Need help with a planet....and other questions

[Czcibor]

So...according to this,under a pressure of 10 bars(9.86923 atm) ammonia should have a boiling point of 25 C.That should be ample for life,right?

Seems like huge margin.

Under such pressure you can also expect liquid CO2.

One more thing. You wanted a big planet:

f the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. Let us assume that building a rocket at 96% propellant (4% rocket), currently the limit for just the Shuttle External Tank, is the practical limit for launch vehicle engineering. Let us also choose hydrogen-oxygen, the most energetic chemical propellant known and currently capable of use in a human rated rocket engine. By plugging these numbers into the rocket equation, we can transform the calculated escape velocity into its equivalent planetary radius. That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport.

That was calculated for Earth composition, sure. Your ice ball would be lighter, I assume, nevertheless...

http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html

 

[KristijanT]

Under such pressure you can also expect liquid CO2.

Good thing,bad thing(or...uhm,neutral thing)? :D

One more thing. You wanted a big planet:

Well,if it would be a problem,to be honest,that could very easily change!

Your ice ball would be lighter, I assume, nevertheless...

Well,I don't imagine the planet as an ice ball...but,nevermind -- so a big(ger than Earth) planet isn't a problem,then?

 

[Czcibor]

Good thing,bad thing(or...uhm,neutral thing)? :D

Mountain glaciers of dry ice, that actually melts, flows downstream and evaporates before reaching sea level? Sounds interesting.

Well,if it would be a problem,to be honest,that could very easily change!

Well,I don't imagine the planet as an ice ball...but,nevermind -- so a big(ger than Earth) planet isn't a problem,then?

One issue. For my purposes I consider as cool building a planet that is weird and all weirdness is perfectly according to laws of physics. That civilization had to be built in different way, not because of any choice but because of environmental determinism. On the other hand when I discovered such stuff too late, it required some rewriting.

Actually big rocky planet can work. And you can be delighted that local civilization haven't sent a space rocket before invention of fusion nuclear engine. Because of dense atmosphere they may had problems to see stars at all, so they may have started creating rough astronomy as late as during their equivalent of industrial revolution.

Fits your story or not specially?

 

[KristijanT]

Actually big rocky planet can work.

Actually -- I imagined the planet as a...darkish(as I said earlier with the plants being dark to collect more light) with dark-green dots being seen across the lands from Space(that's a...well,special detail :D ),with oceans of brown liquid ammonia(it becomes brownish when it dissolves large amounts of alkali metals).

Mountain glaciers of dry ice, that actually melts, flows downstream and evaporates before reaching sea level? Sounds interesting.

Interesting,and very cool!(pun intended)

Because of dense atmosphere they may had problems to see stars at all, so they may have started creating rough astronomy as late as during their equivalent of industrial revolution.

Fits your story or not specially?

It actually fits my story nicely,and it's definitely a good idea.Now...next thing that could be adressed would be the process of getting energy.As I posted above,maybe solvated electrons that are held in the liquid ammonia could play a big part in this?

 

[Czcibor]

Actually -- I imagined the planet as a...darkish(as I said earlier with the plants being dark to collect more light) with dark-green dots being seen across the lands from Space(that's a...well,special detail :D ),with oceans of brown liquid ammonia(it becomes brownish when it dissolves large amounts of alkali metals).

Right... brown ammonia and no ice caps over oceans... (heavier, sinks)

Now...next thing that could be adressed would be the process of getting energy.As I posted above,maybe solvated electrons that are held in the liquid ammonia could play a big part in this?

This part would involve high percentage of handwavium and making stuff up. The only thing that I see here as hard fact - low amount of energy, not so densely populated environment. The rest would be creating plausible story, with very remote contact with hard data. Suggestion: leave it for later, just basing on that that you would finally need.

 

[KristijanT]

...leave it for later, just basing on that that you would finally need.

Well,what I would need is a very very basic explanation on how do the aliens get energy,really.Nothing complex or complicated,just something that could be put in some 1-3 sentences.

Other things I'll need to address: The planet's protection from its host star.On Earth,it is the ozone.On this planet?

