Doug's Darkworld

War, Science, and Philosophy in a Fractured World.

What Would Happen if the Sun Disappeared?

with 38 comments

For some reason this question gets asked a lot on Yahoo Answers. I’m not sure why, but people seem to be curious about what would happen to Earth if the sun disappeared. The times we live in maybe? Morbid curiosity? I don’t know, it is an odd question. I’ve thought about it a lot, and it is an exercise in science and logic, so here is my best guess as to our fate should the sun mysteriously vanish. As an aside, this isn’t a particularly likely fate for Earth. Stars don’t just go out, so there’s no chance of the sun just turning off. A cloud of some sort of thick interstellar gas could conceivably suddenly blot out the sun, but where such a cloud could suddenly come from defies reason, again, astronomers haven’t noticed any stars in the sky suddenly being blotted out by clouds of gas. So for the sake of argument we are simply going to postulate that in some unknowable way, the Sun simply vanishes one day. What would be our fate?

In short: We’d be hosed. The actual details might be somewhat variable, but it’s still pretty easy to predict. How much does the temperature drop between sunset and sunrise? If the Sun vanishes, it will simply keep dropping at the same rate or an even higher rate as the water freezes out of the atmosphere and Earth loses its cloud cover. At high elevations and arctic areas this means within days the temperature would be several hundred degrees below zero. In the tropics it might take a week or longer, but it’s safe to say that in at most two weeks the entire globe would have cooled to hundreds of degrees below zero, and all surface life as we know it would be impossible. Most humans, as well as most life on the planet, would have frozen to death.

Would the Earth be lifeless? No. The Earth itself would remain warm from radioactive decay for billions of years, so microbes deep in the crust would survive. The oceans would freeze over, but they likely wouldn’t freeze solid. Tidal action, volcanism, and the aforementioned heat from the Earth’s core would likely keep some water liquid. Deep sea life, especially that around sea floor vents that don’t rely on the Sun, would very possibly survive or even thrive.

On the surface though, nada. In fact most of the atmosphere would soon freeze and fall to the earth as snow. Different components would freeze out at different times, so there would be layers of colored snow, methane snow is orange for example. The almost airless sky would be awash with stars, brighter than the starriest night on Earth now. The Moon wouldn’t have phases but it would still be visible as a gray ghost hanging in the cloudless sky, dimly illuminated by starlight. In fact the Earth’s surface would likely be stunningly beautiful in a silent still way, like a frozen dream.

We wouldn’t be around to appreciate it though. Some humans might survive for awhile in deep shelters or nuclear submarines, but unless there were a lot of them in a well equipped base, their chances of long term survival would be almost nil. Still, if there was enough of a society left to support an industrial base, maybe humanity would survive. Nuclear power would last forever, and the entire Earth’s surface would be littered with useful artifacts, not to mention frozen food in one form or another.

Ice skating would be popular. There’d likely be a lot of morbid global warming jokes. The Sun disappearing would certainly put humanity’s current problems in perspective. Conceivably, it might even interfere with the publication of this blog.

(Above image of a 1999 solar eclipse is used legally: Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation license“. Credit and copyright: Luc Viatour. I didn’t even mention what would happen to the rest of the solar system, but if the Sun vanished the solar system’s various planets etc. would simply sail off in all directions. The Earth would keep the Moon and maybe a few captured asteroids as it spun off into deep interstellar space, alone among the stars.)

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Written by unitedcats

July 24, 2008 at 8:47 am

Posted in Science

38 Responses

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  1. Of all the ways the world could end, this isn’t one of them. :)

    Michael

    July 24, 2008 at 10:55 am

  2. I stand corrected:

    Fire and Ice

    Some say the world will end in fire,
    Some say in ice.
    From what I’ve tasted of desire
    I hold with those who favor fire.
    But if it had to perish twice,
    I think I know enough of hate
    To say that for destruction ice
    Is also great
    And would suffice.

