i know its measured in lightyears but im watching a video on the james webb telescope and the discovery of huge galaxies and how we have to rethink the beginning but how do they know how old the galaxies are by just pictures? i imagine they have a lot of other things that tell them more information but still. it seems damn near impossible to even tell what anything is especially with how small and warped it is too. thank you i appreciate any info on this. im just throwing the math flair since theres no space
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Stars look white but that white light is made up of lots of different colors. If you put that light through a prism, you get a spectrum of all the colors, but because of the elements in the stars, there are specific lines of that spectrum.
If we look at the light from a distance galaxy, those same lines show up, but they are shifted based on the motion of the galaxy in relation to us, and the amount of the shift depends on their velocity.
We know that the larger the red shift is, the farther away the galaxy is, and therefore the older it is since it took the light a long time to reach us.
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