I'll also need to create 4 other planets(yep,don't read it again,4 other planets),and I think all of them would be with a biochemistry same as Earth,some with different gravity,and of course,different creatures/environments and all other kinds of differences you can imagine.The positive stuff of this is that I won't need to have much details about the planets because the protagonist won't spend much time on them.
Nevertheless,I won't be focusing on the planets at all before I address all of the problems about the alien planet (with your great help,of course!),create a new element(s) too(they'll have much to do with the ancient alien civilization),and think of an event that will make the aliens' planet(the one we're talking about now) inhabitable -- but due to their only-recently developed(but,nonetheless,much more developed than ours because -- they're much more technologically advanced than us when they start developing it)astronomy they have little time to save themselves and end up doing the decisions that lead to the start of my story.Yep,much work to do,indeed.

Also,at this point,even though there will be much more questions(and hopefully,answers) incoming,I still want to thank you for helping.

 

[Czcibor]

Well,what I would need is a very very basic explanation on how do the aliens get energy,really.Nothing complex or complicated,just something that could be put in some 1-3 sentences.

In non-polar liquid... Hmm...
Requires as water... using some local enzyme produces hydrogen peroxide and dumps hydrogen (lost from the system)? To recover energy first decompose peroxide and later oxidize amonia?

[limited science content, water should be very popular substance especially for such frozen planet, energetically makes sense, peroxide would be frozen and treated as local lard equivalent, no idea whether it would really work]

Other things I'll need to address: The planet's protection from its host star.On Earth,it is the ozone.On this planet?

Make the star smaller:
-would give more time for evolution of those slow species
-would make the star less active in UV

I'll also need to create 4 other planets(yep,don't read it again,4 other planets),and I think all of them would be with a biochemistry same as Earth,some with different gravity,and of course,different creatures/environments and all other kinds of differences you can imagine.The positive stuff of this is that I won't need to have much details about the planets because the protagonist won't spend much time on them.
Nevertheless,I won't be focusing on the planets at all before I address all of the problems about the alien planet (with your great help,of course!),create a new element(s) too(they'll have much to do with the ancient alien civilization),and think of an event that will make the aliens' planet(the one we're talking about now) inhabitable -- but due to their only-recently developed(but,nonetheless,much more developed than ours because -- they're much more technologically advanced than us when they start developing it)astronomy they have little time to save themselves and end up doing the decisions that lead to the start of my story.Yep,much work to do,indeed.

Also,at this point,even though there will be much more questions(and hopefully,answers) incoming,I still want to thank you for helping.

Damn it. I would just feed you with planets that I use:

Amanda:
-binary system, 2/3 of its energy comes from red dwarf that it orbits in slightly above a week (tidal lock), 1/3 in from Sun sized star that is being orbited in 5 years
-terribly frozen, over 60% of surface covered with ice, on the dark side temporary appears frozen carbon dioxide
-oceans 80%
-3 atm
-the only area settled is dry, subtropical region near big rivers (yes, on ocean-ice planet you seek hot and dry place :D )

Mahdi:
-dry planet, water cover below 10% (that actually extends habitable zone, as it harder to achieve runaway greenhouse effect)
-no longer tectonic activity
-minimum axial tilt
-no moon, 14h day
-very hot, only poles are inhabitable
-effectively only one pole settled

USO:
-very young planet 2.5 bln years max
-part of oxygen actually came from water hydrolysis from UV
-already at edge of habitable zone (too hot)
-2 moons, very strong tides
-20h day
-young planet - higher content of U225 to U238 - nuclear fuel does not need enrichment
-too high UV for humans, have to hide for day

JW:
-chthonian planet orbiting white dwarf
-tidal lock
-dense, very rich in metals
-10 km of ice frozen on its dark side, equilibrium achieved because the glacier creeps back and melts
-seas of very high salinity that remain liquid in spite of temp below 0
-only rainy area in the centre is habitable

Viking:
-exomoon, one day (orbit) is 11 days
-sea cover, 70%
-one super continent, effectively uninhabitable
-only inhabitable areas are islands (inside the continent temperature jumps are lethal)
-weird season because of combination of axial tilt and elongated orbit of its gas giant

Octopus:
-4 Earth masses
-very dense atmosphere
-roughly uniform climate below, wet
-strong greenhouse effect
-only habitable areas are mountain ranges

Useful? ;)

 

[KristijanT]

While I have to thank you for posting planets you already created,and some of the information about them does give inspiration for other ideas,I got to say,that,as I have mentioned in my previous post,most of it would,in my opinion,be too unrelevant to the plot to mention! Though,the mention of binary system just reminded me to an article I have read about a planet in a quadruple star system: now that'd be cool to use!

