Strange space related question.

[Traab]

Ok, here we go. This is a question about relative sizes. In some anime like dragonball we see characters who are supposed to be able to destroy the solar system in a single blast. Lets say you are standing at the outer (or inner, im not that picky) edge of our own solar system, and you want to send out a beam to hit all the planets at once. How wide would this beam have to be in circumference to tag all the planets at once no matter where they are in relative orbits to each other? I wasnt honestly sure how to figure this one out or google it. Do I need to just know the full orbital path of the most distant planet? Is it a lower number than that?

[Fyraltari]

Ok, here we go. This is a question about relative sizes. In some anime like dragonball we see characters who are supposed to be able to destroy the solar system in a single blast. Lets say you are standing at the outer (or inner, im not that picky) edge of our own solar system, and you want to send out a beam to hit all the planets at once. How wide would this beam have to be in circumference to tag all the planets at once no matter where they are in relative orbits to each other? I wasnt honestly sure how to figure this one out or google it. Do I need to just know the full orbital path of the most distant planet? Is it a lower number than that?

We are talking about a perfectly cylindrical beam aimed at the sun yes? Then to be sure you tocuh every planet no mtter where they are, you would need a beam with a radius equal to the maximum distance between the Sun and Neptune (since all planets are somewhere closer to the Sun than Neptune), that is 4, 537, 000, 000 km, for a total width of 9, 074, 00, 000 km (or about 60 times the distance Earth-Sun).

And if you muuuuuuust include Pluto as a planet, that's a 7, 375, 927, 931km radius for a 14, 751, 855, 862km width

But really if you want to destroy the Solar System, just blow the Sun up and let it do the work.

[Traab]

We are talking about a perfectly cylindrical beam aimed at the sun yes? Then to be sure you tocuh every planet no mtter where they are, you would need a beam with a radius equal to the maximum distance between the Sun and Neptune (since all planets are somewhere closer to the Sun than Neptune), that is 4, 537, 000, 000 km, for a total width of 9, 074, 00, 000 km (or about 60 times the distance Earth-Sun).

And if you muuuuuuust include Pluto as a planet, that's a 7, 375, 927, 931km radius for a 14, 751, 855, 862km width

But really if you want to destroy the Solar System, just blow the Sun up and let it do the work.

Oh ok, so totally doable then. I figured it was going to be something like the entire diameter of the last planets orbital path but I wasnt sure if it was going to be more complicated than that as I swear its never that simple. Dear god thats SO MUCH WASTED ENERGY! Like 99.99999999% of it wont be hitting ANYTHING just to make sure all planets do get tagged by the destructobeam. Also, blowing up the sun. WOULD that destroy the solar system? Or just a few of the closer planets, leaving the rest to drift into eternal frozen darkness? Because that just feels like a sloppy way to "destroy" a solar system lol.

[Fyraltari]

Oh ok, so totally doable then. I figured it was going to be something like the entire diameter of the last planets orbital path but I wasnt sure if it was going to be more complicated than that as I swear its never that simple. Dear god thats SO MUCH WASTED ENERGY! Like 99.99999999% of it wont be hitting ANYTHING just to make sure all planets do get tagged by the destructobeam. Also, blowing up the sun. WOULD that destroy the solar system? Or just a few of the closer planets, leaving the rest to drift into eternal frozen darkness? Because that just feels like a sloppy way to "destroy" a solar system lol.

I mean there’s no reason it would need to be wider than that and if it wasn’t that wide then you could miss one.

I mean once the sun is blown up there is no longer a solar system to speak of, just a bunch rogue planetoids. If you want to actually create an explosion big enough to break the structural bonds of every planet then I don’t think blowing the sun would be enough. At least not in the sense of ‘trigerring a reaction within the star itself so that its own energy amounts for most of the destructive force unleashed’. I’m like 75% sure our sun can’t go supernova on its own for example.

But really just blowing up everything lacks style.

