# If the sun goes out... **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [June 17, 2016, 12:03pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596 "2016-06-17T12:03:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![psythe](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@psythe](https://boards.straightdope.com/u/psythe)\ **Post date:** [June 17, 2016, 12:03pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/1 "2016-06-17T12:03:18Z")
[Original link](http://www.straightdope.com/columns/read/3293/if-the-sun-goes-out-how-long-till-the-earth-freezes?utm_campaign=1348218_The%20Straight%20Dope%3A%2006%2F17%2F2016&utm_medium=email&utm_source=ChicagoReader&dm_i=2JCR,SWAI,2KTGVB,22DQZ,1) Cecil, my understanding is that if the Sun was replaced by a black hole\*, the lack of heat in fact _would_ be our biggest concern. Black holes are merely objects which have been compressed to a sufficient density that the gravity at their surface (or I suppose, at a point above their surface) exceeds the speed of light (or to put it another way, you’d need to go so fast to escape them that the relativistic mass increase you’d experience in the process would increase the force of gravity upon you to the extent that it would compensate for your increased speed). The point is that even the Earth could be turned into a black hole (if you crushed it into a ball a few cm in diameter). If that happened, the moon would still experience the same gravitational pull (which is based on total mass and distance, neither of which has changed). For that matter, if the moon got turned into a black hole we’d still get lunar tides etc on Earth. \*Of equivalent mass. No wriggling off the hook by replacing it with a supermassive black hole now! [sits back and waits to be crucified] ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [June 17, 2016, 2:06pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/2 "2016-06-17T14:06:20Z")
FWIW, my reading of Unka Cec’s column is that he handwaved the whole “sun goes out” thing and just tackled the effects on Earth, rather that “how it started.” In other words, “how” is an interesting tangent, but not the meat of the question. FWIW, if the Sun were swallowed up by a BH with an event horizon large enough to eradicate the Sun instantaneously\*, we’d be in a serious sack of trouble (or already gone), because a Schwarzschild radius of solar radius (i.e., big enough to eat the Sun at one gulp) requires a singularity of 235,000 solar masses. And that much mass will have monstrous effects in its neighborhood. \*Has to be instantaneous, or else the Sun would “go out” slowly or do something more radical than “the lights go out”. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 17, 2016, 2:17pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/3 "2016-06-17T14:17:35Z")
I’ll start the nail-driving the OP asked for. Not exactly clear why **The Master** is so dismissive of the primary source for this material, but activity over the speed of light is extremely well referenced beyond Disney Labs. Consider: _Star Trek_, all flavors _Chronicles of Pern_, all flavors _The Coming of the Quantum Cats_ _Dune_, all flavors _Dave Berry’s How to Manage Money_ So, the presumption that nothing goes faster than light is readily dismissed, or it’s just not Science Fiction or your bank’s service charges. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [June 17, 2016, 2:35pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/4 "2016-06-17T14:35:44Z")
I just remembered another sci-fi setting in which the sun “goes out”. Vernor Vinge’s _Deepness in the Sky_. The fictional On-Off Star is an astrophysical oddity: it has a 250-year cycle in which it shines as a normal G-class star for 35 years, and then becomes a cool brown dwarf for the remaining 215 years. There is one planet, in the Goldilocks zone (during the warm periods). And it has life, including intelligent non-humanoid life. Everything on the planet is adapted to cryogenic cybernation during the dark times. The civilization of the sapients on the planet even continues abated, because their architecture and engineering is designed to survive the freeze and thaw periods. It’s one continuous climb of technological and sociological advancement, except it’s in single-generation chunks separated by centuries of hibernation. Vinge describes how the freeze looks: planet-sized weather systems driven by freezing or thawing water vapor, air snow, floods and flash-thaws at the beginning of the bright times. Very cool, IMHO. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 17, 2016, 4:56pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/5 "2016-06-17T16:56:23Z")
Why is it wrong to consider Earth’s black body temperature of 255 K ? All plants die, flooding the atmosphere with CO[sub]2[/sub] … just saying … ---
**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:** [June 17, 2016, 5:20pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/6 "2016-06-17T17:20:04Z")
Life on earth has little chance of surviving just from the lack of radiation from the sun. In less than a year there won’t be any food left. We won’t be able to grow enough plants with artificial light to feed enough people to keep those lights on for very long. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 17, 2016, 7:06pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/7 "2016-06-17T19:06:06Z")
