THE HYDRA CONSTELLATION — In an astronomical first, scientists detected light and gravity from what they believe was the collision of two ultra-compact dense neutron stars in galaxy NG 4993.

First detected in 2013, a kilonova is a class of supernova explosion resulting from two colliding neutron stars.

The Space Telescope Science Institute says each neutron in this case was no wider than Washington, D.C. Typically, they're between 6 and 12 miles in diameter.

The Institute added that the stars in question weighed between 10 percent and 60 percent more than our sun."

What followed the kilonova is unknown, but NASA astrophysicist Eleonora Troja told Space.com the cosmic explosion may have a formed a black hole.