Volcanoes/Meteorites Blacking Out Sky

[Centerfield97]

Would it be possible for ash from a volcano or crashing meteorite to black out the sun for an extended period of time? How long?

Also, would it be possible to, per say, have the sky over Asia be blacked out, but have Europe be mostly/partially clear?

 

[Sheilawisz]

Hello Centerfield!! Some volcanic explosions have been exceptional, and powerful enough to cause the effect that you are describing: The blast of Mount Tambora in 1815 turned days into a completely dark night even 600 kilometers away from the explosion, and other historical large eruptions like Krakatoa and Santorini have caused similar effects.

Yes, it's possible that the sky would be covered in Asia and partially clear in Europe...

A large asteroid could plunge the entire planet into a freezing night (that is, when the fire storms from the blast are over!!) this sounds like a good setting for a Fantasy story, by the way =)

 

[Saigonnus]

Scientists estimated that the meteorite that killed the dinosaurs was six miles wide and was sufficient to turn the world black for decades. Basically most life on earth was eliminated and only the most hearty forms of life survived and in isolated pockets near the equator. It is entirely possible to have only a relatively small area affected, though generally those things have to do with geography and weather. Santorini exploded in the times of ancient egypt and since it was an island, the ash cloud was a widespread thing, likely into europe and asia. Debris (pumice rocks mostly) washed up on beaches all over egypt, and the country supposedly went dark for 3 days from the ash cloud spreading through the atmosphere.

Other volcanic eruptions have been fairly localized (ones that don't throw alot of ash for example) and the pyroclastic flows may only extend out a few hundred kilometers from the volcano.

Generally whether it's an impact or a volcanic eruption, the environmental conditions are similar. The temperature drops under the affected area, acidic rain falls from all the stuff thrown into the air, affecting crops and livestock. It basically simulates a nuclear winter for all intents and purposes without the radiation. In colder northern regions (i.e siberia) or areas with sufficient elevation it could get so cold as to make the environment basically inhospitable to most life forms.

 

[Centerfield97]

Wow, thank you guys!

My main reason for asking this is that I have this continent where most of the action is centralized in the West, with the contents of the East being fairly unknown. However, the civilization living in the East is very religious concerning the sun, so I was curious what sort of asteroid/volcanic activity might block out the sun for, oh, say a few months/maybe even a year. Enough to make them think that their God had abandoned them and that they must move West in search of new lands, which are for the most part unharmed by the event.

Does this sound plausible? What effects might the East suffer from such an impact/eruption?

 

[Saigonnus]

To be blocked out for months, it would likely take a fairly substancial single event; one that would likely cover the west also with it's area of effect or perhaps consider a series of 2 or 3 smaller events that add up to a lengthened period of time. Santorini's volcano Thera erupted in ancient times (1600s bc if I remember correctly), and while it was one of the largest eruptions in the ancient world, it blocked out the sky for only a few days. Couple an event along that lines with a large meteor strike (like a half mile mile across) maybe toward the end of that few day period) and you'd have a lengthened time for a black out, but more than a month I would say is unlikely without it affecting the west also.

However, you could easily have the people residing in the east use these event like a portent and many of the classic asian cultures were very superstitious when it came to their spiritual/religious beliefs. It wouldn't take more than a few days for a particularly fervent culture to become convinced their god is unhappy with them. Maybe the first event is seen as a "warning" where the sky goes dark for a week and the people see it as such. The second event could happen and there is a mass exodus from the area and into the west.

Also consider other options as well, perhaps there is migration for more mundane reasons. Perhaps there was an extended period of drought (likely they'd also consider this punishment from their god i.e. the sun is too strong) and the food supplies and water are beginning to run low. Sandstorms could be more common as the water evaporates (they tend to block the sky too) and tend to wreck havoc in everyday life. People tend to go where there is likelihood to survive, and if the west is the only place they can go, that is where they'd go. Series of events such as this are far more common in a geologic sense as the planet warms and cools as time goes by.

 

[Shockley]

A good thing to start researching might be this: Consequences of the April 2010 Eyjafjallajökull eruption - Wikipedia, the free encyclopedia

It didn't quite block out the sun, but everything looked like this for a while:

 

[SeverinR]

Question:
If a meteor was blocking out the sun, would the temperature drop as the suns rays are blocked from even the upper atmosphere? Clouds can bring cool temps, but what would the space shadow affect be?
Sudden cold front, or would the area adjust slowly? (Best and worst case?)
What would the time frame be from noticed shadow until impact? (rough estimates, assuming the meteor wasn't a world destroyer.)

