Survivable geological events that can enable sudden viewing of a planet

[Ultimate Steve]

Title gore for sure, but this is a bit complex...

I recently had the idea to write a story about a system of binary planets, both with intelligent life at similar stages of progression with different strengths. In one sudden event the civilizations would be made aware of each other and they'd attempt to explore space in some way, etc...

What I'm currently struggling with is how to make the sudden reveal seem realistic. The best idea I have right now is to make one of the planets extremely cloudy, so very little light makes it ot the surface, so not even the star will be distinguishable most of the time. But then the clouds would have to somehow disappear without altering the atmospheric composition. And the life on the planet would have to adapt to much more solar heating and a bunch of other things.

I have one idea to eliminate the need for a reveal entirely but I'm not sure I want to go for it... Any ideas on if or how this would be possible?

[magnemoe]

You can see an modern city well from orbit but can you see it from L1? Could you see London 200 years ago from orbit? not during the light with the eyes as I imagine. 

[DerekL1963]

Depends on the distance between them...  We really need to know that to examine potential scenarios.

[p1t1o]

Tidally lock the planets, put habitable land only on the far side of one of them.

Even with shipping possibly travelling the far side, it would be a long time before another civilisation could be confirmed by either party.

Sudden reveal: space travel, or more likely now that I think about it, radio communications (did that come bout around the same time as the electric light?)

 

 

Edited November 12, 2018 by p1t1o

[magnemoe]

The major issue is how they became technological civilizations at the same time, our is an mix of unlikely factors.You could probably got it back in antiquity but it would require an perfect storm. 
And yes an industrialized version of the roman empire could well been very dystropian, an industrialized slave society, we fought an the most deadly war ever against one of them. 
Or we might got an early start and fighting global warming 12K years ago, herding and then farming stated early because an lady tamed horses and dogs 35K years ago
Or Japan is slowly colonizing the world today because Europe failed. 

SM. Stirling In the Courts of the Crimson Kings had an interesting take on it. You could not take on the empire of China in an way you had anything to take over, not as you could send an army group even if you had it and you would not as they had some scary capabilities who could be worth an planet by itself. 

[FleshJeb]

Rocheworld and Return to Rocheworld

Basically, what @p1t1o said.

Edited November 12, 2018 by FleshJeb

[Ultimate Steve]

27 minutes ago, magnemoe said:

1. You can see an modern city well from orbit but can you see it from L1? Could you see London 200 years ago from orbit? not during the light with the eyes as I imagine. 

 

23 minutes ago, DerekL1963 said:

2. Depends on the distance between them...  We really need to know that to examine potential scenarios.

 

21 minutes ago, p1t1o said:

3. Tidally lock the planets, put habitable land only on the far side of one of them.

4 .Even with shipping possibly travelling the far side, it would be a long time before another civilisation could be confirmed by either party.

5. Sudden reveal: space travel, or more likely now that I think about it, radio communications (did that come bout around the same time as the electric light?)

 

4 minutes ago, magnemoe said:

6. The major issue is how they became technological civilizations at the same time, our is an mix of unlikely factors.You could probably got it back in antiquity but it would require an perfect storm. 
And yes an industrialized version of the roman empire could well been very dystropian, an industrialized slave society, we fought an the most deadly war ever against one of them. 
Or we might got an early start and fighting global warming 12K years ago, herding and then farming stated early because an lady tamed horses and dogs 35K years ago
Or Japan is slowly colonizing the world today because Europe failed. 

SM. Stirling In the Courts of the Crimson Kings had an interesting take on it. You could not take on the empire of China in an way you had anything to take over, not as you could send an army group even if you had it and you would not as they had some scary capabilities who could be worth an planet by itself. 

Thank you all for these responses.

1. I'm guessing that you could probably see those cities with telescopes and stuff.

1 and 2. I was planning on making the two planets pretty close to each other, closer than the Earth and Moon are to each other to make travel between the two reasonably simple, if anything in space can be considered simple...

3. I had considered this, but even with shipping:

4. You could get telescopes on the boats, which, even if you had to spot the other planet's boats, would still be technically possible... This is probably the best idea yet, actually, if we ignore the odds of there only being habitable land on those exact halves of planets.

