An international team of researchers recently discovered two black holes merging with one another.

Black holes are certainly among the most ominous features lurking in space, but it turns out they can get even scarier.
In December, an international team of researchers discovered two of them merging with one another, according to a recent press release by Northwestern University.
The incredibly powerful intermingling was detected via gravitational waves, which are also often referred to as ‘ripples in the fabric of spacetime.’ 
What resulted was a single, yet very large, vortex, estimated to be roughly 21 times the mass of our sun. 
This was the second such joining of forces observed in the recent times. 
The first ever black hole collision and combination recorded was detected just months prior. 
The two gravitational juggernauts involved in that event were significantly larger, resulting in a mass greater than 60 suns. 
Both events were picked up by equipment at the Advanced Laser Interferometer Gravitational-wave Observatory, which is located in the U.S.