Lam from the SETI Institute told WFAA that in order to measure these gravitational waves, the team had to essentially create a detector for them that is “roughly the size of the galaxy.”

Scientists determined the presence of gravitational waves by analyzing the constant rates of radio waves coming from the pulsars and the time dilations created due to gravitational waves passing through the radio waves generated by the pulsars, which throw off the normal intervals at which those radio waves arrive here on Earth.

Changes in the rate of the “ticking” allowed scientists to verify the presence of these waves, essentially “hearing” them.

Whereas previous observations of these waves were of high-frequency events, this new study documents lower-frequency events caused by supermassive objects — some of the largest objects in our universe.

Gravitational waves are essentially ripples in the fabric of space and time caused by energetic or “cataclysmic events” in the universe. The existence of these waves was originally theorized by Albert Einstein in 1916 in his general theory of relativity, according to the Laser Interferometer Gravitational-Wave Observatory (LIGO).

“It’s really the first time that we have evidence of just this large-scale motion of everything in the universe,” said Maura McLaughlin, co-director of NANOGrav, according to WFAA.

The existence of these gravitational waves was originally proven when LIGO physically recorded these ripples in spacetime created by two colliding black holes 1.3 billion light-years away in 2015. However, those waves were of a higher frequency.

Gravitational waves are ordinarily generated by “violent and destructive” events, such as collisions between black holes. The organization reports that despite the magnitude of such events, when these waves typically reach Earth, they have a significantly lower frequency and are “thousands of billions of times smaller” than they were at their origin.

NASA announced that it found a binary system of black holes in 2022 where a supermassive black hole and a smaller companion were orbiting each other. Scientists attempted to document gravitational waves as their orbits decayed with an expected collision some 10,000 years in the future.

Szabolcs Marka, an astrophysicist at Columbia University, called pairs such as these the “tenors and bass of the cosmic opera,” according to WFAA.

Scientists have not determined an exact source for these newly observed gravitational waves but hope to use the data from this study to better understand the universe as well as these distant and massive celestial objects.