system
Given the following post, respond as if you're commenting on Reddit:
human
What colour are Neutron stars?

Assuming we have a magic shield that blocks out all non-visible light, and a human eye (human optional) within viewing distance, what colour would a neutron star appear to be?

Would there be a shift in spectrum emissions because of gravitational effects?
gpt
**Short answer:** White. Neutron stars are simply white hot. 

**Long answer:** Surface temperature of a neutron star is in the neighborhood of 1 million K. This has a peak blackbody spectra around a few nanometers, well below the 400 nm or so cutoff of the visible spectra. The visible spectra is just going to be an enormous blindingly bright wall of mixed light. 

If you put on really really really thick sunglasses, you should be able to see the preference for blue. And even though the light will be redshifted by about 25%, that shouldn't really effect the spectra you see all that much. For every photon that's redshifted out of the range of human sight, another will be redshifted in from the ultraviolet, so it should more or less look the same, whether or not you consider general relativistic effects. 

If you wait many many many billions (trillions?) of years, they'll eventually cool to a few thousand Kelvin, and their black body curve will begin to peak in the visible spectra, so the white/blue hotness will fade to a red hotness, before eventually they turn black with the heat death of the universe.