Wasn't the eruption of the volcano in the US like a blizzard or fog of ash?

 

[Benjamin Clayborne]

Question:
If a meteor was blocking out the sun, would the temperature drop as the suns rays are blocked from even the upper atmosphere? Clouds can bring cool temps, but what would the space shadow affect be?
Sudden cold front, or would the area adjust slowly? (Best and worst case?)
What would the time frame be from noticed shadow until impact? (rough estimates, assuming the meteor wasn't a world destroyer.)

I'm assuming you're talking about a meteor in space blocking out the sun.

There's pretty much no way this could realistically happen, for a variety of reasons. In order for the meteor to cause the kind of effect you're describing, it would either have to be very close to the planet, or it would have to be the SIZE of a planet. However, either case is moot, because...

...no object will sit stationary between a planet and the star it orbits, except at one point: L[SUB]1[/SUB], the first Lagrangian point. It depends on the masses of the objects, but in the Earth-Sun system this point is about 1% of the way from the planet to the star. In Earth's case, that's 1.5 million km, which is about four times greater than the Earth-Moon distance. Correspondingly, with the help of a little trigonometry, we can find that in order for an object between Earth-Sun to occlude the sun at a distance of 1.5 million km, the object would have to be about 14,000 km in diameter, which is about 10% larger than the Earth.

And then it'd be another planet, and there's really no way two such objects could coexist at such a short distance for a long period. They'd interfere with each other's orbits, drift out of the Lagrangian points, or possibly collide. Even if the object had just gotten between the Earth and Sun, how did it get there? Why did it stop exactly between the two?

If the meteor was in fact much smaller and much closer, then you'd have to explain how it stays stationary between the Earth and the Sun. Absent some kind of station-keeping mechanism, like internal rockets--or, I guess, magic--the meteor would either fall into Earth's gravity well (either orbiting or crashing into the Earth, or causing huge tidal problems), or drift out of Earth's orbit altogether.

All this assumes, of course, that you're using a planet and star with similar physical and orbital characteristics to the Earth and the Sun. If you don't, you might have a whole other set of problems.

 

[Devor]

...no object will sit stationary between a planet and the star it orbits, except at one point: L[SUB]1[/SUB], the first Lagrangian point. It depends on the masses of the objects, but in the Earth-Sun system this point is about 1% of the way from the planet to the star. In Earth's case, that's 1.5 million km, which is about four times greater than the Earth-Moon distance.

That's really cool, I've never heard that. If an object was caught in that spot, wouldn't it look like the sun had a black hole in the middle? There's a lot you could do with that concept.

 

[Benjamin Clayborne]

That's really cool, I've never heard that. If an object was caught in that spot, wouldn't it look like the sun had a black hole in the middle? There's a lot you could do with that concept.

The sun is so bright that no object small enough to maintain station in L[sub]1[/sub] would be visible against it—it would be totally washed out. You'd need special equipment (telescopes with lots of special filters) to even be able to make it out at all. Anything big enough to perceive as a "hole" would be too big to be in a stable orbit. (Plus, you'd have to stare at the sun to see it, which, no.)

If the local star is somehow dim enough to look at safely, then you could totally do something like this. Also, if the story is fantasy (and so nobody understands astronomy), you can just have the sun turn dark as if something is blocking it. People can tell if the sun is blocked without having to stare directly at it.

 

[SeverinR]

I was talking about a meteor on collision course, so the distance would be to close to feel the effects of the shadow before impact or it would be a planet killer.

Alteration of gravity or orbits bring severe weather problems don't they? Earthquakes, massive storms, etc.

 

[Ravana]

The sun is so bright that no object small enough to maintain station in L1 would be visible against it—it would be totally washed out.

Unless it was really, really low density, and thus large enough to cast a significant shadow.

Capture of such an object is all but out of the question: it would have to be placed there on purpose. Conceivably, a rogue planetary mass might move into the system slowly enough that it could be pulled into a stable orbit; even then, I highly doubt that its orbit would ever come to precisely match the Earth's in such a way that it would always be seen as occluding the sun. It might well transit (think "eclipse") the sun regularly, but the events would be, well, transitory. Keep in mind that it would also have to possess the same orbital plane as the Earth; even minute differences would mean that, most times around, transits would not occur (which is why astronomy wonks get excited whenever Mercury or Venus transits happen).

