It's not something as drastic as those suggestions, littleprince. If Zoltar is observing Betelgeuse around 10-11pm local time, the star is close to the horizon. The starlight has more atmosphere to travel through than when viewed closer to the zenith. Our atmosphere scatters shorter wavelengths, and the object looks 'redder'. The same thing happens to the Sun around sunset.
I am glad that you are taking an astro course. Keeps people like me employed.