From Gerald Vanderleun: two worlds, one sun:
Martian sunset
yes, for reasons not completely understood, the red planet has blue sunsets
Earth sunset
the blue planet has red sunsets
The sun appears a bit smaller on Mars, because it is 50% further away. That means it receives just 25% of the energy, and since it has much less atmosphere, it retains a lot less of it.
I can't stop looking at the top picture; it is so weird to realize that really exists, it isn't just a scene from a movie...
| 