If you have enough energy to create the destructive beam we discussed however you may have the means to just make an artificial black hole where our sun is. That should do the trick.

[jayem]

From the top it will be between Neptune's orbital diameter (because it needs to contain the sun and Neptune)
And Neptune+Uranus's orbital diameter.

From the elliptic plane (if it were perfect) then the planets might line up. Even if you just get Neptune and Uranus lined up that might cut the beam to less than 10AU.

(It would probably be vastly more efficient to have a beam target each planet individually though, at that point there's also less chance of collateral)

[Traab]

I mean there’s no reason it would need to be wider than that and if it wasn’t that wide then you could miss one.

I mean once the sun is blown up there is no longer a solar system to speak of, just a bunch rogue planetoids. If you want to actually create an explosion big enough to break the structural bonds of every planet then I don’t think blowing the sun would be enough. At least not in the sense of ‘trigerring a reaction within the star itself so that its own energy amounts for most of the destructive force unleashed’. I’m like 75% sure our sun can’t go supernova on its own for example.

But really just blowing up everything lacks style.

If you have enough energy to create the destructive beam we discussed however you may have the means to just make an artificial black hole where our sun is. That should do the trick.

Heh yeah, but like I said, while destroying the sun would basically dispel the solar system it feels cheap to really call that destroying it. Certainly less of a punctuation mark than a beam of ravening energy that obliterates every single planet including the sun from one side of the solar system to the other.

[Fyraltari]

From the top it will be between Neptune's orbital diameter (because it needs to contain the sun and Neptune)
And Neptune+Uranus's orbital diameter.

From the elliptic plane (if it were perfect) then the planets might line up. Even if you just get Neptune and Uranus lined up that might cut the beam to less than 10AU.

(It would probably be vastly more efficient to have a beam target each planet individually though, at that point there's also less chance of collateral)

Well the question was one beam that would work wherever the planets are in the system. Of course if you wait for them to line up, it's easier.

Heh yeah, but like I said, while destroying the sun would basically dispel the solar system it feels cheap to really call that destroying it. Certainly less of a punctuation mark than a beam of ravening energy that obliterates every single planet including the sun from one side of the solar system to the other.

Have you read The Dark Forest by Liu Cixin?

Spoiler

Show

One man plans to threaten the Solar system by using a whole bunch of nuclear bombs to knowk Mercury out of orbit o that it would fall into the sun, which would eject enough gas to slow down Venus until it too falls into the sun ejecting enough gas to slow down the Earth until it too falls into the sun ejecting enough gas to slow down Mars until it too falls into the sun ejecting enough gas to slow down Jupiter making it a hot Jupiter. Another guy tricks an alien civilization (implied to be at least a type II on the Kardashev scale) into throwing an object at near light-speed into the core of a star disrupting and destroying it.

While not exactly system-destroying these methods are impressive when you look at the (enery spent)/(destruction caused) ratio.

You could also use the biggest bomb ever.

[Radar]

Heh yeah, but like I said, while destroying the sun would basically dispel the solar system it feels cheap to really call that destroying it. Certainly less of a punctuation mark than a beam of ravening energy that obliterates every single planet including the sun from one side of the solar system to the other.

Now if you force the core of a star to collapse into a black hole you also force it go nova pretty hard. Supernovas producing black holes might be the brightest objects ever observed and the energy outburst could pretty much wipe the solar system clean and sterilise a big chunk of the neighbouring star systems as well. If you have enough power to pull such feats, then condensing the sun and letting it explode violently might be the way to go.

[Anymage]

Now if you force the core of a star to collapse into a black hole you also force it go nova pretty hard. Supernovas producing black holes might be the brightest objects ever observed and the energy outburst could pretty much wipe the solar system clean and sterilise a big chunk of the neighbouring star systems as well. If you have enough power to pull such feats, then condensing the sun and letting it explode violently might be the way to go.

This might also be the most anime way to go about the process. Channel a beam with an energy content of roughly twice the sun's mass (ideally more) straight into it, watch it blow up spectacularly and take out at least the inner planets while scouring the outer ones clean. The remaining pulsar is a cool visual after all is said and done.