•

Nothing could "black out" the sky for any length of time that wouldn't destroy the planet itself, I'm fairly certain. It would require too much debris—and since the debris would be heavier than air, most of it wouldn't stay in the atmosphere for long. Darkening the sky for months, even a year or more, is another story, and, yes, as Sheilawisz mentions, this is well attested, but this will be from the effects of fine particulate matter suspended high in the atmosphere; the "turning day into night" effect will only apply to a very limited geographical area for a very short period of time. ("Very" taken in terms of the entire planet, of course.) In addition to those limits, it also matters where the event takes place: the effects may be largely limited to only one hemisphere, as weather patterns tend not to transfer them across to the other. (The Tambora and Krakatoa volcanoes are both in the Southern Hemisphere, but only barely; presumably, roughly as much material went each direction.)

The K-T event—the one that hypothetically caused the extinction of the last wave of dinosaurs: opinions are still divided on that—was far more massive than any volcanic eruption ever attested (an estimated 125,000 times the force of the Tambora eruption, the largest in recorded history), and so constitutes an exception to the distribution of effect. Even it, assuming estimates are roughly correct, only blocked out 10% or so of the sun's light for perhaps a decade… more than enough time to cause catastrophic changes to life, but hardly "blacking out" anything, except in the short term. And in fact, it isn't the dust that caused this medium-term dimming, in the proposed scenario: it was the release of massive amounts of sulfur dioxide (in gas/aerosol form) that did it. Which means there may have been very little visible effect on the sun at all, from the point of view of ground observers, once the heavier particulate matter settled.

 

[SeverinR]

Unless it was really, really low density, and thus large enough to cast a significant shadow.

Capture of such an object is all but out of the question: it would have to be placed there on purpose. Conceivably, a rogue planetary mass might move into the system slowly enough that it could be pulled into a stable orbit; even then, I highly doubt that its orbit would ever come to precisely match the Earth's in such a way that it would always be seen as occluding the sun. It might well transit (think "eclipse") the sun regularly, but the events would be, well, transitory. Keep in mind that it would also have to possess the same orbital plane as the Earth; even minute differences would mean that, most times around, transits would not occur (which is why astronomy wonks get excited whenever Mercury or Venus transits happen).

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Nothing could "black out" the sky for any length of time that wouldn't destroy the planet itself, I'm fairly certain. It would require too much debris–and since the debris would be heavier than air, most of it wouldn't stay in the atmosphere for long. Darkening the sky for months, even a year or more, is another story, and, yes, as Sheilawisz mentions, this is well attested, but this will be from the effects of fine particulate matter suspended high in the atmosphere; the "turning day into night" effect will only apply to a very limited geographical area for a very short period of time. ("Very" taken in terms of the entire planet, of course.) In addition to those limits, it also matters where the event takes place: the effects may be largely limited to only one hemisphere, as weather patterns tend not to transfer them across to the other. (The Tambora and Krakatoa volcanoes are both in the Southern Hemisphere, but only barely; presumably, roughly as much material went each direction.)

The K-T event–the one that hypothetically caused the extinction of the last wave of dinosaurs: opinions are still divided on that–was far more massive than any volcanic eruption ever attested (an estimated 125,000 times the force of the Tambora eruption, the largest in recorded history), and so constitutes an exception to the distribution of effect. Even it, assuming estimates are roughly correct, only blocked out 10% or so of the sun's light for perhaps a decade… more than enough time to cause catastrophic changes to life, but hardly "blacking out" anything, except in the short term. And in fact, it isn't the dust that caused this medium-term dimming, in the proposed scenario: it was the release of massive amounts of sulfur dioxide (in gas/aerosol form) that did it. Which means there may have been very little visible effect on the sun at all, from the point of view of ground observers, once the heavier particulate matter settled.

If there was sulfur dioxide, wouldn't there be acid rain? Not sure of ecological damage of acid rain to plants and living creatures. Probably didn't smell very good in those areas, if you could breathe.

 

[Ravana]

Yep, the sulfur dioxide combined in the atmosphere to produce acid rains–which can be anything from inconvenient to devastating for aquatic life, soil and vegetation. In most cases, the effect is to disadvantage certain organisms and create new or broader niches for certain others… depending on which ones, this can potentially disrupt entire food chains.

