School help (science)?

So I kinda spaced out in class and I have no idea what this even means.
So we have a chart and it has galaxies with their velocities and distances from earth. The question is "Which galaxy has the biggest redshift?"
I looked up redshift but still dont undersatnd what it means


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Most Helpful Guy

  • As things get further and further away, the light waves get slower and slower.

    Faster wavelengths appear blue. Slower ones appear red. So when something gets further away, the light waves take longer to reach you and slow down, meaning they're more red.

    In other words, the further something is away, the more red it will appear.

    With this logic, "Which galaxy has the biggest redshift" means "Which galaxy has the slowest light waves",

    OR

    "Which galaxy is the furthest away?"

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    • Thank you! c:

    • You can witness this effect by being near a passing train or car. The sound of the vehicle has a higher pitch while it is approaching you, but a lower pitch after it passes.

      Red shift is the equivalent of that lower pitch. Now that the train (or galaxy) is moving away from you, it gives off a lower pitch (or color).

    • It's sort of like sound, louder sounds contain sound waves that are closer together, but as they die off or "decay", the waves get further apart. Light is the same way, with the stuff as at the higher end of the spectrum spacing out more as it moves through space. If you want bonus points you can say that light decays at an inverse square rate, meaning if you want to know how much light will be left at a certain distance, you multiply it by one divided by the square of the distance. That's how people calculate how far away galaxy is, they measure the "redshift", and using a spectrometer determine what materials a star is made of, and how much light it should put out, and compare that to how much light is actually visible, basically doing the inverse square equation backwards

What Guys Said 1

  • Bigger redshift means higher velocity, to make it as simple as possible. So the galaxy moving the fastest away from us has the biggest redshift.

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