How frequently are other planets in the Solar system hit by meteorites? For example, is the rate per unit area about the same?
1$\begingroup$ Note that there is a size distribution of bodies out there, that translates into a frequency distribution of impactors. Smaller sizes will hit more often. You might want to adjust your question with this regard. $\endgroup$– AtmosphericPrisonEscapeMar 2, 2020 at 2:32
1$\begingroup$ Can you please make this question clearer and more focused? From the title, it appears that you're asking about this solar system, but then in the question body you mention other star systems. Also, I really don't understand what your last sentence means. BTW, bodies in the solar system get hit by tiny meteorites all the time, so you may wish to specify a minimum size of the impactors that you're interested in. $\endgroup$– PM 2RingMar 2, 2020 at 3:12
1$\begingroup$ I've made an edit again here but in the future I'll start voting to close as unclear. Questions need to be well focused and ask for specific answers. I think bringing the Trappist system into your question makes it impossible to answer. Next time please first envision what an answer might be like before posting a question. $\endgroup$– uhohMar 2, 2020 at 3:42
Even though the Moon obviously isn't a planet, it's a good place to start as most of the observations of meteorites hitting other bodies has been focussed on the Moon. NASA runs the Meteoroid Environment Office which in part monitors lunar impacts. They state;
The lunar impact rate is very uncertain because observations for objects in this mass range are embarrassingly few. Source
This statement from what I can tell hold true for most objects in the solar system aside from the Earth. However according to this source reckons the moon receives around 2800kg of meteor material each day, which seems about right. The LRO and increased amounts of astronomical observations have led to this increased knowledge on the issue.
Aside from the Moon, Jupiter is probably the second most studied object in regards to meteorites. This is because it regularly has some fairly energetic collisions due to its large gravitational pull. According to this paper Jupiter can receive around 12-60 meteorites with comparable strength to the Chelyabinsk airburst each year.
Also noteworthy was the Shoemaker-Levy impact in 1994, which gave a lot of importance to the study of collisions and NEO studies.
Comet Shoemaker-Levy 9 Impact Source
Noteworthy planet as its only planet where we've found a meteorite on the surface and studied it up close. Opportunity, Spirit and Curiosity all found candidates for meteorites. Curiosity studied up close the iron meteorites Lebanon A and B.
On average, 33 metric tons (73,000 lbs) of meteoroids hit Earth every day. Source
Now while meteoroids don't count as meteorites, but this is useful in gaining a sense of the relative scale. The atmosphere of the Earth means that the meteoroids don't reach the surface, which separates Earth from objects without an atmosphere. Most atmosphere-less objects in the solar system have a fossil record of the amount of collisions they have received, in the form of all the craters on the surface.
There's still a lot of unknown information in the area, but observations are beginning to ramp up and with that we can began to gain an idea of just how frequently objects in the solar system are hit by meteorites, so in the future a number could be put forth for each planet in the solar system.
1$\begingroup$ Thank you for this informative answer. I have a question concerning your writing " the moon receives around 2800kg of meteor material each day, which seems about right" based on which intuition do you judge this as 'about right'? I am asking because I have no feeling for what I would expect. Did you integrate a scaled version of the asteroidal mass distribution function and multiply it with a gravitational cross section to get impact frequency and mass estimates? How do you 'feel' the number is not actually 100 times higher or lower? $\endgroup$ Mar 2, 2020 at 15:41
1$\begingroup$ @AtmosphericPrisonEscape I'm basing this assumption on the fact that the Earth receives around 33000kg per day, so the Moon receiving 2800kg seems to be in the right ballpark. I'm looking for a source for it, but for now I leave it as is, because it still is slightly doubtful. $\endgroup$ Mar 2, 2020 at 20:08
1$\begingroup$ Statistical analysis of the flux of micrometeoroids at Mercury from both cometary and asteroidal components "From our numerical simulations, we compute the fraction of particles hitting Earth and Mercury’s surface and the corresponding distribution of impact velocities." $\endgroup$ Mar 3, 2020 at 18:24