It might be different if you're standing outside the solar system. (Although these cases are quickly unscientific on their own, since the scales of even the most convenient planetary alignment will dwarf anything comprehensible on a human scale.) But if you're standing on a planet it's most likely closer to the center of the system. Instead of scything your beam to hit first the innermost stuff and then the outermost stuff, charging up the bit in the center and having it go boom dramatically sounds like better spectacle to me.

[NichG]

If we want to do this in a way that could possibly still fly in a hard sci-fi novel (despite being about anime characters punching out a solar system), then rather than doing it via shooting a beam of energy, it would make more sense to say that the character nucleates a region of vacuum with different physics, which then expands at the speed of light to cause everything in its wake to fall apart or re-adjust. That way we don't have to worry about why a character who can produce enough energy to make a black hole isn't already a walking black hole themselves - it's basically saying 'the energy was already there, because the vacuum is metastable, and the character just does something to bring that out'.

Of course, the problem is that if this new vacuum is more stable than the normal universe, there's no reason for the blast to have a finite radius. So you'd need the specific interactions between the new set of physical constants and the old ones to have a peculiar energy function - one with negative surface energy, positive volume energy, and something keeping the boundary from roughening - so that you'd get a finite-sized bubble of new physics at the end of the blast, so that the bubble remains spherical rather than turning into a foam with huge amounts of surface, and so that you don't get an eternally expanding wave. Or you need it to somehow be dynamically stabilized, but doing this with dynamics again raises the question of why the energy inputs to the process aren't already just creating black holes.

In a setting where this is possible, it seems like it would actually require a high degree of control to make it so that one's blasts only destroyed a solar system rather than (slowly) destroying the entire universe - which would require less fine-tuning.

[factotum]

(It would probably be vastly more efficient to have a beam target each planet individually though, at that point there's also less chance of collateral)

You're literally trying to blow up the entire solar system, I don't think "collateral damage" is something you really need to worry about.

[Lord Torath]

If you can completely blow away the sun's core you'll get a massive explosion that will incinerate the inner planets, scour the outer planets, and then send them all screaming off in different directions. The sun will be completely gone, so there's nothing holding them in orbit. Plus you will freeze them all after burning them all.

Jupiter, which doesn't really have a discrete core, could be blown away into nothing, while to cores of the other outer planets might remain intact while their atmospheres are stripped away.

[gomipile]

If we want to do this in a way that could possibly still fly in a hard sci-fi novel (despite being about anime characters punching out a solar system), then rather than doing it via shooting a beam of energy, it would make more sense to say that the character nucleates a region of vacuum with different physics, which then expands at the speed of light to cause everything in its wake to fall apart or re-adjust. That way we don't have to worry about why a character who can produce enough energy to make a black hole isn't already a walking black hole themselves - it's basically saying 'the energy was already there, because the vacuum is metastable, and the character just does something to bring that out'.

Of course, the problem is that if this new vacuum is more stable than the normal universe, there's no reason for the blast to have a finite radius. So you'd need the specific interactions between the new set of physical constants and the old ones to have a peculiar energy function - one with negative surface energy, positive volume energy, and something keeping the boundary from roughening - so that you'd get a finite-sized bubble of new physics at the end of the blast, so that the bubble remains spherical rather than turning into a foam with huge amounts of surface, and so that you don't get an eternally expanding wave. Or you need it to somehow be dynamically stabilized, but doing this with dynamics again raises the question of why the energy inputs to the process aren't already just creating black holes.

In a setting where this is possible, it seems like it would actually require a high degree of control to make it so that one's blasts only destroyed a solar system rather than (slowly) destroying the entire universe - which would require less fine-tuning.

Someone might have read Schild's Ladder by Greg Egan.

