NASA’s Hubble Space Telescope captured three separate moments
in a far-off supernova explosion in a single snapshot.
These moments provide a unique glimpse into the supernova’s early life.
It is quite rare to detect a supernova explosion at a very early stage,
because that stage is so short.
It only lasts for hours to a few days, and it can be easily missed.
The star exploded more than 11 billion years ago, when the universe was less than one fifth
of its current age of 13.8 billion years.
In a single exposure, Hubble captured the supernova’s rapid change of color, which
indicates temperature change.
The early, hotter phase appears blue.
As the supernova cooled, its light turned redder.
This detection was possible through a phenomenon called gravitational lensing, as first predicted
by Einstein’s theory of general relativity.
In this case, the immense gravity of the galaxy cluster Abell 370 both bent and magnified
the light from the more distant supernova located behind the cluster,
like a giant cosmic lens.
This lensing effect split and warped the supernova’s light,
bending it along separate pathways of varying lengths.
The different travel times between each path created a time delay that produced three distinct
images of the explosion at different times that arrived at Earth simultaneously.
This is the first detailed look at a supernova
at such an early time of the universe’s evolution.
The research could help scientists learn more about the formation of stars and galaxies
in the young universe.
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