Would a nuclear blast on an exoplanet be detectable from Earth?

[2552]

Say there is a planet, about 20 to 50 light-years away, with an intelligent civilization on it, with nuclear technology, and a nuclear bomb was detonated on the Earth-facing side of the planet. Would the explosion be bright enough to be seen by the Hubble Space Telescope, if it happened to be pointing in the right direction at the right time? Would we know from it's spectra that it was probably a nuke and not a GRB or something?

Another thought, could a spacecraft powered by Nuclear pulse propulsion also be detected?

[toromos]

It's only been very recent that we've had visual detection of an exoplanet, and it appears as a tiny blip of light. I don't think any source of light on the planet could be detected by us unless it could somehow outshine the light that it reflects from its star.

[iquestor]

Say there is a planet, about 20 to 50 light-years away, with an intelligent civilization on it, with nuclear technology, and a nuclear bomb was detonated on the Earth-facing side of the planet. Would the explosion be bright enough to be seen by the Hubble Space Telescope, if it happened to be pointing in the right direction at the right time? Would we know from it's spectra that it was probably a nuke and not a GRB or something?

Another thought, could a spacecraft powered by Nuclear pulse propulsion also be detected?

Problem 1 is that the planet itself wouldnt be directly detectable at all from Earth or Hubble; the Kepler mission uses the transit method to detect planets, but its not a direct LOS kind of thing. A nuclear explosion that didnt blow up the whole planet would likely not be detectable unless the amount of radiation exceeded the relative brightness of that local star, as seen from Earth.

I dont know if a nuke explosion would release radiation that would be different enough from that which emitted from the local star as to provide contrast to normal backgroud, but if it did, and we were looking for that explicitly, then perhaps, IF we had direct Line Of Site AND we were looking for something that would stand out from normal background radiation. Certainly not anything in the visible spectrum; the local star would drowned that out.

Problem 2 is Line of Sight. This depends on the relative positions of both solar systems. There is the relative angle between the ecliptic planes of both systems, as well as the relationship of each planet's orbital period to the other, as well as the time it takes for 1 revolution. these variables will determine the fraction of an Earth Year which there would be any possible LOS between Earth and the other planet. This could be anywhere from 0% to approaching 45%, IF the planets each had a very similar orbital period and were 180 degrees out of phase with each other, i.e. the perhelion points of the orbit of each planet happened on the same cycles and were on adjacent sides of the local stars. And the stars would also have to have similar masses and in the same part of their main sequences. I dont think it could ever be even 50% because in the beginning and end of the cycles each planet's view of the other would be diminished due to the local's stars radiation.

I am assuming of course that the exoplanet is in the habitable zone, so that rules out a very fast or very slow orbital period.

I am sure there are lots of other variables... it would seem to be a situation where you were looking for something extremely specific at exactly the right time and place, and there would have to be a lot of circumstantial occurances to make it beleivable.

I assume you are writing a story? or just had an interesting thought?

[2552]

I just had the idea a few days ago, thanks for the answers.

[01101001]

I just had the idea a few days ago, thanks for the answers.

Welcome to BAUT Forum.

Cool name. Needs more 0s and 1s though.

[Romanus]

Sorry to say that any explosion powerful enough to see from 20 light-years away with current technology would be enough to obliterate said planet.

However, all is not lost; the Strategic Defense Initiative ("Star Wars") program supposedly did some work with nuke-sparked X-ray lasers. If your putative civilization used such a beam--souped-up, of course--and placed it well away from its planet, it would generate a narrow, temporary beam that might nonetheless be powerful enough to be both easily detected and decidedly artificial. Hubble couldn't see it, of course, but Chandra, Swift, or any next-generation successors might be able to.

If you are writing a story with it, I wish you luck.

[Murphy]

I'm not exactly sure of the answer to the question, but the basic principle seems similar to detecting a spaceship, which is detailed in this page http://www.projectrho.com/rocket/rocket3w.html, from Atomic Rockets.

BTW a Nuke would indeed produce light of a very different frequency to a normal star, Gamma rays would be the thing to look for.

[ravens_cry]

I remember one early hypotheses to explain gamma ray bursts was a nuclear war on an exoplanet. Rather a depressing thought to put it mildly.

