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pmMeAllofIt t1_jb7iskw wrote

Reply to comment by Chichachachi in James Webb Telescope captures the same galaxy at three different points in time in a single mind-boggling image by mirzavadoodulbaig

It's one image, with the Supernova's galaxy appearing in it 3 times, at 3 different moments in time. The duration was estimated using scans from Hubble last year. Believing it to be a type Ia supernova (which all have the same luminosity) allowed them to plug the numbers and figure out the precise "prescription" of the lens that galaxy in the foreground is creating. JWST confirmed it's a type Ia supernova, which means their numbers are accurate.
 Lensing is pretty well understood and they have amazing software to help them out.

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doubletaxed88 t1_jb814uh wrote

How much of the night sky is lensed? Is there any estimates of how much you see is duplicates, or is it a rare occurance?

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daggada t1_jbabe9o wrote

I think for that to really come into play, you need to be looking pretty far. Like it's not something you'll really see in the stars you see at night with your eyes in our local galaxy.

But sure, looking into deep intergalactic space, which requires a decent telescope, it's probably not all that uncommon. Take a look at some of Webbs early pics, you'll see lots of warped and stretched images which I believe are examples of that phenomenon as well. And those are just in small patches of space.

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