Cecil mentions the point at which carbon dioxide freezes out of the atmosphere. I presume he means when the temperature reaches the standard freezing point of CO2. But what about vapor pressure? Water evaporates despite the fact that the temperature is lower than 100 C because at room temperature the vapor pressure of water usually exceeds the partial pressure of the water vapor in the air. Same thing with carbon dioxide: At 400 ppm I presume the partial pressure is pretty low; how cold would it have to be before more CO2 would condense than sublimate? The liquefaction of the air presents a similar problem: as oxygen started to condense, the pressure of the air would drop and thus it would take still colder temperatures to get any more to condense. So I think it would be a rather more complex situation than having all the air simply rain down. ---
**Author:** ![psythe](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@psythe](https://boards.straightdope.com/u/psythe)\ **Post date:** [June 18, 2016, 1:35pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/8 "2016-06-18T13:35:21Z")
> [@gnoitall](#): > > I just remembered another sci-fi setting in which the sun “goes out”. Vernor Vinge’s _Deepness in the Sky_. Cool idea indeed - but you wouldn’t need an on-off star for that setting, just a planet with a significantly elliptical orbit. I suppose you would get different tidal forces, but with everything frozen most of the time I’m not sure how relevant it would be. ---
**Author:** ![psythe](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@psythe](https://boards.straightdope.com/u/psythe)\ **Post date:** [June 18, 2016, 1:49pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/9 "2016-06-18T13:49:22Z")
> [@Lumpy](#): > > At 400 ppm I presume the partial pressure is pretty low; how cold would it have to be before more CO2 would condense than sublimate?. I’m a little out of my comfort zone here, but my understanding is that, at least as far as water is concerned, warm air holds more water than cold air does. Another thought occurs to me though - the majority of air pressure is made from nitrogen rather than carbon dioxide, and the boiling point of that is considerably lower than the sublimation point of CO2, so the CO2 could come out of the atmosphere completely without it doing much to the pressure at the planet’s surface\*. \*changing the temperature would alter atmospheric pressure/volume via Boyle’s law, but I imagine it is the volume which would change rather than the pressure. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 18, 2016, 5:53pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/10 "2016-06-18T17:53:55Z")
There’s a limit to how much water vapor the air can hold, that amount depends on temperature and pressure. As temperature goes down, the extra water will condense and fall as rain. Carbon dioxide will deposit directly into it’s solid phase and snow down at 195 K. Oxygen condenses at 90 K (freezes at 55 K) … and when it does that will reduce pressure a good amount … not sure if Nitrogen will condense at 77 K (freezes at 63 K) at 0.8 atmospheres pressure. At 44 K given in the article, almost all the atmosphere is frozen, the top layer of the “ice” would be Oxygen. Argon condenses at 87 K, freezes at 84 K, and about 1% of the atmosphere. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [June 19, 2016, 5:33am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/11 "2016-06-19T05:33:31Z")
> [@watchwolf49](#): > > Why is it wrong to consider Earth’s black body temperature of 255 K ? It’s not actually at that temperature right now. Greenhouse gases increase the Earth’s average temperature to about 288 K. But with the Sun going out, it won’t stay that warm for long. > [@](#): > > All plants die, flooding the atmosphere with CO[sub]2[/sub] … just saying … The plants are freezing, not burning, so they won’t release their CO[sub]2[/sub]. And adding more CO[sub]2[/sub] to the atmosphere in that situation will only slow the cooling by a small amount anyway. Cecil mentions Fritz Lieber’s “A Pail of Air”, which is a good story, no question. But don’t take it as what it might be like if the Earth were grabbed away from the Sun by a Dark Star™. There’s holes in that story you could drive a rogue planet through. ---
**Author:** ![Simon\_Bone](https://avatars.discourse-cdn.com/v4/letter/s/d2c977/32.png) [@Simon\_Bone](https://boards.straightdope.com/u/Simon_Bone)\ **Post date:** [June 19, 2016, 9:02am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/12 "2016-06-19T09:02:06Z")
Hate to nitpick Cecil… but “degrees Kelvin”? He knows better than that. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [June 19, 2016, 11:37am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/13 "2016-06-19T11:37:14Z")
A letter to Nature by David Stevenson on the subject of life-sustaining planets in deep space, with ecologies supported by geothermal energy. [https://www.researchgate.net/publication/12896573\_Life-sustaining\_planets\_in\_interstellar\_space](https://www.researchgate.net/publication/12896573_Life-sustaining_planets_in_interstellar_space) If there are substantial numbers of Earth-sized planets in interstellar space (which seems entirely possible) then this sort of planet might be the most common location for life in the universe. Liquid water could exist under layers of frozen gases and water ice. Note that the surface of Pluto is surprisingly active for such a cold world; there could be many surprises waiting out there on deep space objects. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [June 19, 2016, 11:59am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/14 "2016-06-19T11:59:19Z")
> [@dtilque](#): > > The plants are freezing, not burning, so they won’t release their CO[sub]2[/sub]. Maybe they would, and rather dramatically so, when drenched in liquid oxygen? But I guess they would be mostly protected under metres of snow by then. What about LOx seeping into oil wells and coal mines? Could we expect some fireworks there? ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 19, 2016, 3:33pm UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/15 "2016-06-19T15:33:10Z")