[Ara Pacis]

Perhaps one day we'll have VLBI 'scopes in space to make resolution of such fine detail closer to possible. There might still be problems of glare from the parent star. another method might be to look for neutrino emissions from thermonukes, which are or a different form from stellar neutrinos, IIRC.

[MaDeR]

Why so elaborate?

Answer: no.

Just that. Simple.

[trinitree88]

Sorry to say that any explosion powerful enough to see from 20 light-years away with current technology would be enough to obliterate said planet.

However, all is not lost; the Strategic Defense Initiative ("Star Wars") program supposedly did some work with nuke-sparked X-ray lasers. If your putative civilization used such a beam--souped-up, of course--and placed it well away from its planet, it would generate a narrow, temporary beam that might nonetheless be powerful enough to be both easily detected and decidedly artificial. Hubble couldn't see it, of course, but Chandra, Swift, or any next-generation successors might be able to.

If you are writing a story with it, I wish you luck.

Romanus. SDI x-ray lasers, and subsequently grasers, were and are highly classified research. Most of the publications and authors were sequestered away from mainline journals.
MaDeR. It is not inconceivable to make much bigger H-bombs. The only prohibition is money. One could launch an enormous quantity of lithium deuteride into orbit. Then place a thermonuclear bomb inside, and light it up. It would make a very bright light compared to your standard missile warhead, and would have a trace of transuranic spectral lines.

[ravens_cry]

One could launch an enormous quantity of lithium deuteride into orbit. Then place a thermonuclear bomb inside, and light it up. It would make a very bright light compared to your standard missile warhead, and would have a trace of transuranic spectral lines.

As well as making an immense electromagnetic pulse, which would be a Bad Thing.

[Ara Pacis]

As well as making an immense electromagnetic pulse, which would be a Bad Thing.

Only on the local planet, if it has a magnetic field.

[Philippe Lemay]

I think that the best candidate for being spotted would be the nuclear-pulse propulsion one. In an atmosphere a lot of the nuke's main "flash" is absorbed by the ambient atmosphere, so that only a fraction of the gamma rays would reach outer space.

If the bomb is already in outer space, the gammas can be seen much more directly. And they would probably be used in sequence, since the ship would need more than one charge to get where it wants to go. Plus, if this hypothetical ship is designed to leave it's system, it would gradually move away from it's parent star, reducing the problem of sun-glare.

With a sufficiently sensitive telescope on our part, I think we could see it. It would be damned unlikely, but possible.

[MaDeR]

MaDeR. It is not inconceivable to make much bigger H-bombs.

OP didn't asked about some made up uberbig H-bomb - at least he did not indicate it. It is safe to assume that he asked about normal nuclear weapon, such as our own existing stockpiles.

One could launch an enormous quantity of lithium deuteride into orbit. Then place a thermonuclear bomb inside, and light it up. It would make a very bright light compared to your standard missile warhead, and would have a trace of transuranic spectral lines.

This is not what he asked about at all. He did not asked how one could try to outshine star as seen from Hubble.

He asked just that:

Say there is a planet, about 20 to 50 light-years away, with an intelligent civilization on it, with nuclear technology, and a nuclear bomb was detonated on the Earth-facing side of the planet. Would the explosion be bright enough to be seen by the Hubble Space Telescope, if it happened to be pointing in the right direction at the right time?

In short, can nuclear detonation be visible to us? Answer is NO. Do you deny it?

[Ilya]

Say there is a planet, about 20 to 50 light-years away, with an intelligent civilization on it, with nuclear technology, and a nuclear bomb was detonated on the Earth-facing side of the planet. Would the explosion be bright enough to be seen by the Hubble Space Telescope, if it happened to be pointing in the right direction at the right time?

In visible light -- absolutely not.

In gamma rays -- not with anything we have currently, but it is not quite as absurd as in visible light, since you do not have to contend with planet's sun drowning out the flash. (Main sequence stars do not emit any gamma-rays to speak of.)

[trinitree88]

OP didn't asked about some made up uberbig H-bomb - at least he did not indicate it. It is safe to assume that he asked about normal nuclear weapon, such as our own existing stockpiles.


This is not what he asked about at all. He did not asked how one could try to outshine star as seen from Hubble.

He asked just that:

In short, can nuclear detonation be visible to us? Answer is NO. Do you deny it?

Under those conditions, nope. Yer right. Have a drink on me. pete