Okay, question for astronomers, physicists, and/or nuclear weapon enthusiasts:
If there was a nuclear detonation on the surface of Mars*, would you be able to see it with an Earth-based telescope?
If so, how big a nuke, and how large of a telescope? And what parts of Mars, and when, would a nuke going off be the most visible?
Presumably, speaking largely from ignorance, a larger telescope could see a smaller nuke, and vice versa. But I don’t even know if a 100 Megaton whopper would even be a noticable twinkle.
So…anyone want to weigh in?
*Not the side facing completely away from Earth at the time, presumably.
Also the Shoemaker-Levy 9 collision released enormously more energy than any nuclear weapon. The impact of the largest (G) fragment released the equivalent of 6 million megatons of TNT. Of course Jupiter is a lot farther from Earth than Mars ever is.
Galileo saw Shoemaker-Levy 9 while it was on the way to Jupiter. images. Distance was 238 million km, which is about 1.6 AU. Mars is often is closer than that to Earth. Galileo only had a 25 cm telescope, which is very small compared to professional and many amateur scopes. On the other hand, Galileo didn’t have to worry about being in Earth’s atmosphere.
Another factor is that a nuke on Mars will have a much bigger mushroom cloud, because there’s lots less atmosphere to contain it. A surface blast will send stuff into space, possibly even to escape velocity (which is much lower on Mars than Earth).
My guess: If Mars is near opposition, it could easily be seen, even with fairly small scopes. At other times, maybe the Hubble Space Telescope could see it, provided Mars isn’t on the far side of the Sun. However, no matter when it’s seen, it might not be distinguishable from a dust storm, which are a common happening on Mars. The size of the blast probably wouldn’t make much difference in its visibility.
The flash of light (the part most likely to be visible over astronomic distances) lasts a bit less than a millisecond. (Possible to design for duration of radiative effects, but two milliseconds is waaaay out of reach.) The percentage of milliseconds during which most objects in our solar system are under direct telescopic observation is significantly smaller than you might imagine, and there are 86 million milliseconds in a day. Most of the most powerful telescopes are not watching planets. The entire planet Mars appears as a dot of light without a telescope, and a historically sized nuclear blast would not be a significant increase in the total light emitted. A device exploded in a vacant part of the sky would be more likely to be noticed, but probably not it’s visible light. Empty sky is surveyed for gamma radiation and x-ray radiation far more than visual spectra. Still a long shot, though. Too many milliseconds, too much sky. To most human observers a nuke outside the orbit of Mars isn’t a “What the hell was that?” sort of event.
As a planned observation, it’s not at all unlikely, but it’s mostly an anomaly in a digital print out. Most astronomers don’t actually get to “look” through their professional equipment. Pretty much all of them would get out their home equipment, though, if you gave them advanced notice.
The gamma-ray detectors on the Fermi Gamma-Ray Space Telescope cover about 20% of the sky at a time. Detection is still not anywhere near guaranteed, but the shot might not be as long as you think.
Depends on what size telescope is needed, and on where Mars is relative to Earth. When they are in conjunction, nobody on Earth will be looking at Mars. When they are in opposition, I would guess someone is looking at Mars at all times through amateur telescopes.
Just want to make it clear that I was talking about the mushroom cloud in the above paragraph, not the gamma ray flash. The mushroom cloud will likely persist and become a dust storm.
As said above, gamma/X-ray satellites may see the flash, but they have notoriously bad resolution. In other words, they may see it, but won’t be able to say for certain that it happened on Mars, just in that general direction. And since such bursts normally don’t occur on Mars, the scientists are likely to think it happened much further away, as in bllions of light years and that it was just an coincidence that Mars was in that direction at the time. Other astronomers may train optical and radio telescopes at the position of the flash to see if they can find what caused it, but they probably won’t pay any attention to what’s happening on Mars.
However, some amateur astronomers look at Mars a lot and they would notice a sudden new dust storm if the planet were reasonably close to opposition. Perhaps some conspiracy theorist among them would connect the GRB with the new dust storm and come up with the hypothesis that a nuke had gone off on Mars. He would, of course, be either ignored or ridiculed by his fellow observers.
I wonder if this is actually the case. The fireball and mushroom cloud of an atomic explosion are atmospheric effects, and with Mars being much closer to a vacuum, would that not make the explosion less noticeable?
FWIW, according to Wikipedia, “Optical ground-based telescopes are typically limited to resolving features [on Mars] about 300 kilometers (190 mi) across when Earth and Mars are closest because of Earth’s atmosphere.” That would be a pretty damn big mushroom cloud. I’m not an expert but I don’t see why the mushroom cloud would persist and turn into a global dust storm.
Probably impossible to say without modeling. My guess is that a nuke would throw so much dust into the air that it would look (from the distance of the Earth) much like a dust storm. It may never look like a classic mushroom cloud, though, because of the great difference in atmospheric pressure. BTW, I’m thinking of a ground burst here; an air burst may not throw as much dust into the air.
As far as a visible light flash/fireball, there isn’t as much air to be heated up, but that just means more of the radiation will heat up the ground/dust and that should get hot enough to radiate in the visible band. Whether that’s visible from Earth will probably depend on the yield of the explosion. But if it is, many amateurs take video of their observing sessions. For instance, there’s been a handful of meteors in Jupiter’s atmosphere that have been caught this way. So the fireball may be captured that way.
ISTM the question boils down to how many lumens would a nuclear explosion create then
Would that light be visible by our largest telescopes?
Would it be sufficiently large enough to be resolved by the telescopes?
assuming Mars’ closest approach to Earth of 56 million kilometers. This article implies that a nuclear explosion can be as bright as the Sun so that would be a yes would be a yes to #1 (the Sun is about 150 million Km from Earth)
But better yet, go to page 6 figure 7. It gives the magnitude of various kiloton yields at 1 AU (absolute magnitude). At Mar’s closest approach it would be about 2.758 brighter (inverse square law) which is a hair above 1 magnitude brighter so again we see that the brightness would be very easily seen.
Note that these are all for explosions in air so I’ll leave it to experts to say if it would or would not be brighter in Mars’ atmosphere. Read the last page. The author points out some real-life issues beyond the theoretical and discusses whether we can see a nuclear explosion detonated by the AlphaCentaurs.
It occured to me that even if someone was looking at/videoing Mars at the time of the explosion and caught the flash, they would probably assume it was an asteroid strike rather than a nuke. Unless they had some reason to think otherwise, of course. Without special equipment such as a spectroscope, the two look pretty much alike from the distances involved.
A nuclear detonation as bright as the Sun? I doubt that.
The energy that would be released by all the nuclear weapons in the world is 2.5 x 10^16 J.
The energy that is released by the Sun every second is 3.86 x 10^26 J.
To be as bright as the Sun, however briefly, all the weapons in the would would need to emit their light within a single ten-billionth of a second. In practice the flash lasts a thousand times as long, so the light would only be 1/1000 times as bright as the Sun.
It depends on what you mean by “as bright as the Sun”. The total luminosity will, of course, be far lower. But it’s also much more concentrated, so the surface brightness probably is much greater.
You might get a better chance to see the flash if it happened a few tens of kilometers above the surface. This would illuminate a bigger area and spread out the length of the flash a bit as well.
Brightness is luminosity per unit area. For example the Sun is equally bright as seen from Mercury, the Moon and Pluto. This is known as the conservation of brightness.