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By the by, for anyone who wants to see a fictionalized account of this kind of cataclysm, I worked one up for the Mythic Archipelago project. Some people had decided they wanted a focal event for the Archipelago's calendars to date from; others had suggested that it might be neat if the planet had more than one moon. The discussion leading up to the story can be found here:

http://mythicscribes.com/forums/mythic-archipelago/899-calendar-causing-event.html

I combined the two ideas… and created a tale of something stealing a moon. While the events might be a bit improbable–the positions of the bodies involved have to be pretty precise for it to happen the way I have it–as far as I can tell they are at least possible. This thread:

http://mythicscribes.com/forums/mythic-archipelago/979-tale-two-two-moons.html

contains both the perspective of ground witnesses (leaving the details flexible enough that other writers could choose which effects were experienced at varying geographical locations) and the actual astronomical events that were being interpreted through their limited knowledge (and occasionally their misunderstandings). It isn't necessary to read the first thread to appreciate the second one, but it is sometimes nice to see the thought processes behind a piece of writing… and it helps explain a couple of things that got worked in as "in-jokes."

 

[Sheilawisz]

Another interesting possibility for this volcanic catastrophe scenario in a Fantasy story would be "The Year without a Summer" like it happened in our world in 1816: After Mount Tambora was blown to the heavens in the worst volcanic blast recorded by history, the global weather patterns were affected and 1816 became known in North America and Europe as the year without a summer.

Frost and snow devastated the fields when it was supposed to be summer, causing crop failures and famine... it was really terrible, and I have no idea what would happen with our civilization if a blast similar to Tambora (or even several of them within the same year) took place in our times.

People in 1816 had no idea what had caused this, so a similar event could add a touch of mystery to a Fantasy world =)

 

[Jess A]

Check out the film 'Supervolcano'. It is, of course, speculation based on prior historical events, but it describes the effects of a 'supervolcanic eruption'. It focuses on the caldera of Yellowstone National Park and what may happen when it eventually erupts. It shows that if the magma chamber beneath the ground was found to be a certain size and viscosity, it would eject such an extreme amount of dust and ash and rock into the air through one gigantic eruption (or several smaller ones) that 3/4 of the USA would be covered in ash - and the effects would be felt across the planet.

Note that any eruption large enough to block out the sun will have other noticeable effects on the planet. Also watch for bodies of water - tsunamis can occur in oceans and lakes through certain types of seismic activity. You need to find out whether those in the West would be affected (even if far more subtly).

I personally love volcanoes and find the subject fun to write about.

Alternatively, you could have an eclipse and even if it is only momentary, they could see it as a bad omen and leave. Lunar eclipses are likewise interesting - I have watched them and the moon goes blood red. Always great for omens and prophesies and the like.

 

[Sheilawisz]

@Little Storm Cloud: I also love volcanoes, they are so fascinating!! I laugh when sometimes they say in documentaries or books that hurricanes, earthquakes, tornadoes or lightning are the greatest powers of nature, because I know that volcanoes are really the most fearsome power of nature in this planet =)

Maybe a supervolcano would be a little too extreme for a Fantasy story, but it would be interesting anyway... Something like the Siberian Traps would be more epic!!

 

[gavintonks]

Krakatoa darkened the world for 3 and a half days as the dust cloud traveled around, however I saw the meteorite a couple of years ago there is a clip on you tube over Johannesburg, the energy turned night into day and there was no debris, also they are usually molten se the crater in Russia that leveled a Forrest for 30k, so I would say meteroite unlikely

 

[Sheilawisz]

Gavintonks, I think that you mean the mysterious and still unexplained Tunguska Event in Siberia... that is very fascinating as well!! Some thories say that it was a comet that exploded very high above the forest, while others say that it was a crippled starship that deliberately chose to explode above such an isolated and unpopulated region =)

All that we know about the Tunguska Event is that something came from the sky that day and exploded with unbelievable power... What was it? Maybe we will never know for real.

 

[J.P. Reedman]

Volcanic eruption can cause devastation for years,and far from the source. The sun might not be 'blocked out' for more than a few days but the resulting climate change could cause severe problems. After Santorini erupted c1600 BC all the bronze age cultures of the Med gradually collapsed and the effects were felt as far away as northern Europe, as evidenced by tree rings, which show a disruption in growth at this time. In around 1100 BC Hekla erupted in Iceland, and this was thought to have significant effects on the British Isles--the climate became wetter and cloudier and farmland turned to moorland and had to be abandoned. Between these two dates you see the wane in the bronze age culture of the area, and by 1000 BC monuments such as Stonehenge were out of use, possibly because there was less chance of viewing the solstices. At the same time swords become longer, more weaponry appears and people settle on defended hilltops.