Eli5: is it possible to know if there are galaxies hidden behind galaxies closer to us? And if yes, can we look at them with current technologies?
In: Planetary Science
Usually. Stars are incredibly small compared to the distances between them. Entire galaxies and pass through others without a single star colliding. Our own will be doing this with Andromeda in about 4.5B years but they’ll likely merge.
So when we look at distant galaxies, the stars we’re looking at can easily be ones that are closer or further away than the galaxy we see. We can calculate a star’s distance using parallax, red shift etc to work out which “dots” are part of the galactic cluster we’re examining.
But as for looking at an entire galaxy that might be behind another, we run into resolution and other limits in discerning that level of detail. So the practical answer is “usually not”.
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