    —Robert Frost

    unitedcats

    July 24, 2008 at 7:35 pm

  3. I remember reading a short story many years ago by Fritz Lieber called “A Pail of Air” that addressed this same subject. I remember it being a pretty good read…

    voenixrising

    July 25, 2008 at 6:38 am

  4. Yes, it was a great read. My earliest reading was fifties sci fi stories and they have coloured my life view since, and inspire much I write about in here. Glad there’s still people who appreciate the classics. :)

    unitedcats

    July 25, 2008 at 7:00 am

  5. I came across this post by accident while searching for a solution to a WordPress problem, but I had to take a moment and stop. Considering that you seem to be taking a semi-scientific approach in your post, your info is very poorly conveyed. For example, you say, “It’s safe to say that in at most two weeks the entire globe would have cooled to hundreds of degrees below zero.” What is it about two weeks that makes it safe to say that that’s how long it would take? And how many hundreds below zero? And zero in what scale? Because in degrees Celsius, you’re limited to about 273 degrees below zero. Fahrenheit, 459. In terms of Kelvins and degrees Rankine, they both use zero for absolute zero.

    Oh, and nuclear power doesn’t last “forever.” Sure, it lasts a long time, but it’s extremely inexact to say it lasts “forever.”

    Raj

    July 25, 2008 at 8:50 am

  6. if the sun disappeared..??? i can imagine it. no body cant live without it. if the sun disappeared it’s mean the end of the world.

    beranibaca

    July 25, 2008 at 6:22 pm

    • has any heard of god???????

      william mccall

      August 4, 2013 at 1:53 am

  7. Raj, you seem to be missing the spirit of the post. Doug clearly intended the post to convey to the general public a rough idea of the condition of earth without the sun. In terms of the human lifespan, nuclear power will seem to last “forever”. In terms of human perception, hundreds of degrees below zero is going to be god damned cold (never mind fatal) regardless of which scale.

    I guess what I’m really trying to say is, “Loosen up.”

    Andrew

    August 2, 2008 at 11:00 am

  8. Thanks Andrew. I actually decided when writing the post to go with “hundreds of degrees below zero” instead of 30-50 degrees Kelvin (The surface temperature on the outer planets) because it would convey meaning to most readers, whereas 30-50 degrees Kelvin might as well be Greek for many people, even if it would have been more accurate scientifically. And I did state my reasoning why I think the temperature would drop so precipitously in the Sun’s absence. If someone can point out a flaw, or some reasonable mechanism that would allow the Earth to retain livable surface heat without the Sun, I’ll stand corrected.

    unitedcats

    August 2, 2008 at 4:37 pm

  9. I’m thinking that there’s enough heat conveyed thru the crust by conduction that the “air snow” might not “stick” much like when it snows but the ground isn’t cold enough to keep it frozen.

    And natural hot spots, hot springs, volcanoes, etc. would also heat the frozen air much like in “A Pail of Air” so that some humans might be able to survive at least until they ran out of ways to keep themselves fed.

    Just a thought.

    Jeff

    February 6, 2009 at 6:51 am

  10. What was not addressed was the physical impact on earth’s motion as a result of the sun disappearing. I would like to hear some educated analysis of this.

    What would happen to the earth’s rotation and orbit and would the moon continue to orbit the earth?

    If I am correct, applying Newton’s first law of motion the earth would stop its orbit as there is no Sun to orbit and it would start moving in a straight line forever (or until acted upon by some other force). If it is true its orbital velocity would stay the same (approximately 30 km per second or 108,000 km per hour) then after a year the earth would have moved about 1 billion km in a straight direction from its position when the Sun disappeared. The earth would continue to wander across our local region unless it was captured by a large planet or another star.

    Given the earth would be moving through the blackness of space, soon the surface of the earth would be surrounded by temperatures at the level of the cosmic microwave background radiation i.e. 2.7K. As was pointed out, the internal temperature of the earth would be warmer and it is conceivable that microbes and other organisms could continue to live at the bottom of the ocean where magma vents exist and perhaps even nearer the surface at places like Yellowstone National Park or Iceland.

    As for the earth’s rotation and its relationship with the moon, I will have to leave that to others with a better physics background than I have.

    Just some thoughts.

    Cal

    August 24, 2009 at 1:59 pm

  11. Well, yes, the Earth would travel in a straight line from where it was when the Sun vanished, possibly slightly influenced by Jupiter and such as they headed their own directions. And the Moon would continue to orbit the Earth. The Earth’s rotation would continue. I’m pretty sure the one thing that would change though is the Earth’s axis of rotation, the Sun is a stabilizing factor in that, so it would tend to “wobble” so to speak. That wouldn’t really change anything, just the Moon’s path through he sky would slowly change.