5. This is one of my biggest problems so far. While it would be a great way of first contact, I'm aiming for another feel. Unfortunately it's likely they would discover each other by radio if sudden visual wasn't an option.

6. They are going to be strong in different areas, and probably at least a decade off of each other in the important areas. For example, if one planet has a thicker atmosphere and/or lower gravity they will probably be better at atmospheric flight than the other world. If one world has harsher weather, they will likely be better at building things. But as far as both species being at approximately the same level of progression, even though it's improbably, I'll handwave it and call it "it had to happen somewhere."

6 minutes ago, FleshJeb said:

Rocheworld and Return to Rocheworld

Basically, what @p1t1o said.

Ahh, I forgot, it's 2018, all the good ideas are already taken... Although my idea is different enough than this that I think it will work.

Thank you all for your responses!

[Racescort666]

What about one of them being highly advanced in the past and something like nuclear war drove everyone into bunkers for generations? Meanwhile, the other planet advances sufficiently to realize something close to space travel with neither side knowing that there is an advanced society just out of sight. Planet A suffers nuclear war, they declare the planet inhabitable for XXX years (insert time not roman numerals for 30) and everyone retreats to self-sustaining bunkers. After Planet A has a nuclear war and goes underground, Planet B figures out telescopes and stuff/decides to start to think critically about the rest of the universe. While Planet B is developing technology, Planet A is reclaimed by wildlife. Planet B is to the cusp of developing space travel (I assume this is where your story starts). [Insert plot device] Planet A and Planet B discover they are people. Planet A maybe or maybe doesn't remember how to build spaceships. You could put the people on Planet A in the bunkers for an arbitrarily long time and they forget technology.

Kinda campy I think but I suppose there isn't anything "technically wrong" with it.

[Steel]

13 minutes ago, Ultimate Steve said:

Title gore for sure, but this is a bit complex...

I recently had the idea to write a story about a system of binary planets, both with intelligent life at similar stages of progression with different strengths. In one sudden event the civilizations would be made aware of each other and they'd attempt to explore space in some way, etc...

What I'm currently struggling with is how to make the sudden reveal seem realistic. The best idea I have right now is to make one of the planets extremely cloudy, so very little light makes it ot the surface, so not even the star will be distinguishable most of the time. But then the clouds would have to somehow disappear without altering the atmospheric composition. And the life on the planet would have to adapt to much more solar heating and a bunch of other things.

I have one idea to eliminate the need for a reveal entirely but I'm not sure I want to go for it... Any ideas on if or how this would be possible?

My idea would be to make one of them an underground civilisation that rarely went above ground. Don't know whether that works in with whatever story you have so far, but that's my two cents.

[Scotius]

Well, it would be simpler if inhabitants of one (or both) planet actively tried to communicate with the other planet. Even before development of radio communication, late XIX century scientists dreamed up plans of contacting highly developed, canal-building civilisation on Mars Plans included draving enormous geometrical figures on the surface of Sahara, or felling millions of trees in Siberia  in hopes that Martian telescopes would be sufficiently advanced to pick up images of human activities clear enough. Early Polish sci-fi writer Władysław Umiński wrote a charming novel about such low-tech communication attempt. It involved lighting up nine extremely bright signal lights on the "cross" plane in South America during the Great Opposition of Mars. Protagonists of the book barely survived the adventure (locals were not too happy with crazy foreigners turning their peaceful night into an EXTREMELY bright day without any warning) but the attempt was ultimately successful, as couple of months later astronomers photographed bright spots on Mars' nightside forming another cross.

You can use something similiar - we can't be only sentient beings in the Universe obsessed with finding neighbours we could chat with

[DerekL1963]

46 minutes ago, Ultimate Steve said:

I was planning on making the two planets pretty close to each other, closer than the Earth and Moon are to each other

Not if you intend to be in any way realistic.
 

48 minutes ago, Ultimate Steve said:

Unfortunately it's likely they would discover each other by radio if sudden visual wasn't an option.

Why unfortunately?  If you're trying to stop them from talking to each other, whatever does that will also restrict them basically to early/mid 1800's tech - forever.  (Basically, no radio means no space flight.)

[Ultimate Steve]

5 minutes ago, DerekL1963 said:

Not if you intend to be in any way realistic.
 

