Considering a cold planet , very cold one, would an environmental suit be specifically needed for such an environment or a spaceuit would be enough? Considering the planet has an atmosphere to transfer heat etc...

Or is the reverse? The Space would need a better suit to protect from cold?

And what about the reverse for hot environments and space in direct radiation from the star?

  • $\begingroup$ Cold is essentially the absence of heat...so it completely depends on how far away it is from a heat source... $\endgroup$ – A.bakker Mar 12 at 14:33
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    $\begingroup$ You seem to be mixing up two different things: temperature and heat exchange rate. Do you mind clarifying? $\endgroup$ – L.Dutch - Reinstate Monica Mar 12 at 14:41
  • $\begingroup$ In the vacuum of space, your side which is exposed to the Sun will be cooked, and the side away from the Sun will freeze. On the Moon, which has no air, surface temperatures range from −280 °F (−170 °C) in night time to +260 °F (−130 °C) in day time. $\endgroup$ – AlexP Mar 12 at 15:16
  • $\begingroup$ Is there a world building question here? This seems like it's off topic. $\endgroup$ – puppetsock Mar 12 at 15:35
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    $\begingroup$ I'm voting to close this question as off-topic because it seems to be asking a question of simple fact, not building a world. $\endgroup$ – puppetsock Mar 12 at 15:37

The cold planet will need more protection.

The vacuum of space is actually a near perfect insulator for all heat transfer except radiative heat transfer, and to protect against radiative transfer, all the suit would need is a reflective surface to reduce the heat transfer rate.

Note that this assumes that the low pressure problem is already solved and that nothing is going to be evaporating (like the water in your blood) due to being subject to a vacuum.

This is also true for the hot environmental case.

The practical upshot is that when you're in space all that you need to worry about is radiative heat transfer, when you're on a planet you still need to worry about radiative heat, as well as conductive and convective heat transfer.

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Your typical NASA EVA Suit is made from 11 layers of highly insulating material, but insulation from cold is not the point. They have to be insulated to protect you from intense solar radiation which is about twice as energetic in space as it is in the Earth's atmosphere. Because they are so well designed to prevent heat from getting in when faced with direct sunlight, they are equally good at preventing heat from getting out. They are so effective that even in the Earth's shadow where space in nearly absolute zero, they need to rely on internal cooling systems to keep your own body heat from cooking you over time.

In an atmosphere, cold feels colder and hot feels hotter as Mathadditcs answer explains, but you also have a lot more normalizing factors; so, where the orbital distance is the same, a person on a planet with an atmosphere will experience much less severe fluctuations in temperature than the one in a vacuum, especially on a planet that is not tidally locked to the sun. So, how hot or cold you feel would be more similar than the numbers suggest.

I can't find any details on the coldest atmospheric conditions a space suit can theoretically be used in, but Concordia station in Antarctica has been used as a terrestrial analogue site where EVA suits endure in atmosphere conditions of −82 to −48 °C. So, I can not tell you if a standard EVA suit would do well on a REALLY cold world, but it's probably better than just about any other cold weather gear you might conceivably have access to.

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