So I'm watching "Armageddon"...

[PlutonianEmpire]

And i was wondering, what exactly would happen if an object the size of texas were to actually hit the Earth?

[ajtribick]

Assuming "the size of Texas" refers to diameter, that's basically Ceres-size.

So: radius=500 km, density=3000 kg/m??

Mass = 1.6E+27 kg

Let's take an impact velocity of 11 km/s, and calculate the kinetic energy

KE = 9.7E+28 J

That's quite a lot. Let's see what this would do. Since the asteroid is rather small in comparison to the Earth, I'm going to take it's area as negligible.

The surface area of the Earth is 5.1E+14 m^2

Assuming that it has density 3000 kg/m??, and specific heat capacity 300 J/kg/K (based on the value for granite), and a melting point of 1300 K (to take a fairly arbitrary value), and an initial temperature of 500 K (another fairly arbitrary value).

So, how deep will this impact start to melt stuff? (This assumes no energy is required for the change of state, which is of course a ludicrous assumption, but then again, so are a few of the others I'm making)

The mass melted is 4.0E+23 kg, which corresponds to a depth of about 260 km.

Melting the planet to a depth of over 200 km is probably an extremely unpleasant experience for anything unfortunate enough to live there.

I've ignored a whole load of things like conservation of momentum, the fact that the heat capacity changes, changes of state, vapourisation, and some of my numbers for densities and heat capacities are probably wrong too, but I never claimed this is an accurate value.

[PlutonianEmpire]

And the worldwide effects would be what?

[ajtribick]

And the worldwide effects would be what?

Hmmm... I wonder what the worldwide effects of turning the planet into a global lava ocean 200 km deep would be?

Personally, I reckon the price of mango juice would skyrocket, the market for central heating would collapse overnight, and the president of the United States would be impeached.

Other than that, not much.

[PlutonianEmpire]

And the worldwide effects would be what?

Hmmm... I wonder what the worldwide effects of turning the planet into a global lava ocean 200 km deep would be?

Oh. sorry. I missunderstood.

[WildMoon]

And the worldwide effects would be what?

Hmmm... I wonder what the worldwide effects of turning the planet into a global lava ocean 200 km deep would be?

Personally, I reckon the price of mango juice would skyrocket, the market for central heating would collapse overnight, and the president of the United States would be impeached.

Other than that, not much.

[julesstoop]

http://www.lpl.arizona.edu/impacteffects/