Requires as water... using some local enzyme produces hydrogen peroxide and dumps hydrogen (lost from the system)? To recover energy first decompose peroxide and later oxidize amonia?

I didn't quite get you there though...

water should be very popular substance especially for such frozen planet

Actually -- in a reducing atmosphere such as this planet's -- water for the creatures living on the it would be exactly as acid to us.So...I don't think that water would/should be a very popular substance in this planet...

Make the star smaller:
-would give more time for evolution of those slow species
-would make the star less active in UV

Yeah,sure,though I kinda doubt that it will be enough to shield the planet.

 

[mfb]

One more thing. You wanted a big planet:

f the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. Let us assume that building a rocket at 96% propellant (4% rocket), currently the limit for just the Shuttle External Tank, is the practical limit for launch vehicle engineering. Let us also choose hydrogen-oxygen, the most energetic chemical propellant known and currently capable of use in a human rated rocket engine. By plugging these numbers into the rocket equation, we can transform the calculated escape velocity into its equivalent planetary radius. That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport.

That was calculated for Earth composition, sure. Your ice ball would be lighter, I assume, nevertheless...

It is a practical limit, not a fundamental one. That is the point of staged rockets. The payload to rocket mass ratio goes down, but it does not get impossible.Concerning lithium for fusion: even on Earth we have more lithium than we could reasonably use for tritium breeding in the near future. The hard part is the fusion reactor, not the lithium or deuterium supply.

 

[KristijanT]

So...question incoming:
What do you think about different-shaped eyes?
No,no,I don't mean different-shaped pupils,but eyes.

 

[Loren]

So...question incoming:
What do you think about different-shaped eyes?
No,no,I don't mean different-shaped pupils,but eyes.

Why look at what nature already provides?

You can extrapolate from there, but the further you detour from what is proven the more likely you will find errors in your proposals.

 

[Czcibor]

So...question incoming:
What do you think about different-shaped eyes?
No,no,I don't mean different-shaped pupils,but eyes.

What for?

I don't see special source of difference here (except maybe a bit less light, a slightly bigger eyes advisable)?

You need some weird stuff for cool factor?

 

[Loren]

What for?

I don't see special source of difference here (except maybe a bit less light, a slightly bigger eyes advisable)?

You need some weird stuff for cool factor?

Larger eyes are interesting. In one of my books the population genetically modified their eyes to be slightly larger to give their faces a more pedomorphic trait. They simply saw it as a more sexually desirable feature and adopted it as the norm.

So, in some instances features can be artificially enhanced, deviating from the evolutionary norm.

 

[Czcibor]

Larger eyes are interesting. In one of my books the population genetically modified their eyes to be slightly larger to give their faces a more pedomorphic trait. They simply saw it as a more sexually desirable feature and adopted it as the norm.

So, in some instances features can be artificially enhanced, deviating from the evolutionary norm.

And can make the whole planet cute/ turn local population into anime characters. ;)

More seriously, making eyes interesting:
-compound eyes - not specially, may give some minor advantages if the creature used to be a prey;
-different wave sensitivity - maybe - if the star is dimmer, then should see near infra red and can sacrifice violet visibility (drawback - don't visible directly from character, only visible from colors of artificial objects)

 

[KristijanT]

You need some weird stuff for cool factor?

Haha,nope! For that matter,I actually have a weird enough alien -- I just though that,it's a totally different world,so,there is a good chance that most of the creatures will be very different,eh? Though,of course,I could just put same-looking eyes,and just free myself of complications,but just wanted to put this up here before I do so to have a look at some opinions,and,well,maybe to decide otherwise.

