>>9934708As a primer for this, I'm well aware there's much more nuance to solar radiation, greenhouse affect, albedo, etc. I'm out of my depth and likely to make mistakes. I did want to get some discussion going though, and see if people corrected me, because it would be interesting.
I'm working "base" temperature out here using:
>255/(a/L^0.5)^0.5Where 'a' is the semimajor axis and L is stellar luminosity. For ease here I just measured in AU and solar luminosities.
In Venus' current orbit, at 0.72 AU, using above I figured out it would have a "base" temperature of 300 K (27 C), in comparison to Earth's 255 K (-18 C).
Now I'd add for a greenhouse effect. Earth's greenhouse affect is about 33 K. I could say the same for Venus, if it had an Earth-like atmosphere, but I assume it would be larger as the observed luminosity would be brighter.
So, using square cube, I figured it would be 93% brighter. So, I gave a greenhouse of 64 K (approx. 33 * 1.93). Adding to the 300 K base, that would give Venus with Earth's atmosphere something like 364 K average on the surface (91 C).
I'm aware albedo, rotation period, and atmosphere mass will probably play into it more, but this is an estimate, feel free to add to it.
With trial and error, I also found a place for Venus where with it's present atmosphere it may have Earth like temperatures, using much the same means as before. At 2 AU, it would have it's "base" temperature of about 180 K. Normally with a temperature of 300 K, and a greenhouse effect of 437 K, it reaches 737 K (464 C). At 2 AU, with the square cube law I can assume that the solar luminosity appears 4 times dimmer. So, with 180 K, I'll add 109 K as the greenhouse effect for its atmosphere (437 / 4). That would give us 289 K (16 C).
Both are thoroughly implausible, and not even very useful for habitation/terraforming, but I thought the info might be useful. If I'm wrong or pulling methods out my ass, let me know.
