system
Given the following post, respond as if you're commenting on Reddit:
human
Can X-rays be red-shifted until they're visible to humans?
gpt
Sure! It's a simple Doppler calculation.

We have our initial wavelength (low energy X-Ray) at about 6 nm and a visible wavelength of yellow at about 600 nm.

Using the redshift equations:  
1 + z = 600 / 6  
z = 99 (This is our redshift index)

So for an object moving directly away from us, that gives a speed of:  
1 + z = 1/sqrt(1-b^(2))  
100 = 1/sqrt(1-b^(2))  
b = .99995

So that x-ray emitter would have to be moving away from us at 99.995% of the speed of light. Which is pretty fast.