Old Supernova

 

Two Hubble images show the galaxy cluster MACS J0138. In the 2016 image, light from the ancient Supernova Requiem appears in three different spots simultaneously on the edge of the cluster (circled in white). In the 2019 image, they are gone.  (Image credit: NASA/ Joseph DePasquale)

The universe is an endless expanse of mystery, majesty and mind-blowing spectacle. So why, a few years from now, is the cosmos airing a "rerun" of a supernova explosion that we already watched in 2016?

Known as Supernova Requiem, the faint glint of an ancient, 10 billion-year-old explosion is expected to reappear in the sky sometime around the year 2037 — even after the same light source already smiled for NASA's Hubble Space Telescope three times in 2016.

The reason for this cosmic rerun doesn't have anything to do with the supernova itself, research published Sept. 13 in the journal Nature Astronomy suggests, but with the gargantuan cluster of galaxies that the nova's light has to pass by on its way to Earth.

"Whenever some light passes near a very massive object, like a galaxy or galaxy cluster, the warping of space-time that Einstein's theory of general relativity tells us is present for any mass, delays the travel of light around that mass," lead study author Steve Rodney, an assistant professor at the University of South Carolina in Columbia, said in a statement.

This phenomenon is called gravitational lensing. The effect occurs when a gravitationally massive object warps or lenses the light of distant stars and galaxies behind it — sometimes magnifying the light of distant objects, and sometimes distorting it. In the case of Supernova Requiem, the large galaxy cluster MACS J0138 is causing the stellar explosion's light to brighten, multiply and split into several different images, seemingly appearing at different points in the sky at different times, the researchers said.  READ MORE