The subject of the perception of colors has many facets- the psychological aspects, the physiological aspects, the physical aspects, among others.
Color is an interesting and complex subject.
Also, in your question, you are talking as if the Sun is appearing orange in color. I'm assuming that you are seeing it with your naked eye, such as a setting Sun, low on the horizon, rather than seeing the Sun through an orange filter. Color is in your head. The physics of colors is the following. The colors that we see depends on the frequency of the emitted light.