> [@dtilque](#): > > It’s not actually at that temperature right now. Greenhouse gases increase the Earth’s average temperature to about 288 K. But with the Sun going out, it won’t stay that warm for long. The 255 K is the temperature of the Earth with only her own internal energy (and idealizing the system as a perfect black body). The solid rocks on the surface is just a thin crust over layers of increasing liquid rock. All that energy is radiating out into space. Solar energy has nothing to do with that, and the energy the sun adds is what brings up to the 288 K. > [@dtilque](#): > > The plants are freezing, not burning, so they won’t release their CO[sub]2[/sub]. And adding more CO[sub]2[/sub] to the atmosphere in that situation will only slow the cooling by a small amount anyway … [snip] No, plants require sunlight, or they die rather quickly. Anyone who grows marijuana in their closet knows a couple days power outage and their crop is gone; dead, brown and withered. Couple more days and the plant material will dry out, add several billion people using torches for light and I think we’ll see all that carbon converted to CO[sub]2[/sub] in a week or two. > [@Simon\_Bone](#): > > Hate to nitpick Cecil… but “degrees Kelvin”? He knows better than that. Forgive **The Master** his ancient of years … “degrees Kelvin” was proper up until 1968 … bonus nitpick, properly it’s kelvin (with a lower case k) and abbreviated with a capital K (no degrees) AND it’s proper plural is kelvins {[Cite](http://physics.stackexchange.com/questions/114079/are-there-reasons-for-the-discrepancies-in-absolute-temp-units-kelvin-vs-kelv)}. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [June 20, 2016, 2:36am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/16 "2016-06-20T02:36:36Z")
> [@watchwolf49](#): > > The 255 K is the temperature of the Earth with only her own internal energy (and idealizing the system as a perfect black body). The solid rocks on the surface is just a thin crust over layers of increasing liquid rock. All that energy is radiating out into space. Solar energy has nothing to do with that, and the energy the sun adds is what brings up to the 288 K. Don’t think so. From [here](http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html) > [@](#): > > This effective temperature of 255 K is the temperature the Earth’s Surface would have if it didn’t have an atmosphere. It would be awfully cold! In reality, the Earth’s surface temperature is closer to 288 K (15 °C, 59 °F). This difference of 33 K is the magnitude of the greenhouse effect. Note that these calculations are of the Earth’s blackbody temp due to incident sunlight. The internal heat of the Earth did not come into the calcs at all. That isn’t the only site with those calculations on the net, by the way. > [@](#): > > No, plants require sunlight, or they die rather quickly. And as someone else pointed out, they’ll be covered in snow (also probably ice). Besides that, you need more than just fuel and oxygen to get a fire. You also need heat or a spark or something. Those are going to be in short supply when the atmospheric temperature is that low (low enough to liquify oxygen). ---
**Author:** ![david\_42](https://avatars.discourse-cdn.com/v4/letter/d/cc9497/32.png) [@david\_42](https://boards.straightdope.com/u/david_42)\ **Post date:** [June 20, 2016, 2:37am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/17 "2016-06-20T02:37:16Z")
Thanks for the reminder about ‘A Bucket of Air’, takes me back about 6 decades. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 20, 2016, 3:27am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/18 "2016-06-20T03:27:18Z")
> [@dtilque](#): > > Don’t think so. From [here](http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html) … [snip] That’s a very good reason not to use 255 K, thanks. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [June 20, 2016, 4:09am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/19 "2016-06-20T04:09:43Z")
> [@dtilque](#): > > Don’t think so. From [here](http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html) > > And as someone else pointed out, they’ll be covered in snow (also probably ice).\*\* Besides that, you need more than just fuel and oxygen to get a fire. You also need heat or a spark or something.\*\* Those are going to be in short supply when the atmospheric temperature is that low (low enough to liquify oxygen). It wouldn’t take much of a spark, though – from what I gather, a mixture of liquid oxygen and charcoal is about as sensitive (and explosive!) as nitroglycerin…! I believe some hydrocarbons are notoriously prone to spontaneous ignition when mixed with liquid oxygen. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 20, 2016, 5:15am UTC](https://boards.straightdope.com/t/if-the-sun-goes-out/757596/20 "2016-06-20T05:15:06Z")
> [@Ignotus](#): > > It wouldn’t take much of a spark, though – from what I gather, a mixture of liquid oxygen and charcoal is about as sensitive (and explosive!) as nitroglycerin…! > > I believe some hydrocarbons are notoriously prone to spontaneous ignition when mixed with liquid oxygen. We have 38 days until we freeze; plants are dead, dry and torched in 14 days, tops. Year and a half until the oxygen rains down … plenty of time for the abandoned oil wells to gush out serious amounts of hydrocarbons. Life would continue around sea floor vents, and evolve to exploit the new niches created … so nothing to worry about eh? [Next page](https://boards.straightdope.com/t/if-the-sun-goes-out/757596.md?page=2)