Terminator Too

While still on the topic of the Earth's terminator, let's talk about another of its distinct feature - the red color due to atmospheric Rayleigh scattering. From the surface, we experience the reddening as sunrise and sunsets. Here's a reference photo of the Earth's terminator taken from the ISS on 12 Apr 2011:

Sunset over Western South America (source: NASA)

Clearly a photorealistic CG Earth would need to replicate this feature. The following are test images dated 11-16 Oct 2011:

A tell-tale sign that an Earth image is CG - no reddening at the terminator line

Sunset colors at the terminator line, but still poorly implemented and highly unconvincing ^^;;

A higher resolution, tone-mapped work-in-progress shot of the terminator reddening