I was playing around in Space Engine recently, and I realized I hadn't yet landed on a neutron star. This seemed like a very sensible thing to do, so I did it and chose a (relatively) well-known one called Black Widow on which to conduct my adventure. As I landed, I saw mostly expected things-it bent space-time, was rotating very fast, etc. One thing I didn't expect, however, was that everything was blue. Everything. I don't mean the star itself appeared blue, I mean as I looked off the star into the galaxy all the stars appeared blue. I searched for a while but didn't find anything on the Internet. Anyways, does anyone here know why this is happening?

Edit: I have a theory —probably wrong— but maybe because of the warping of spacetime near the neutron star, photons are getting compressed and blueshifted.

  • $\begingroup$ A fun fact is that on the surface of a neutron star, it should look like the bottom of a well or deep valley. You get the blue shift and you also get the curving of light. While the surface of a neutron star is quite spherical and what we would call "flat" the light is bent in such a way as to look like you're in the bottom of a well or deep valley. $\endgroup$
    – userLTK
    Nov 3, 2020 at 9:00

1 Answer 1


Your suspicion is right, the term is gravitational blueshift.

Going down a gravity well, photons gain energy, pushing their wavelengths in the blue direction. The opposite would be gravitational redshift observed when photons climb out of a gravity well.

In terms of general relativity, when you observe the world from near the neutron star, time appears to go faster outside the gravity well, and therefore arriving wavelengths are blueshifted.


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