What is the Cosmic Redshift?

Edwin Hubble discovered the expansion of the Cosmos by seeking the distance to the Andromeda Galaxy. What is the cosmic redshift and how was it found? This is part of my intro Astronomy class I taught at Willam Paterson University and CUNY Hunter.
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[@phdupont2500]

Dr. Kendall, I just wanted to drop you a note with my eternal thanks for placing this fantastic trove of information online and available to all. Your dedication of time, effort and knowledge is a beacon of light in the darkness. You’re a genuine quasar of informational dispersion, right here on our little blue marble in spacetime.

[@JasonKendallAstronomer]

Thanks for your kind note.

[@user-rv8gn5qf3o]

Great information video. I listen to your videos when I go to sleep @ night. And no, that’s not a bad thing lol

[@Choofalong]

OH MY GOD! The old version of this video is the first I EVER watched of yours! Looking forward to this one. What's another hour together after the last 200 or so I've already seen? Keep it up man, very much appreciate the effort you put in. EDIT: swear not stalking, just enjoy your content: G'day, from Down Under!

[@74wrighty]

Good to hear you give Humason some recognition. Most just mention Hubble.

[@frederf3227]

Quick Q: emission proper distance (A), reception proper distance (B), light travel distance (Z) is A

[@vanessacherche6393]

cool to see the data of things i've heard about. great lecture :)

[@vanessacherche6393]

i am guessing the sawtooth pattern in cepheids is caused by a fusion runaway with the tip of the tooth where expansion has cooled the star enough to dissipate energy on the more gradual curve of the downside. amazing that they can be at a ten day period, i'd have thought them on longer timescales.

[@vanessacherche6393]

i wonder how much these individual cepheids have accelerated their frequency over the last century... also where on the hr diagram do they tend to be?

[@sheph1145]

👍👍👍👍👍👍