[Bohandas]

We are talking about a perfectly cylindrical beam aimed at the sun yes? Then to be sure you tocuh every planet no mtter where they are, you would need a beam with a radius equal to the maximum distance between the Sun and Neptune (since all planets are somewhere closer to the Sun than Neptune), that is 4, 537, 000, 000 km, for a total width of 9, 074, 00, 000 km (or about 60 times the distance Earth-Sun).

More precisely it would have to have a diameter equal to the maximum distance between the sun and Neptune plus the maximum distance between the sun and Uranus

[Fyraltari]

More precisely it would have to have a diameter equal to the maximum distance between the sun and Neptune plus the maximum distance between the sun and Uranus

Wrong. Neptune is farther away from the Sun than Uranus. Even if Neptune and Uranus were at opposite ends of the system on a straight line directly perpendicular to the beam it would engulf both.

In other words, there are no planets on the solar system that are as far away as the sum of the Uranus-Sun and Neptune-sun distances.

EDIT: Sorry I confused radius and diamaeter. It's still wrong though, since that would be a radius equal to the mean of max (Sun-Neptune) and max(Sun-Uranus) therefore inferior to max(Sun-Neptune) which would mean no guarantee of hitting Neptune.

[Bohandas]

Wrong. Neptune is farther is farther away from the Sun than Uranus. Even if Neptune and Uranus were at opposite ends of the system on a straight line directly perpendicular to the beam it would engulf both.

In other words, there are no planets on the solar system that are as far away as the sum of the Uranus-Sun and Neptune-sun distances.

The one I was responding to specified a radius that was too large. Under no circumstances does the radius need to be the entire distance from the sun to the outer limit of neptune's orbit because under no circumstance can there be a planet that far away on both sides of the sun (unless we count dwarf planets, in which case the radius and diameter must be much larger). The radius would have to be one half the furthest distance to neptune plus one half the furthest distance to uranus (or in other words the diameter would equal the full distance to one plus the full distance to the other) because Neptune can't be on both sides of the sun at once. If Neptune is on one side then the furthest out a (full) planet can be on the opposite side is the orbit of Uranus.

EDIT:
The key to the matter is that the beam does not have to be centered on the sun

[Fyraltari]

The key to the matter is that the beam does not have to be centered on the sun

Yes but if if you are not aiming at the sun, then in order to know where to aim you'd need to know the current positions of the planets and if you have that data then what you need to do is find the two planets furthest away from each other and aim a beam with a radius of half that distance towards the midpoint of the straight line between the two.

EDIT: Wait, a larger radius than that, there's an overlap between the two spheres centerd around each planet with a radius equal the distance between said planet. I'm pretty sure there's a way to figure out the max width of that overlap, but I can't remmber it right now

[Radar]

Someone might have read Schild's Ladder by Greg Egan.

The concept of physics-changing civilizations was explored by other authors as well. Lem in "A Perfect Vacuum" (collection of reviews of fictional books) does play around with the idea that the Fermi paradox and most importantly the laws of physics as we know them are a results of a game-theoretical approach to adjusting the universe by older and more advanced civilizations. Not sure, how difficult it would be to get the book itself, but it is worth it.

[JT]

Yes but if if you are not aiming at the sun, then in order to know where to aim you'd need to know the current positions of the planets and if you have that data then what you need to do is find the two planets furthest away from each other and aim a beam with a radius of half that distance towards the midpoint of the straight line between the two.

EDIT: Wait, a larger radius than that, there's an overlap between the two spheres centerd around each planet with a radius equal the distance between said planet. I'm pretty sure there's a way to figure out the max width of that overlap, but I can't remmber it right now

Take the triangle formed by the three outer planets (S-U-N) and use the smallest of the three “heights” of that triangle. The sun and five other planets (sorry Pluto) will all be inside the triangle.

Although... why is this evil villain leaving the Oort Cloud intact???

[DavidSh]

Take the triangle formed by the three outer planets (S-U-N) and use the smallest of the three “heights” of that triangle. The sun and five other planets (sorry Pluto) will all be inside the triangle.

