In that case (Destiny)

by roland , Tuesday, July 01, 2014, 17:13 (3797 days ago) @ ZackDark

What sort of gases would be able to filter our sun's light into blue?

Earth's atmosphere preferentially scatters blue light through a process called Raleigh scattering. The color of the sky (on any planet) is mostly dependent upon the size of the molecules that make up the atmosphere as well as how thick the atmosphere is. On Earth at sunset the sky looks more red because light from the Sun has to travel through significantly more air to get to us, and the blue light is scattered so much along the way that it becomes so diffuse we can't see it anymore. Mars, on the other hand, has a lot of dust in the atmosphere which increases the average size of the particles in the air, so the scattered light is shifted a bit to the red. But there's also a whole lot less air on Mars to scatter light from the Sun, so the true color of the sky is reddish-grayish-blueish. This is approximate true color.

Interestingly, sulfate particles have been demonstrated on Earth to turn the sky even brighter blue. So perhaps the increased volcanism on Venus would explain the bluer sky on a hypothetical post-Traveler "jungly" Venus.