Without an atmosphere in space, how close would you actually have to get to the sun before it would be hot enough to kill you (from the heat, not just radiation)
In: Physics
This isn’t really a very straight forward question. For the most part, as long as there isn’t junk in between you and our sun, your blood could still boil right outside Earth’s atmosphere. If there’s anything between you and the sun that can block direct sunlight from hitting you, you’ll start to freeze to death fairly quickly.
I seem to recall an estimate saying a human with a perfect spacesuit could survive comfortably around twice the distance from the Earth, so around 300 billion meters (186,000,000 miles), given the rough volume of a human and a rough estimate of surface area absorbing heat. But that all depends on the space around you.
People die from the sun’s heat right here on Earth. Also from radiation by getting skin cancer.
In this case, all the heat being imparted on to you is going to come from radiation. That is, until you hit the atmosphere of the sun, at which point you’re going to basically be vaporised instantly, so I suppose the answer is a couple thousand feet into the atmosphere of the sun.
The Sun can get hot enough to kill you right here on Earth.
Cooling is one of the major challenges of working in Earth orbit. The ISS has huge cooling panels and a very beefy refrigeration system just to keep the astronauts from being slow-cooked every time it’s in direct sunlight.
Right here is fine. I think on the moon it’s like 250*f in the sun shine… I did not fact check
Without active cooling, space around earth is sufficiently “hot” to kill you.
Light intensity at Earth-distance is 1360 W/m^2. To radiate the same amount of heat (per area), your body would have to be at 120°C*.
Your shape works in your favor here, since usually inly half your body is in the sun – this brings the temperature down to a crispy 57°C – still enough to kill you reliably.
Around Mars, you would get a chilly -5°C, which after factoring in the ~100W your body produces would most likely result in a nice temp.
This is all calculated for the worst case where the front of your body is oriented towards the sun. You could minimize the part of your surface thats exposed to sunlight (e.g. point your feet towards the sun) to reduce your temperature.
*According to [Boltzmanns Law](https://en.m.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law)
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