Although... why is this evil villain leaving the Oort Cloud intact???

Probably wants to avoid destroying Eris and Dysnomia, for reasons having to do with their names.

[Radar]

Take the triangle formed by the three outer planets (S-U-N) and use the smallest of the three “heights” of that triangle. The sun and five other planets (sorry Pluto) will all be inside the triangle.

Although... why is this evil villain leaving the Oort Cloud intact???

He needs a place to chill and watch the fireworks?

[Lvl 2 Expert]

Oh ok, so totally doable then.

O sure, that beam is only about ten light hours wide. In other words, if the base of that beam spawns instantly and the front of that beam is traveling at the speed of light you'd need to keep pushing it for ten hours before it's just as long as it is wide. So it's really less of a beam and more of a disk.

[Traab]

O sure, that beam is only about ten light hours wide. In other words, if the base of that beam spawns instantly and the front of that beam is traveling at the speed of light you'd need to keep pushing it for ten hours before it's just as long as it is wide. So it's really less of a beam and more of a disk.

Now for the important question, would a flat plane be sufficient to nail all the planets? Or would you need a basic cube or rectangle of energy to hit all the planets? I know about the ecliptic plane, but I am not sure just how rigid it is adhered to by the orbiting planets. Could a 2d sheet of energy hit all the planets at once? Or would it need to be a certain depth to get all of them at once?

[farothel]

Well the question was one beam that would work wherever the planets are in the system. Of course if you wait for them to line up, it's easier.

you don't have to wait for them to line up. If you can pick your spot, you can make sure that, while they might not perfectly line up, you can reduce the diameter of the beam significantly.

[Fyraltari]

O sure, that beam is only about ten light hours wide. In other words, if the base of that beam spawns instantly and the front of that beam is traveling at the speed of light you'd need to keep pushing it for ten hours before it's just as long as it is wide. So it's really less of a beam and more of a disk.

You don't hear about that often but total stellar anihilation is really tiring on the arms.

Now for the important question, would a flat plane be sufficient to nail all the planets? Or would you need a basic cube or rectangle of energy to hit all the planets? I know about the ecliptic plane, but I am not sure just how rigid it is adhered to by the orbiting planets. Could a 2d sheet of energy hit all the planets at once? Or would it need to be a certain depth to get all of them at once?

Define "at once". A 2d plane large enough and moving perpendically towards the sun (while accompanying the sun's own motion) would touch everything in the solar system in one go.

All eight planets are within 10° of the ecliptic plane. Dwarf planets are further awy but still top at 44° with Eris.

[Traab]

You don't hear about that often but total stellar anihilation is really tiring on the arms.


Define "at once". A 2d plane large enough and moving perpendically towards the sun (while accompanying the sun's own motion) would touch everything in the solar system in one go.

All eight planets are within 10° of the ecliptic plane. Dwarf planets are further awy but still top at 44° with Eris.

By at once I mean with a single shot. We already know how wide the beam has to be to reach all the planets no matter where they are in orbit, now for how thick the beam has to be to connect with all of them in that one shot. I wasnt sure how exact and firm the ecliptic plane really is as a few degrees difference at those distances adds up to quite a bit right? Would a single razor thin line of energy 10 light hours wide, hit all the planets while going in a straight line? Or would it need to move around or be significantly thicker to connect with all of them.

[Fyraltari]

By at once I mean with a single shot. We already know how wide the beam has to be to reach all the planets no matter where they are in orbit, now for how thick the beam has to be to connect with all of them in that one shot. I wasnt sure how exact and firm the ecliptic plane really is as a few degrees difference at those distances adds up to quite a bit right? Would a single razor thin line of energy 10 light hours wide, hit all the planets while going in a straight line? Or would it need to move around or be significantly thicker to connect with all of them.

I mean, you send the razor thick line that's cicrula and system-solar wide and it doesn't need to be thick, it will reach everything eventually.

