Sometimes† space is just awesome. More specifically, stuff (or mass) in space has some properties that manifest in empirically awesome ways. Earlier this week, Science put out a report on a supernova (Wikipedia) observed behind a galaxy in the MACS J1149.6+2223 cluster. This particular supernova is visible due to gravitational lensing (Wikipedia) around the cluster, greatly magnifying the image.
But the incredible part about this imagery is that we’re seeing the same supernova repeating at different places close together in the sky. This is because the gravitational lensing is causing the light to take different paths, which means the photons received from each path have been traveling for a longer time than each other. Over approximately 9 billion light years, those subtle differences add up, so we’re seeing the supernova at different times in its history simultaneously.
Galaxy in Front of Supernova Creates Cosmic Mirage: Einstein Cross (National Geographic):
Far, far away, a galaxy is acting as a cosmic split-screen. Parked in front of an exploding star, the galaxy’s gravity is projecting magnified images of the supernova onto the sky—four images, to be precise, in a celestial mirage called an Einstein Cross.
The weirdness doesn’t end there, though. Within the next decade, the cosmos will replay that exact same explosion, in a different spot in the sky.
- Astronomers Watch a Supernova and See Reruns (The New York Times)
- Hubble sees supernova split into four images by cosmic lens (Astronomy)