 

[Czcibor]

Haha,nope! For that matter,I actually have a weird enough alien -- I just though that,it's a totally different world,so,there is a good chance that most of the creatures will be very different,eh? Though,of course,I could just put same-looking eyes,and just free myself of complications,but just wanted to put this up here before I do so to have a look at some opinions,and,well,maybe to decide otherwise.

You can already have weird creatures without such... cool environment. ;) Superorganisms, symbiotic organisms, non-human shape... Right now I don't see extra features...

One idea... you have water ice beneath ammonia, right? What about burrowing creatures that melt their way through ice? (for some local animals)

 

[Guapa]

Need to give advance math to childern in an insight playful matter, too!

 

[KristijanT]

One idea... you have water ice beneath ammonia, right? What about burrowing creatures that melt their way through ice? (for some local animals)

Yeah,certainly a good idea.BUT...to note: I won't really create a big number of species that would live on the planet.In fact,other than the intelligent aliens on the planet,I plan to create a predator,that would be a kind of a...nemesis to the intelligent alien race during the ages when they were...well,not so intelligent(basically,like our Stone Age),some cool-looking unique plants and maybe some few more (unique,again ) animal species (all of which,I won't go through creating much details,just some basic stuff).

Though,also to note,I've already created a physical look of the intelligent alien race,but it is another area that I need help in,which is...

What event,do you think,would leave that (much more than us) intelligent with little to no time to leave their planet in order to save themselves from extinction?
Obviously,it would have to be an event that would be hard to detect in the right time,but I think the...late astronomical development may explain this...?
Damn,kinda feel like nitpicking,but that's the way it is...

 

[Czcibor]

Yeah,certainly a good idea.BUT...to note: I won't really create a big number of species that would live on the planet.In fact,other than the intelligent aliens on the planet,I plan to create a predator,that would be a kind of a...nemesis to the intelligent alien race during the ages when they were...well,not so intelligent(basically,like our Stone Age),some cool-looking unique plants and maybe some few more (unique,again ) animal species (all of which,I won't go through creating much details,just some basic stuff).

Big predator would kill a lot, but still would be quite plenty left (land creature - so sea and flying creatures are mostly left unmolested)Though,also to note,I've already created a physical look of the intelligent alien race,but it is another area that I need help in,which is...

What event,do you think,would leave that (much more than us) intelligent with little to no time to leave their planet in order to save themselves from extinction?
Obviously,it would have to be an event that would be hard to detect in the right time,but I think the...late astronomical development may explain this...?

Ideas:
1) Maybe an imminent collision:
https://en.wikipedia.org/wiki/Phobos_(moon)#Predicted_destruction
From the planet it would be obvious, for any far observer - not so easy.

2)Small rouge planet on a collision course.

3) Big (more massive than Jupiter) passing by rouge planet that would destabilize the orbit and after a few violent swings put a planet into habitable zone for carbon based life :D

Damn,kinda feel like nitpicking,but that's the way it is...

Don't worry. When I started creating my stuff, from dessert planet with habitable pools I moved to an icy, tidal locked planet. And the political system from a bit improved democracy get serious Brave new world totalitarianism features...

 

[Loren]

If you want an extinction event you might consider a relativistic mass (either natural or not).

For example, Deimos, one of the moons of Mars is just 12.6 km in diameter. It's mass is 2 * 10^15 kg.

At 9/10 C the resultant energy would be enough to fragment Earth into tiny pieces.

The calculations go like this. For Earth you must calculate the binding gravitational energy of the planet (about 2 * 10^32 Joules).

Next, calculate the relativistic kinetic energy of your mass:

Ke = y • mc^2, where y = relativistic gamma = 1/ sort(1- (v^2/C^2))

At v = 90% C, m = 2 • 10^15 kg ==> 2.3 • 10^32 Joules

At 9/10 C you won't have much time to react to such a small body.

Obviously, you don't need to smash a planet to bits. Enough energy to create a world-wide firestorm would do that without fragmenting a planet.

Another natural source is a supernova. The resulting gamma radiation would quickly sterilize a planet if it was close enough ( a few light years) and without warning since the radiation would arrive at C. That assumes there was no real notice of the star going supernova, so you have to be blind to the signs.

