# Planet/moon most inhospitable to humans? **URL:** \ **Category:** Factual Questions\ **Created:** [January 19, 2011, 7:48am UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184 "2011-01-19T07:48:49Z")\ **Posts on this page:** 16\ **Page:** 2
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [January 19, 2011, 6:36pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/21 "2011-01-19T18:36:34Z")
Yes, that would be better. Earth might be considered the most inhospitable. ---
**Author:** ![Mr.Kobayashi](https://avatars.discourse-cdn.com/v4/letter/m/4af34b/32.png) [@Mr.Kobayashi](https://boards.straightdope.com/u/Mr.Kobayashi)\ **Post date:** [January 19, 2011, 6:44pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/22 "2011-01-19T18:44:34Z")
I took ‘inhospitable’ to mean - “the environmental condition in a region that lacks a favorable climate or terrain for life or growth” - so if you’re instantly vaporised, that’s pretty damn unfavourable to life! ---
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [January 19, 2011, 6:50pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/23 "2011-01-19T18:50:51Z")
> [@Mr.Kobayashi](#): > > I took ‘inhospitable’ to mean - “the environmental condition in a region that lacks a favorable climate or terrain for life or growth” - so if you’re instantly vaporised, that’s pretty damn unfavourable to life! Obviously…but my point was that in most cases you would be vaporized, almost instantly, the only variable being how fast that would occur. If you’re question had been “On what planet/moon would you survive the longest before the atmospheric conditions killed you” then we could contrast and compare. Also, whatever said human is wearing would have minimal effect. ---
**Author:** ![Mr.Kobayashi](https://avatars.discourse-cdn.com/v4/letter/m/4af34b/32.png) [@Mr.Kobayashi](https://boards.straightdope.com/u/Mr.Kobayashi)\ **Post date:** [January 19, 2011, 7:41pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/24 "2011-01-19T19:41:18Z")
Whatever, you got the gist of it. ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [January 19, 2011, 7:54pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/25 "2011-01-19T19:54:12Z")
I think only a very few have any chance of vaporizing you. More common would be asphyxiation, freezing, and/or being crushed into a very solid chunk of ex-human. Vaporization would require high heat and relatively low pressure, which isn’t really all that common outside of the solar corona. ---
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [January 19, 2011, 8:08pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/26 "2011-01-19T20:08:34Z")
I stand corrected, after review, the temperatures were not as extreme as I had anticipated. The pressures at “surface” levels are much more impressive. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 19, 2011, 9:24pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/27 "2011-01-19T21:24:59Z")
> [@Alka\_Seltzer](#): > > …and jets from Quasars which are effectively death rays tens of thousands of light years long. Yeah…except Quasars do not exist anymore in our universe. That said if you were near one getting hosed down by it would pretty much suck (IIRC they had the energy output of a galaxy). (Actually come to think of it I am guessing it wouldn’t suck much beyond being dead…you’d be vaporized so fast I doubt you’d even know you died.) ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [January 19, 2011, 10:16pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/28 "2011-01-19T22:16:00Z")
> [@Whack-a-Mole](#): > > Yeah…except Quasars do not exist anymore in our universe. I don’t think we know that for sure, we can’t see the current state of most of the universe as the light hasn’t had time to reach us. From the wiki article on Quasars: > [@](#): > > Quasars may also be ignited or re-ignited from normal galaxies when infused with a fresh source of matter. In fact, it has been theorized that a quasar could form as the Andromeda galaxy collides with our own Milky Way galaxy in approximately 3–5 billion years. Here’s a picture of a [5000 light-year long jet](http://en.wikipedia.org/wiki/File:M87_jet.jpg) from a active galaxy M87, which is only 53 millions light years away. That’s the same mechanism that powers quasars but on a smaller scale, relatively recently. You certainly wouldn’t want to be in it’s path. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 19, 2011, 10:25pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/29 "2011-01-19T22:25:13Z")
> [@Alka\_Seltzer](#): > > I don’t think we know that for sure, we can’t see the current state of most of the universe as the light hasn’t had time to reach us. They aren’t there because it stems from the [Cosmological Principle](http://en.wikipedia.org/wiki/Cosmological_principle) (simply stated that the Earth does not hold a special position in the universe and on large scale the universe is roughly the same in all directions). That being the case the only reason we see quasars very distant from us is because they are a feature of a younger universe. The nearest quasar to us is 2.5 billion light years away. If quasars were a regular feature of the universe we should see some closer but we don’t. If you could magic yourself out to where a quasar is you’d probably see quasars close(ish) to the Milky Way and none near you. In short, the universe would look the same from there as it would from here and you’d only see quasars very distant to you. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [January 19, 2011, 10:41pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/30 "2011-01-19T22:41:05Z")
> [@Enderw24](#): > > Nitpicky: Mercury rotates. Larry Niven got it wrong, however, he knew that. The problem was that the discovery was made literally between the time he wrote the story and the time when it was accepted for publication. Bad luck for him. He requested from the editor the chance to revise his story but they said it wasn’t necessary. _The Coldest Place_, yes. But the “superconducting brain” story, _Wait It Out_, is set on Pluto (as you doubtless know). ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [January 19, 2011, 10:48pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/31 "2011-01-19T22:48:21Z")
