Q:

Why aren’t sunsets red when viewed from low earth orbit?

So “Why are sunsets red?” seems to be a pretty common question and it has to do with Rayleigh scattering in the atmosphere. I’m following some game dev tutorials (example implementation) on how to model and simulate this effect in computer graphics with the relevant scattering equations.
Every model has a strong red tinge near the terminator, especially when viewed from the night side of the earth, looking towards the sun, much like how sunsets look from the ground.

Yet, when I look at various NASA images from the ISS, the red color is barely visible at all!

This is the only image I could find that contains even a trace of red coloring.
All atmospheric scattering implementations I have seen use the line integrals from the nvidia article linked earlier. What are they missing?

A:

In ISS, the red phase of sunset, that is the descent of the Sun through the troposphere, lasts only a few seconds. In contrast, the blue crescent of the upper atmosphere is visible for several minutes. Therefore the red phase is missing on many sunset photos from ISS. 

Sunrise at ISS. Source: NASA/Scott Kelly
Similar photo and video