Why unfortunately?  If you're trying to stop them from talking to each other, whatever does that will also restrict them basically to early/mid 1800's tech - forever.  (Basically, no radio means no space flight.)

1. Pardon any ignorance I may have, but why not? Is there a technical reason why a binary system couldn't exist that close? I did look up roche limits and stuff, please correct me if I'm wrong, but it seems like they could work out. If I read the article right, the moon could exist ~20 times closer to Earth and still be able to exist, although tidal interactions and the moon getting there in the first place would be big problems.

2. I'm not against using radio to communicate, especially later on, but I'd like the initial discovery moment to be a bit different. I've done some more thinking and I think I know how I want it to go, but I'd rather not say it here in case I do end up writing the story...

[Ultimate Steve]

You know, this would also make an interesting KSP planet pack... Starting on a habitable world binary with another habitable world.

[DerekL1963]

21 minutes ago, Ultimate Steve said:

Pardon any ignorance I may have, but why not? Is there a technical reason why a binary system couldn't exist that close? I did look up roche limits and stuff, please correct me if I'm wrong, but it seems like they could work out. If I read the article right, the moon could exist ~20 times closer to Earth and still be able to exist, although tidal interactions and the moon getting there in the first place would be big problems.

The Roche limit is the limit at which existing bodies aren't pulled apart by tidal forces.  It's the question of whether they can form in the first place.  (As well as how geologically stable they'd be.)
 

23 minutes ago, Ultimate Steve said:

I'm not against using radio to communicate, especially later on, but I'd like the initial discovery moment to be a bit different.

Without some heavy duty deus ex machina it's going to be hard to develop a reasonable solution to hiding one civilization from the other once telescopes and radio start being invented.  Curiosity about that thing in the sky is going to run high.

[XB-70A]

The hided population actually was far more advanced. Having been responsible for many wars they decided to become peaceful and to live in harmony. To ensure that they do not repeat their same mistakes, they prefer not to interfere with the primitive population of the neighboring planet... Then, against all odds they became the victims of a catastrophe of planetary magnitude, when a massive body came to impact with it. Not only did the impact destroy a part of the planet, and lifted so much ash and debris that it covered the entire surface, but it was so violent that it projected a part of it into another dimension, opening the way for vicious creatures.

Defeated, and knowing that they could not fight any longer, the survivors decided to build an impregnable fortress, the Citadel, where, being cryogenized, they will wait until others come to liberate them.

What happened when a vessel made an emergency landing on this somewhat known surface...

[LeBoon]

Hi,
What about having those 2 planets in synchronized opposed orbits? This way for a very long time (evolution) the other planet is behind the sun, preventing any direct observation and also early radio communications. Even the first stage of space exploration around respective home lands would not give direct knowlege of the other world.

I guess such orbits would require some tricky explaination has giant planets (jupiter like) gravity perturbation could desync orbits, but that could as well be the trigger to slowly make the 2 civilisation aware of each other. You even got the title for it : "Behind the sun"

Orbits could also be slightly different, making the 2 planets visible for 1000 years every 10000 years (I guess you can do the math on orbits to get the numbers you need), the book then explaining "cheap" travel to the other world only occurs once in a while and the 2 species descending from on common ancestor, thus explaining why they are technologically close.

Sorry for the quite messy ideas there... just found the topic interesting and wrote it on the fly...

[YNM]

Nuclear testing ? Although that will have to happen when you can see the nighttime side, at night.

Or other large explosions could do.

[MaverickSawyer]

I know someone mentioned Rocheworld already, and I second that for a darn good reason...

Big Bloop. That'd keep everyone away from the inner poles. 

[Green Baron]

6 hours ago, LeBoon said:

Hi,
What about having those 2 planets in synchronized opposed orbits? This way for a very long time (evolution) the other planet is behind the sun, preventing any direct observation and also early radio communications. Even the first stage of space exploration around respective home lands would not give direct knowlege of the other world.

I guess such orbits would require some tricky explaination has giant planets (jupiter like) gravity perturbation could desync orbits, but that could as well be the trigger to slowly make the 2 civilisation aware of each other. You even got the title for it : "Behind the sun"

Orbits could also be slightly different, making the 2 planets visible for 1000 years every 10000 years (I guess you can do the math on orbits to get the numbers you need), the book then explaining "cheap" travel to the other world only occurs once in a while and the 2 species descending from on common ancestor, thus explaining why they are technologically close.

