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The Saturn system is about 10 times as far from the Sun as the Earth. This question is concerning Titan for two reasons: Titan has an Earthlike atmosphere so you don't have to account for a higher radiation due to vacuum. Titan's surface pressure is 1.45 atm (21.5 psi) but imagine you're standing on the summit of a mountain where the pressure were 1 atm (14.7 psi). The 2nd reason is that due to Titan's Earthlike atmosphere you don't need a spacesuit but an oxygen mask and warm clothes only (that should cover your entire body if you don't wanna get frostbites).

Compared to the average UV dose on the surface of the Earth, how much radiation would you get on a mountain peak on Titan? Since Titan is 10 times farther from the Sun, does this mean you get 10 times less the radiation on Earth, or does it decrease with the square so you get a 100 times less radiation of what you get on Earth? Or something else?

Also, do you know a calculator that can determine UV radiation and account for all factors?

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    $\begingroup$ The other factor is that there is no oxygen in Titan's atmosphere, so no ozone layer. But practically, if you have enough exposed skin that sunburn is a issue on Titan, then you have a whole lot of other problems. It's -180 degrees. $\endgroup$ – James K Jul 24 '20 at 6:15
  • $\begingroup$ @JamesK This is why I wrote you should cover your entire body. So no exposed skin. $\endgroup$ – Ioannes Jul 24 '20 at 7:26
  • $\begingroup$ hmm... at almost 6% methane I'll bet almost no UVB (280–315 nm) or UVC (100–280 nm) makes it that far down. $\endgroup$ – uhoh Jul 24 '20 at 11:18
  • $\begingroup$ You are correct that the incident radiation density is 100X less - it's a matter of computing the area of a spherical surface, which goes as the square of the radius. So even in the absence of atmosphere, and assuming you wear some kind of spacesuit that's transparent in the UV, you won't get much of a tan. $\endgroup$ – Carl Witthoft Jul 24 '20 at 16:37
  • $\begingroup$ @CarlWitthoft I see, thank you. That's an actual answer. $\endgroup$ – Ioannes Jul 24 '20 at 16:43
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You are correct that the incident radiation density is 100X less - it's a matter of computing the area of a spherical surface, which goes as the square of the radius. So even in the absence of atmosphere, and assuming you wear some kind of spacesuit that's transparent in the UV, you won't get much of a tan.

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  • $\begingroup$ Perhaps you should remove your comment now. :-) $\endgroup$ – Ioannes Jul 28 '20 at 15:54

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