Do a search for cosmological planet extinction events and get some ideas.

 

[Czcibor]

I didn't quite get you there though...

2H₂O -> H₂O₂ + H₂

If you want an extinction event you might consider a relativistic mass (either natural or not).

For example, Deimos, one of the moons of Mars is just 12.6 km in diameter. It's mass is 2 * 10^15 kg.

At 9/10 C the resultant energy would be enough to fragment Earth into tiny pieces.

The calculations go like this. For Earth you must calculate the binding gravitational energy of the planet (about 2 * 10^32 Joules).

Next, calculate the relativistic kinetic energy of your mass:

Ke = y • mc^2, where y = relativistic gamma = 1/ sort(1- (v^2/C^2))

At v = 90% C, m = 2 • 10^15 kg ==> 2.3 • 10^32 Joules

At 9/10 C you won't have much time to react to such a small body.

Obviously, you don't need to smash a planet to bits. Enough energy to create a world-wide firestorm would do that without fragmenting a planet.

Another natural source is a supernova. The resulting gamma radiation would quickly sterilize a planet if it was close enough ( a few light years) and without warning since the radiation would arrive at C. That assumes there was no real notice of the star going supernova, so you have to be blind to the signs.

Do a search for cosmological planet extinction events and get some ideas.

I know about hypervolocity stars, but its still a few of degrees of magnitude to slow for what you suggest.

 

[BiGyElLoWhAt]

https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/microbial-ecology-16/nutrient-cycles-195/the-nitrogen-cycle-984-5464/
Here's information on the Nitrogen cycle, I know you're looking for the Boron cycle to determine a possible respiratory equivalent, but...

Anyways, with respect to your Boron situation, I also agree with letting it "go away", as we don't even know how a lot of our stuff here came to be. Yea, asteroids, or whatever, but if you can't observe due to a dense atmosphere, you can't get anything but the biggest of asteroids through that atmosphere, they would burn up.

How about this, if you really want a reason for dense boron:
Place the planet orbiting a star close to the center of the galaxy, with a galactic black hole in the center. You get a higher probability of bigger stars, which gives you a higher probability of supernovas occurring, which gives you a reasonable probability to find boron near the galactic center. There could be a star with high boron density across the galactic black hole, which upon self destructing, ejected boron in all directions. Then the boron gets flung around the black hole on either side, and populates this region of space with boron.
I think it sounds plausible.

 

[Czcibor]

https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/microbial-ecology-16/nutrient-cycles-195/the-nitrogen-cycle-984-5464/
Here's information on the Nitrogen cycle, I know you're looking for the Boron cycle to determine a possible respiratory equivalent, but...

Anyways, with respect to your Boron situation, I also agree with letting it "go away", as we don't even know how a lot of our stuff here came to be. Yea, asteroids, or whatever, but if you can't observe due to a dense atmosphere, you can't get anything but the biggest of asteroids through that atmosphere, they would burn up.

How about this, if you really want a reason for dense boron:
Place the planet orbiting a star close to the center of the galaxy, with a galactic black hole in the center. You get a higher probability of bigger stars, which gives you a higher probability of supernovas occurring, which gives you a reasonable probability to find boron near the galactic center. There could be a star with high boron density across the galactic black hole, which upon self destructing, ejected boron in all directions. Then the boron gets flung around the black hole on either side, and populates this region of space with boron.
I think it sounds plausible.

[still wondering about what for nitrogen cycle can be used in this case...]

How plausible is boron star? I don't know about boron, but in case of lithium it is being used as a marker to check whether there was any nuclear reaction on a brown dwarf. If there were, than the lithium would be mostly gone.

 

[mfb]

Another natural source is a supernova. The resulting gamma radiation would quickly sterilize a planet if it was close enough ( a few light years) and without warning since the radiation would arrive at C. That assumes there was no real notice of the star going supernova, so you have to be blind to the signs.

The stellar surface doesn't change so quickly, but the interior does. This paper suggests we can get days to hundreds of years of warning time for stars in relevant distances (hundreds of light years), depending on the quality of neutrino detectors. Nice for science fiction: you can adjust the warning time as you like.