I know this doesn’t qualify, but I just spent the morning reading up on some real world astronomy. From the wiki article on Rigel, the brightest star in the Orion constellation: > [@](#): > > The star is so bright that when at 1 astronomical unit from the star, it shines as an extremely bright ball with an angular diameter of 35° with magnitude -38. The power flux is 100 MW / m2 or 10 kW / cm2, compared to the Sun’s flux of 1.4 kW / m2. The power flux at this distance is the same as the flux a few millimeters from a welding arc; any object this close will be vaporized and blown away by the strong stellar wind. > **[Rigel](https://en.wikipedia.org/wiki/Rigel)** > > Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive component – and the eponym – of a star system of at least four stars that appear as a single blue-white point of light to the naked eye. This system is located at a distance of approximately 850 light-years (260 pc). > A star of spectral type B8Ia, Rigel is calculated to be anywhere fro... ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [January 19, 2011, 10:51pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/32 "2011-01-19T22:51:24Z")
> [@Alka\_Seltzer](#): > > I don’t think we know that for sure, we can’t see the current state of most of the universe as the light hasn’t had time to reach us. From the wiki article on Quasars: > > Here’s a picture of a [5000 light-year long jet](http://en.wikipedia.org/wiki/File:M87_jet.jpg) from a active galaxy M87, which is only 53 millions light years away. That’s the same mechanism that powers quasars but on a smaller scale, relatively recently. You certainly wouldn’t want to be in it’s path. Such as in the case of the “[Death Star galaxy](http://news.nationalgeographic.com/news/2007/12/071217-black-holes.html)”, where such a jet is actually bombarding a nearby neighbor. > [@](#): > > The images show a jet reaching out like a tentacle from the larger galaxy—which is about the size of the Milky Way—about a million light-years into space. About 20,000 light-years along the way, the jet encounters the smaller galaxy. > > That galaxy—which is also thought to harbor a supermassive black hole—has swung itself into the path of the jet and is rotating clockwise toward it. > > \ > > The newfound jet isn’t as bright as our sun, but it is putting out enormous amounts of powerful gamma rays and x-rays, study author Evans said. That’s bad news for any nearby planets. > > “Ozone would be destroyed in months,” he said. “This could possibly lead to the destruction of most forms of life.” ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [January 20, 2011, 9:36am UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/33 "2011-01-20T09:36:19Z")
> [@Whack-a-Mole](#): > > That being the case the only reason we see quasars very distant from us is because they are a feature of a younger universe. The nearest quasar to us is 2.5 billion light years away. If quasars were a regular feature of the universe we should see some closer but we don’t. Quasars can turn on and off, depending on how much material they are accreting. Just because the nearest quasar we can see is 2.5 billion light years away does not mean that there has been no quasar activity since then. Quasars were certainly much more common in the early universe, but that doesn’t mean future quasar activity is impossible. Some models predict a quasars can form as a result of galaxies merging. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 20, 2011, 10:36am UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/34 "2011-01-20T10:36:50Z")
> [@Alka\_Seltzer](#): > > Quasars can turn on and off, depending on how much material they are accreting. Just because the nearest quasar we can see is 2.5 billion light years away does not mean that there has been no quasar activity since then. Quasars were certainly much more common in the early universe, but that doesn’t mean future quasar activity is impossible. Some models predict a quasars can form as a result of galaxies merging. Perhaps so but reference the Cosmological Principle again. It may be possible (I have no idea) but we see nothing like that and no matter where you are in the universe it should look about the same as it does from here. _If_ a quasar could appear “near” us (say less than 100 million light years) all I can say is such a thing is apparently super-unlikely. ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [January 20, 2011, 11:24am UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/35 "2011-01-20T11:24:42Z")
Yes, but we’re only seeing a snapshot of the current state of the universe, we’ve only been observing seriously for a few decades. Your argument supports the conclusions that quasars were much more common in the early universe, and are now very rare. Over time, more gas ends up either in stars or in supermassive black holes. But that doesn’t mean that quasars are extinct yet. The only difference between an AGN and a quasar is the rate of accretion. M87 is estimated to accrete about a tenth of a solar mass of material a year, compared to about ten solar masses for a typical quasar. That’s a factor of 100. It’s not a huge stretch to imagine that it might reach those levels, or close to those levels, at some stage of a galactic merger. Anyway, Der Tris’ link above shows that death rays in the thousand light-year long class are still in existence. ---
**Author:** ![foolsguinea](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foolsguinea/32/14751_2.png) [@foolsguinea](https://boards.straightdope.com/u/foolsguinea)\ **Post date:** [January 20, 2011, 12:03pm UTC](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184/36 "2011-01-20T12:03:04Z")
> [@Whack-a-Mole](#): > > Perhaps so but reference the Cosmological Principle again. Alternatively, the Anthropic Principle implies that we exist in a region that allows us to exist. We may have had the chance to evolve because our section of space is particularly unlikely to develop quasars. [Previous page](https://boards.straightdope.com/t/planet-moon-most-inhospitable-to-humans/568184.md?page=1)