I’m trying to get a sense of how bright the surface of Venus would appear in the visible wavelengths to a hypothetical human astronaut in an unobtanium pressure suit. Venus is significantly closer to the Sun, but has much (!) thicker cloud cover. Google searches on the topic tend to address Venus’ albedo, which isn’t what I’m interested in. There are some low-quality search engine hits that suggest anything from ‘dark’ to ‘like a foggy noon on Earth’. For the sake of the hypothetical, let’s assume we’re talking local noon on the Venusian equator on the summer solstice and go from there.
Ideally I’d like some published research on the matter, but I seem to be missing the correct terms of art to get the results I am looking for. Any advice? I did encounter one paper that noted that the surface illumination would be omnidirectional, resulting in no significant shadows, making it difficult to distinguish surface features - like skiing on an overcast day, perhaps.
Here you go: https://www.jstor.org/stable/1738337
Looks like about 1 W/m^2 is transmitted through the atmosphere; on the other hand you have all the scattered light.
Just curious, why did you pick the solstice? The noon sun at the equator is at its lowest on the solstices. If you wanted the sun to be vertically overhead, as high as it possibly can get, that happens at noon at the equator on the equinoxes.
Venus’ axial tilt is only 2.64 degrees, so the amount of lighting is not going to vary much throughout its year. The variation in lighting at the equator will probably not be noticeable by the hypothetical humans that visit.
I read a pop science article a long time ago that made the claim that it’s never completely dark anywhere on Venus’s surface. Its atmosphere is so dense it refracts light all the way around to the antisolar point. At local midnight, one would see the Sun collapsed into a long thin line along the horizon. I was unable to google anything today confirming that; every likely hit turned out to just talk about the unusually long Venusian day.