Why are there eight unique gluon states, and not six or nine in quantum chromodynamics?

Watch me ramble about trying to understand why there are 8 gluon states, and not 9. Ultimately, I dont know, but I think I've come up with a fairly compelling way of helping students visualise what's going on.

⭐️ 𝗟𝗶𝗻𝗸𝘀 ⭐️