(CNN)Xheirst observation of a collision between neutron stars, detected in August 2017, created gravitational waves, light and heavy elements like gold and platinum. But astronomers have realized they also witnessed a kilanova, the kind of explosion that creates gold and platinum, the year before as well.
The 2017 observation offered evidence for the theory that such massive explosions in space are responsible for creating large amounts of heavy elements. All of the gold and platinum found on Earth was likely created by ancient kilanovae that resulted from neutron star collisions.
Because astronomers were able to make a direct observation in 2017, it changed what they expected a kilanova to look like. So they took their observations and looked back at other events initially thought to be something else.
Specifically, they looked at an August 2016 gamma-ray burst. The event, named GRB160821B, was tracked minutes after detection by NASA's Neil Gehrels Swift Observatory.
The 2017 event wasn't tracked in its initial hours, adding intrigue to the 2016 event.
The new analysis of the 2016 event was published Tuesday in the journalonthly Notices of the Royal Astronomical Society.
"The 2016 event was very exciting at first. It was nearby and visible with every major telescope, including NASA's Hubble Space Telescope. But it didn't match our predictions