How big would a meteor or meteorite have to be to cause major damage if it hit earht in a non-populated area?
Depends on what you mean by “major” damage. The last meteorite that caused major damage to a nonpopulated area occurred in 1908 in Siberia.
There were a couple of “near” misses earlier in the year and the size of the rocks were in the 50-100 yard range.
It was reported that if either had hit a populated area, a medium sized city could have been pretty much destroyed. I find such reports quite amazing, an object so relatively small could do that much damage.
It’s not the mass, it’s the velocity. The energy of an object is proprotional linearly to the mass (double the mass and you double the energy) but with the velocity squared (double the velocity and you get 4X the energy).
One meter sized boulder blow up very high in the atmosphere, yielding roughly kiloton-sized explosions roughly once per month, IIRC.
Bigger ones can hit the ground, or if they are made of nickle/iron and not rock. Past the 100 meter range, it doesn’t matter much what they are made of. Yikes.
Kinetic energy is equal to one half the mass of the object, times the square of its relative velocity. A fifty meter radius sphere of iron weighs 7874 k/m[sup]3[/sup] x 50 m[sup]3[/sup] x pi x 4/3 or 4,122,816,759 kg. While it might look small compared to Hollywood asteroids; we are taking about a very massive object. Of course an ice fragment would weigh much less, although only by a factor eight.
But the big values come in when you square the velocity of a meteor. Meteors have velocities which vary significantly, however they cannot generally be above 42 Kilometers per second, since that would be above the escape velocity of the solar system, in the region of Earth’s orbit, and such objects could not remain in the system.
Considering half that value as a reasonable maximum (a wild assed guess, of course) we have a value of 20,000 m/s, which makes our hypothetical chunk of iron now a kinetic energy input of 1.649 x 10 [sup]18[/sup] km[sup]2[/sup]/s[sup]2[/sup], or 1,649,000,000,000,000,000 Nm (newton meters). About 458,055 gigawatt/hours worth of energy released in a few seconds. That is the rough equivalent of two days energy use for the entire United States. (assuming I didn’t drop a decimal anywhere along the way)
Tris