    The Moon of course wouldn’t have phases, but would still be visible by starlight.

    Eventually the Earth would cool down to 2.7 K, but that would take billions of years. Pluto and the other trans-Neptunian objects have surface temps around 40k and they get essentially zero energy from the Sun. Earth, heated by radioactive decay and tidal forces from the Moon, should stay somewhat warmer for a long long time.

    And yes, I could easily be over ruled by someone with expert knowledge of orbital mechanics.

    unitedcats

    August 24, 2009 at 8:06 pm

  12. Actually, the moon is the main (and, I believe, rather small) influence on the Earth maintaining its 23.5 degree tilt angle, as well as the length of day. I say small influence, and the Sun’s even smaller influence, because I would think that after all these several billion years the tilt might have been corrected by now. So, now that I think about it, I believe the moon and sun have no effect whatsoever on the tilt! Correct me if I’m wrong! LOL

    Bill Frain

    December 9, 2009 at 8:54 am

  13. I read in a magazine that if the sun disappeared the average temperature of th earth after a week would be -17 degrees Celsius. If this is true the richer, cooler headed minority would have time to sell off there homes at a very low price along with most things in it, flee to Iceland (where about 80% of all homes already use geothermal power), buy a very small home and use the extra money to buy an indoor farm to feed themselves. They could then start any renovations needed to insulate there plants and themselves from the cold.

    Scott

    December 23, 2009 at 3:44 pm

    • Unfortunately, within a few months the temperature would be around -170. Plus, plants need light and heat. I don’t think we’d have enough of either in those conditions.

      Bill Frain

      January 8, 2010 at 2:50 pm

      • Plus there’s the small matter of needing an atmosphere. Carbon Dioxide freezes at -78 deg. C so once the Earth’s temperature falls below that the CO2 will start to freeze out. No CO2 in the atmosphere means no photosynthesis. Then, once the temperature falls below –182 deg. C the Oxygen will start to freeze out. At -196 deg. C the Nitrogen begins to freeze. So by the time the temperature of the Earth is below about -200 C, there would be essentially no atmosphere left – it would all be lying on the ground in the form of various types of snow.

        GregS

        February 9, 2012 at 9:14 am

  14. The rate of cooling would not be linear.
    The Earth could only lose heat by radiating it, and the rate of loss is proportional to the fourth power of the temperature (assuming black body characteristics). So it would lose heat fast, and then the rate of heat loss would slow dramatically.

    dirk bruere

    January 26, 2010 at 5:15 pm

  15. What a cool + revealing article. I saw a vid on youtube and it reminded me of your page:

    joseph young

    April 23, 2010 at 12:01 pm

  16. I think you missed the point of the question entirely. It’s a question about relativity and space-time as defined by Einstein. The real question is when the two critical events would take place relative to each other. (1) the loss of light, and (2) the loss of the gravitational pull. It’s a great question because you can’t answer without understanding relativity. Or better yet, the answer is the best illustration I know of to explain relativity/space-time. Here is the site with that answer. http://earthsky.org/space/sun-light-motion-change

    Peter

    October 17, 2010 at 5:32 pm

  17. (1) the loss of light would occur 8 minutes after the sun vanished and (2) there would be no loss of gravitational pull. According to Einstein, there is no gravitational pull. The planets orbit the sun because the suns large mass causes a distortion in space-time. If the sun disappeared, the distortion would no longer be there and the earth would travel in a straight- ish line…. again you have to understand Einstein’s general relativity principle to understand what happens…

    Zoei

    March 7, 2011 at 5:44 pm

    • Actually Einstein’s General Relativity would state that if the Sun mysteriously disappeared the curvature of space time would not resort to being flat instantaneously, but the gravity waves would ripple at the speed of light. So it would be safe to assume the Earth would not go off in a straight line immediately but around the same time that the light no longer was falling on the Earth some 8.3 minutes later.

      Jonathan Miller

      July 28, 2011 at 4:58 pm

  18. Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet’s core would equal the heat that the Earth radiates into space.

    Daniel

    March 8, 2011 at 7:08 pm

    • You should put quotes around that since you didn’t write it and all. I am sure you did not mean to plagiarize :)

      Victoria

      March 14, 2012 at 6:15 pm

  19. Yes it’s true that if the Sun disappeared, it would take around 8 minute before it all went dark, but what about gravity, I know it’s said that nothing goes faster than light, but what stops gravity from having an instant affect?
    How can you prove that gravity is not instant?