[Traab]

I mean, you send the razor thick line that's cicrula and system-solar wide and it doesn't need to be thick, it will reach everything eventually.

What im kinda asking is, if you took the planets and placed them on a flat surface setup exactly as they would appear in space, ie sun in the middle, each planet placed where it currently is in orbit in relation to each other, would some be floating above the table while some are underneath it? Or would you have them all sitting close enough to the same height as each other that this razor thin wave of energy moving across the surface would fly in a straight line and connect with them all? Maybe a different visualization. Here you stand, Fyraltari, destroyer of galaxies. You have found a solar system you want to destroy. Standing behind neptune and looking at the sun, your magical miracle vision allows you to see all the planets in the solar system at once. Are all the planets level with your vision? Is it a straight shot to hit them all at once? Or does the attack need to be more of a cube than a sheet of paper to connect with everything?

[Fyraltari]

What im kinda asking is, if you took the planets and placed them on a flat surface setup exactly as they would appear in space, ie sun in the middle, each planet placed where it currently is in orbit in relation to each other, would some be floating above the table while some are underneath it?

Yes. At this scale even a slight difference in inclination translates to huge distances to the plane.

Or would you have them all sitting close enough to the same height as each other that this razor thin wave of energy moving across the surface would fly in a straight line and connect with them all? Maybe a different visualization. Here you stand, Fyraltari, destroyer of galaxies. You have found a solar system you want to destroy. Standing behind neptune and looking at the sun, your magical miracle vision allows you to see all the planets in the solar system at once. Are all the planets level with your vision? Is it a straight shot to hit them all at once? Or does the attack need to be more of a cube than a sheet of paper to connect with everything?

The attack would be a circular razor thin edge as wide as the solar system perpendicular to the line between me and the sun. That way it will cross every point in the sphere centered on the sun with the same radius as the solar system, meaning that even if a planet had an inclination of 90° to the ecliptic plane and was "currently" the furthest it can be from it, it would still be inside the blast radius.

Moving a bidimensionnal figure allows you to cover the third dimsension as well.

Think of medical scanner pictures, you see successive two-dimensionnal images that taken together represent the entirety of your three-dimensionnal body, that's the same concept.

[Lord Torath]

What im kinda asking is, if you took the planets and placed them on a flat surface setup exactly as they would appear in space, ie sun in the middle, each planet placed where it currently is in orbit in relation to each other, would some be floating above the table while some are underneath it? Or would you have them all sitting close enough to the same height as each other that this razor thin wave of energy moving across the surface would fly in a straight line and connect with them all? Maybe a different visualization. Here you stand, Fyraltari, destroyer of galaxies. You have found a solar system you want to destroy. Standing behind neptune and looking at the sun, your magical miracle vision allows you to see all the planets in the solar system at once. Are all the planets level with your vision? Is it a straight shot to hit them all at once? Or does the attack need to be more of a cube than a sheet of paper to connect with everything?

As has been said, none of the planets orbit in quite the same plane. The earth's orbit is 7 degrees off the the sun's equatorial plane.

Here's a list of the planets (and Pluto) and their orbital inclinations: Table.
Here's a table of the planets (and Pluto) with their average orbital distances: Table.

Multiply each planet's average orbital distance by the sine of its inclination to get the maximum distance the planet will ever be above or below.

Looks like, if you're coming in along the ecliptic, your worst culprit is Neptune, which can be up to 86.3 million miles away from the ecliptic. Next worst is Saturn, which can be 38.5 million from the ecliptic.

If you knew which side of the ecliptic each planet was, then a beam 124.8 million miles thick would catch all the current planets. If you didn't know which side of the ecliptic the planets were on, then you'd want to double Neptune's offset just to be safe: 172.6 million miles thick. If you want to center your beam on the sun, aligned with Earth's orbit (the ecliptic) your beam would need to be 5.6 billion miles wide and 172.6 million miles thick. Or in non-dumb units, that's 9.00 billion km wide and 278 million km thick.

That's an aspect ratio of about 32:1