Sorry for the quite messy ideas there... just found the topic interesting and wrote it on the fly...

The most reasonable proposal (and btw. welcome :-)) i find.

I see two things: first the orbits must be absolutely circular or the planets would peep around the sun's edge. Or they must be absolutely synchronous because of the different velocities on their respective orbits.

Second: the sun must not be too "heavy", so that light bent around it does not allow for too deep a view behind it.

This setup worked for the last few hundred years (one does not need more, powerful telescopes aren't that old yet), and then something happens, a periodical or single time constellation of other planets, that slightly changes the orbits ....

I like your idea :-)

 

Improbable imo: both civs must have developed identically during billions of years of evolution, so that they reach a state of using radio at the same time.

Edited November 13, 2018 by Green Baron

[Nuke]

how about one of the planets was in an ice age or some kind of snowball earth type event, and the inhabitants are simply living underground to stay warm. perhaps have the story take place durring the early stages of thawing as the surface of that world becomes more hospitable and the underground civilization starts moving to the surface. 

you could also have it so that the inhabitants of the frozen world were at the same tech level as the current population of the other world prior to the icing event. however the need for survival put a hault on progress for that species which had to adopt a more simple way of life due to limited resources. you could have one civilization technicaly a few hundred thousand years older than the other while still having the same tech level. the inhabitants of the warm world could have made the transition from hunter-gatherer to agricultural during the event and have similar rate of advancement to us. there may have even been some long forgotten contact between the world previously or one may have been a colony of the other. but for some reason this knowlege was either lost or not known to either world. perhaps the colony succeeded in relocating but for some forgotten calamity or generational conflict resulted in their tech and culture being lost. 

[kerbiloid]

https://phys.org/news/2014-09-alcohol-clouds-space.html

http://mentalfloss.com/article/51271/there-are-giant-clouds-alcohol-floating-space

So,

Spoiler

A small clot of a space alcohol cloud had sticked in a Lagrange point between the planets a million years ago.

Under the rains from there two populations of drunken monkeys separated by space have evolved into sapient (from time to time) beings.

They didn't see the counterpart planet because of this dark thick cloud and because they didn't care.

Once the cloud got depleted, the planet dwellers for the first time became sober, looked up and saw each other.

 

Edited November 13, 2018 by kerbiloid

[magnemoe]

How about the clouds did not disappear but you discover flight and fly above the clouds, make the main civilization on the outer side so even if they penetrated the clouds, because no stars or planets astronomy is an non issue. 
Then some flew an high attitude plane to the inside. 
Inside is mostly ocean like the pacific. 

[kerbiloid]

Reminds me of Little Big Adventure.

A planet with the hemispheres separated by a mountain ridge.

A planet with a gas layer splitting the surface into "below gas" and "above gas".

***

Maybe a volcanic smoke? When it's required, it is. When it isn't, it stops.

Btw remember that slow enormous Io volcano in Expanse.

Spoiler

 

Edited November 13, 2018 by kerbiloid

[Ultimate Steve]

2 hours ago, magnemoe said:

How about the clouds did not disappear but you discover flight and fly above the clouds, make the main civilization on the outer side so even if they penetrated the clouds, because no stars or planets astronomy is an non issue. 
Then some flew an high attitude plane to the inside. 
Inside is mostly ocean like the pacific. 

That was my lead idea, actually, I'm glad I'm not the only one who finds it reasonable!

[Racescort666]

Spoiler

2 hours ago, kerbiloid said:

Once the cloud got depleted, the planet dwellers for the first time became sober, looked up and saw each other.

 

Spoiler

Probably after recovering for the worst hangover in the universe.

On topic: the Earth-Sun L3 lagrange point is very unstable. https://map.gsfc.nasa.gov/mission/observatory_l2.html

Quote

The idea of a hidden "Planet-X" at the L3 point has been a popular topic in science fiction writing. The instability of Planet X's orbit (on a time scale of 150 years) didn't stop Hollywood from turning out classics like The Man from Planet X.

 

Edited November 13, 2018 by Racescort666
added on topic content