    Henning

    May 25, 2011 at 10:34 am

    • Einstein’s theories say that gravity’s affects propagate at light speed. As far as I know, Einstein’s theories have been validated seven ways from Sunday. I know that people far smarter than me don’t have a problem with this. Do you have a viable theory contravening Einstein? The burden of proof is on you.
      —Doug

      unitedcats

      May 25, 2011 at 11:41 pm

  20. Reply to unitedcats!
    As Scientist haven’t yet been able to catch a gravity wave, could this be because they do not exist and if they do not exist, it could be because gravity is instant. My scientific knowlidge is very limited, I was just curious and wanted to know, how and by what means they have been able to work out the speed of gravity, as there has never been a sun or star there instantly disapeared?…

    henning

    May 26, 2011 at 6:03 am

    • Relativity and gravity is not one of my interests. I found this which explains it, at least I think it does:

      http://www.desy.de/user/projects/Physics/Relativity/GR/grav_speed.html

      I know some attempts to measure gravity on a very small scale are in the works, partly to answer the question of gravity’s speed, an partly because it may give clues about what is “outside” the Universe. I haven’t really looked into it recently though. —Doug

      unitedcats

      May 26, 2011 at 10:43 am

  21. Thank you unitedcats!
    That was exately what I was looking for

    Henning

    June 4, 2011 at 7:06 am

  22. How long would people be able to live if they managed to live on the bottom of the ocean, in a base or something?

    Krysta

    June 22, 2011 at 6:47 pm

    • If the Earth were heading in the direction of the nearest star how long would it take to get there, or at least start to be warmed by it?

      Krysta

      June 22, 2011 at 6:59 pm

  23. Doesn’t the starlight come from the suns light bouncing off planets? If so then how would we have such vivid starlight?

    James

    February 24, 2012 at 1:36 pm

  24. I had just had a dream about the Sun being consumed and found this article which is very informative. It was terrifying to watch the Sun blip out of existence and I had immediately started taking precautions like sealing the place I was in to keep the heat inside. If Earth were to wander through space we would most likely be impacted by something or other causing total destruction. If we don’t run into the other planets we would be hit by something else because Jupiter’s gravity protects us from impacts at this point. Without Jupiter we would be defenseless against all the things flying around in our solar system. It could also be possible that we would orbit around Jupiter at some point if Earth heads in that direction. We would become a moon of some kind! Mercury is going to run into the Earth before the Sun consumes us so I think we should be keeping our eye on that little devil :P

    Victoria

    March 14, 2012 at 6:23 pm

  25. If the sun disappears, and no other star is close to earth, the entire solar system, including earth, would freeze to a temperature close to absolute zero. Absolute zero is the lowest possible temperature anything could have, it is so cold that even sound ceases to travel. It is some –273.15°C or –459.67°F. Although earth cannot reach this temperature because it would stop existing (If it reaches absolute zero, it does not have a kinetic energy, which is impossible) but it can still reach a very close temperature to it, perhaps −260°C. The cause of this extreme coldness is the absence of heat. Our only effective heat in our zone is the sun, so if it disappears, nothing will be heating earth, making it extremely cold. Oceans, and all the living creatures would instantly freeze, and the atmosphere would literally “fall down”: Temperatures close to absolute zero are lower than any solidification temperature, thus causing the molecules of the air to freeze, become solid, and fall to the ground.

    SamAz

    May 25, 2012 at 7:39 am

    • On the contrary, radioactive decay in the Earth’s crust will provide heat for billions of years, think volcanoes, hot springs, etc. And since the Moon would still orbit the Earth, tidal forces would also create heat. Again, for billions of years. The Earth would get cold, especially the surface, but it will be a long long time before it cools to absolute zero.

      unitedcats

      May 25, 2012 at 9:22 am

    • Hi- Fascinated by hypothetical Sun loss and the idea of different snows dropping out individually from the atmosphere with temperature fall. But we’ve been arguing here about methane snow being orange. (I know- too much time on our hands….). Aren’t Uranus and Neptune blue/green because of frozen methane, Pluto brown only because of dirty frozen methane, yet doesn’t UV light turn methane to brown?

      R

      December 30, 2012 at 11:20 am


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