 

[BiGyElLoWhAt]

[still wondering about what for nitrogen cycle can be used in this case...]

How plausible is boron star? I don't know about boron, but in case of lithium it is being used as a marker to check whether there was any nuclear reaction on a brown dwarf. If there were, than the lithium would be mostly gone.

Well, I saw something previously in respect to B-N chemistry, so I could see some use for it, but maybe not.

From what I've gathered, fusion is the most plausible way to get Boron, at least in any quantity. A star of the appropriate size, I'm sure, could collapse into a supernova, and also have a reasonable Boron concentration. This could happen several times, if necessary, supernovas all over the place.

I'm not suggesting that all or even most of the star is Boron, just that it's in a sufficient quantity to be able to seed a planet with copious amounts.

 

[KristijanT]

Big (more massive than Jupiter) passing by rouge planet that would destabilize the orbit and after a few violent swings put a planet into habitable zone for carbon based life :D

That,I guess,seems cool,though,I doubt they wouldn't discover it until it's too late(?).

Anyways, with respect to your Boron situation, I also agree with letting it "go away", as we don't even know how a lot of our stuff here came to be.

That's what it's probably going to be.Though,the black hole idea seems very interesting too.It may be a combination of both though( not knowing how it exactly happened,but having this theory that you propose,for example?).

The stellar surface doesn't change so quickly, but the interior does. This paper suggests we can get days to hundreds of years of warning time for stars in relevant distances (hundreds of light years), depending on the quality of neutrino detectors. Nice for science fiction: you can adjust the warning time as you like.

What about a warning time of...few hours?

 

[mfb]

If your species doesn't have large neutrino detectors, you easily get a few hours. We had that for SN1987A, 150 thousand light years away. Three hours before the visible light from the explosion reached us about 30 neutrinos were detected here on Earth with the detectors of 1987. Scale this to 100 light years distance and we would have received 30 millions, probably saturating some detectors. Even small detectors (small for neutrino physics) can measure such an intense flux.
The warning time doesn't depend on distance here as neutrinos and light are (nearly) at the same speed.

 

[Czcibor]

That,I guess,seems cool,though,I doubt they wouldn't discover it until it's too late(?).

Depends. What's their tech level? Which devices they have?

 

[KristijanT]

Depends. What's their tech level? Which devices they have?

Their tech level would be: hugely higher than ours.Devices? Well,a device that can basically store the whole civilization into a virtual world(which is by the way,a prototype -- so,then,a not finished device) -- which is,I know,hugely fictional,but I don't really plan on doing a ultra-hard sci-fi.More of a...between soft and hard sci-fi.That's why I have a hard time thinking of an (cosmological,preferably) event that will leave them little time to evacuate(into the device I just mentioned -- and trigger the events that lead to the beginning of the story.)

But it's all kinda unique,because,as we discussed earlier,their astronomy isn't very much developed,so...that's something to use,I guess?

 

[Czcibor]

Their tech level would be: hugely higher than ours.Devices? Well,a device that can basically store the whole civilization into a virtual world(which is by the way,a prototype -- so,then,a not finished device) -- which is,I know,hugely fictional,but I don't really plan on doing a ultra-hard sci-fi.More of a...between soft and hard sci-fi.That's why I have a hard time thinking of an (cosmological,preferably) event that will leave them little time to evacuate(into the device I just mentioned -- and trigger the events that lead to the beginning of the story.)

But it's all kinda unique,because,as we discussed earlier,their astronomy isn't very much developed,so...that's something to use,I guess?

Damn...
At such moment their starting conditions would no longer limit their space technology (in the same way as in ancient times northern part of North America or northern Europe were not good place to start a civilization... From times of industrial revolution it no longer matter...).

Attack by a different civilization using:
https://en.wikipedia.org/wiki/Relativistic_kill_vehicle

?

Other approach... What if they launch some experiment that goes really bad?
Like a working model of a black hole... ? (needs something better, I know...)

