If 100 km size body will fall on the Sun it would produce the flash 1000 times stronger than the Sun’s luminosity for 1 second, which would result in fires and skin burns for humans on day side of Earth.
The calculation is just calculation of energy of impact, and many “ifs” are not accounted, which could weaken consequences or increase them. Such body could be from the family of Sun grazing comets which originate from Oort cloud. The risk is not widely recognized and it is just my idea.
The basis for this calculation is following: Comets hit the Sun with speed of 600 km/s, and mass of 100 km size body (the comets of this size do exist) is 10e18 kg, so the energy of impact is 3.6x10e29 J, while Sun’s luminosity is 3x10e26 W.
I found one paper about comets crashing into the sun, but unfortunately they don’t consider as big comets as you do—the largest one is a “Hale-Bopp sized” one, which they take to be 10^15 kg (which already seems a little low, Wikipedia suggests 10^16 kg.)
I guess the biggest uncertainty is how common so big comets are (so, how often should we expect to see one crash into the sun). In particular, I think the known sun-grazing comets are much smaller than the big comet you consider.
Also, I wonder a bit about your 1 second. The paper says,
The
primary response, which we consider here, will be fast
formation of a localized hot airburst as solar atmospheric gas
passes through the bow-shock. Energy from this airburst will
propagate outward as prompt electromagnetic radiation (unless
or until bottled up by a large increase in optical depth of the
surrounding atmosphere as it ionizes), then in a slower
secondary phase also involving thermal conduction and mass
motion as the expanding hot plume rises.
If a lot of the energy reaching the Earth comes from the prompt radiation, then it should arrive in one big pulse. On the other hand, if the comet plunges deep into the sun, and most of the energy is absorbed and then transmitted via thermal conduction and mass motion, then that must be a much slower process. By comparison, a solar flare involves between 10^20 and 10^25 J, and it takes several minutes to develop.
Most likely the energy will be released below sun’s photosphere, as its density is very low like 1 to 6000 of air. This would prevent immediate flash visibility. The resulting hot gas will flow up eventually but it will cooler and energy less concentrated. But even if it takes several minutes, it still could produce burns on Earth.
Also something like large Solar flash could happen because of integration of the hot gas from the comet with Sun’s magnetic field, and it hypothetically will result in superflare with strong Solar wind and magnetic effect on Earth.
The temperature during impact will be around 5 mln K on the edge of the comet, as I calculated, which is not enough for any meaningful nuclear reactions. But it doesn’t include any additional heating connected with rising pressure because—and pressure would rise as the comet will compress as it decelerate in the solar medium.
If such reaction will happen it could add more energy to explosion and also produce some radioactive isotopes, which could later become part of Solar find and fallout on Earth. I saw an article long time before about possibility of nuclear reaction during impacts, and I will find it.
Comet will not deform as it will be completely vaporised.
After impact of Shumeicker-Levi comet with Jupiter large waves in its atmosphere were observed. So some part of the energy will definitely go into mechanical pressure changes. But I don’t think that most part as a cloud of gas after impact will be extremely hot and will radiate very strong.
I suspect that the higher is speed of the impact, the bigger part of it will go into radiation.
And as the Sun photospere is saturated with radiation energy, it will radiate any excessive energy.
Vaporising a comet takes significant energy. Heating up a comet to vaporization point takes significant energy. Dissipating the vaporized comet (still the same total mass and momentum as when it was in a solid state) takes significant energy. I really find this simplistic a treatment to be not useful. Still an interesting thought-experiment and a little scary.
It has enormous energy at its free fall speed of 600 km at sec. It is 10-20 times quicker than speed of meteor collision with earth and so provide 100 or more time energy for any kg of impacting material.
Вut the main problem for “big bang” here is that atmosphere of the Sun is very thin on its photosphere level, so most of the comet will go intact under it (if it will not break into many smaller pieces before impact which is possible because of string tidal forces, evaporation etc—in with case the flash will be much more visible.)
Any insights about the following calculation?
If 100 km size body will fall on the Sun it would produce the flash 1000 times stronger than the Sun’s luminosity for 1 second, which would result in fires and skin burns for humans on day side of Earth.
The calculation is just calculation of energy of impact, and many “ifs” are not accounted, which could weaken consequences or increase them. Such body could be from the family of Sun grazing comets which originate from Oort cloud. The risk is not widely recognized and it is just my idea.
The basis for this calculation is following: Comets hit the Sun with speed of 600 km/s, and mass of 100 km size body (the comets of this size do exist) is 10e18 kg, so the energy of impact is 3.6x10e29 J, while Sun’s luminosity is 3x10e26 W.
It sounds pretty spectactular!
I found one paper about comets crashing into the sun, but unfortunately they don’t consider as big comets as you do—the largest one is a “Hale-Bopp sized” one, which they take to be 10^15 kg (which already seems a little low, Wikipedia suggests 10^16 kg.)
I guess the biggest uncertainty is how common so big comets are (so, how often should we expect to see one crash into the sun). In particular, I think the known sun-grazing comets are much smaller than the big comet you consider.
Also, I wonder a bit about your 1 second. The paper says,
If a lot of the energy reaching the Earth comes from the prompt radiation, then it should arrive in one big pulse. On the other hand, if the comet plunges deep into the sun, and most of the energy is absorbed and then transmitted via thermal conduction and mass motion, then that must be a much slower process. By comparison, a solar flare involves between 10^20 and 10^25 J, and it takes several minutes to develop.
I thought more after I posted and concluded that:
Most likely the energy will be released below sun’s photosphere, as its density is very low like 1 to 6000 of air. This would prevent immediate flash visibility.
The resulting hot gas will flow up eventually but it will cooler and energy less concentrated. But even if it takes several minutes, it still could produce burns on Earth.
Also something like large Solar flash could happen because of integration of the hot gas from the comet with Sun’s magnetic field, and it hypothetically will result in superflare with strong Solar wind and magnetic effect on Earth.
The temperature during impact will be around 5 mln K on the edge of the comet, as I calculated, which is not enough for any meaningful nuclear reactions. But it doesn’t include any additional heating connected with rising pressure because—and pressure would rise as the comet will compress as it decelerate in the solar medium.
If such reaction will happen it could add more energy to explosion and also produce some radioactive isotopes, which could later become part of Solar find and fallout on Earth. I saw an article long time before about possibility of nuclear reaction during impacts, and I will find it.
Wouldn’t most of the energy go into mechanical deformation of the comet and the sun, rather than EM radiation?
Comet will not deform as it will be completely vaporised.
After impact of Shumeicker-Levi comet with Jupiter large waves in its atmosphere were observed. So some part of the energy will definitely go into mechanical pressure changes. But I don’t think that most part as a cloud of gas after impact will be extremely hot and will radiate very strong.
I suspect that the higher is speed of the impact, the bigger part of it will go into radiation.
And as the Sun photospere is saturated with radiation energy, it will radiate any excessive energy.
Vaporising a comet takes significant energy. Heating up a comet to vaporization point takes significant energy. Dissipating the vaporized comet (still the same total mass and momentum as when it was in a solid state) takes significant energy. I really find this simplistic a treatment to be not useful. Still an interesting thought-experiment and a little scary.
It has enormous energy at its free fall speed of 600 km at sec. It is 10-20 times quicker than speed of meteor collision with earth and so provide 100 or more time energy for any kg of impacting material.
Вut the main problem for “big bang” here is that atmosphere of the Sun is very thin on its photosphere level, so most of the comet will go intact under it (if it will not break into many smaller pieces before impact which is possible because of string tidal forces, evaporation etc—in with case the flash will be much more visible.)