 

[KristijanT]

Though -- I forgot to mention.Actually,the civilization is -- as I said,yes,with a hugely higher tech level than ours...BUT: the reason for this is only a recent breakthrough(some 40-60 human years) discovery -- which,yep,you guessed it,helped them vastly improve their technology.Before that -- they were,well,yeah,more advanced than us(for example,knew of Earth,could travel much bigger distances -- not galactically huge,or traveling 100 LY and getting back in a day,but,for example,travelling 10+ LY and getting back for them would be like sending a manned mission to Mars,and getting it back for us).

 

[KristijanT]

Other approach... What if they launch some experiment that goes really bad?
Like a working model of a black hole... ? (needs something better, I know...)

Yeah,seems good,but,a black hole would,I guess,give them too little time,eh?

EDIT:

And,I also want to avoid other (existing in the present) civilizations because I don't want a space opera as a result.

 

[mfb]

A tiny black hole would need some time to destroy a planet, where the time depends on the initial size of the black hole. It would take even longer with a star.

 

[SlowThinker]

Interesting theme. Let me try to add some answers... I'm not a physicist though, some "facts" may be false.
1) Why is there boron?
Near the galactic center, the stars form faster and bigger, so your system could be a 3rd generation rather than 2nd like ours, thus having more heavy elements. That still makes C&N&O more abundant than B though... Maybe there is a shell rich with boron in a supernova explosion, and your planet formed just in the right spot. In fact, two star systems formed. The other is circling the galactic core at a slightly different speed (as its distance is different), and now it's just where you need it
2) The event
As there are more stars near the galactic center, another supernova explosion is the obvious candidate. Or a gamma ray burst. Perhaps the planet has already been hit and now its wildlife is collapsing? You don't even need astronomy for that.
3) The advancement
Obviously, the development of generic artificial intelligence will have a tremendous impact on all of science... and goes well together with a supercomputer capable of storing the population of a planet.
Another choice would be fusion power. Perhaps energy is the scarce resource on the planet, and with fusion-powered farms, the population is growing rapidly, having more scientists etc. Does not play well with wildlife collapse from (2) though, they just would not care.
4) Eyes
Perhaps many tiny eyes would be embedded in skin, adapted from leaves? After all, not being able to photosyntesize is a huge disadvantage...

But truth is, you should be the one coming with ideas...

 

[KristijanT]

1) Why is there boron?
Near the galactic center, the stars form faster and bigger, so your system could be a 3rd generation rather than 2nd like ours, thus having more heavy elements. That still makes C&N&O more abundant than B though... Maybe there is a shell rich with boron in a supernova explosion, and your planet formed just in the right spot. In fact, two star systems formed. The other is circling the galactic core at a slightly different speed (as its distance is different), and now it's just where you need it

First,thank you for your post.I've already addressed this question(not knowing what exactly happened,but presenting some theories about it),but,nevertheless,your idea added a bit more to it(another theory),so,thanks.

2) The event
As there are more stars near the galactic center, another supernova explosion is the obvious candidate. Or a gamma ray burst. Perhaps the planet has already been hit and now its wildlife is collapsing? You don't even need astronomy for that.

Truth to be told,it's not as much hard to think of an event that will destroy the planet as it is to think of an event that will destroy the planet and plus leave such an advanced civilization with little time to save themselves.

3) The advancement
Obviously, the development of generic artificial intelligence will have a tremendous impact on all of science... and goes well together with a supercomputer capable of storing the population of a planet.
Another choice would be fusion power. Perhaps energy is the scarce resource on the planet, and with fusion-powered farms, the population is growing rapidly, having more scientists etc. Does not play well with wildlife collapse from (2) though, they just would not care.

Same as for 1),I've got this solved already(by,as I said some couple of posts ago,introducing some really fictional stuff).

4) Eyes
Perhaps many tiny eyes would be embedded in skin, adapted from leaves? After all, not being able to photosyntesize is a huge disadvantage...

Thanks for the idea,although I have it addressed too

But truth is, you should be the one coming with ideas...

To a certain degree,you are right.I should be the one coming with ideas.And,mostly,I am.
I'm only asking for help about things I'm scratching my head over(an example is the event that gets the planet to extinction,with the advanced civilization thus having little time to respond) or when I want some opinions from other people about certain things(the eyes and other senses being an example).