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[MonkeyHead]

Tried using that in my teaching before. Didnt work so well, basically older teenagers and young adults basically go straight for a moon sized lump of iron heading perpendicularly to the surface at a relatavisitic velocity, with fairly predictable outcomes.

Interestingly, you have a higher overall chance of dying from an asteroid impact than from a terrorist attack.

Fascinating! Any chance of a source or some maths to back that up before I start passing it off as fact?

[10ebbor10]

Since calculating stuff is fun.( And yes: I used the NASa database to get such things as impact velocity and angle).

That's what would happen if it fell in the middle of the ocean. (10km distance, iron rock 11m/s, stuff like that)

Spoiler (click to show/hide)

The crater opened in the water has a diameter of 2.36 km ( = 1.46 miles ).
For the crater formed in the seafloor:
The result of the impact is a crater field, not a single crater. The following dimensions are for the crater produced by the largest fragment.
Transient Crater Diameter: 3.75 cm ( = 1.48 inches )
Transient Crater Depth: 1.33 cm ( = 0.523 inches )
Final Crater Diameter: 4.69 cm ( = 1.85 inches )
Final Crater Depth: 9.99 mm ( = 3.94 tenths of an inch )
The crater formed is a simple crater.
The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 4.63 mm ( = 1.82 tenths of an inch ).
At this impact velocity ( < 12 km/s), little shock melting of the target occurs.


The Richter Scale Magnitude for this impact is less than zero; no seismic shaking will be felt.
The major seismic shaking will arrive approximately 2 seconds after impact.
Richter Scale Magnitude:  -7.7
Mercalli Scale Intensity at a distance of 10 km:

Nothing would be felt.  However, seismic equipment may still detect shaking.


The air blast will arrive approximately 30.3 seconds after impact.
Peak Overpressure: 34600 Pa = 0.346 bars = 4.91 psi
Max wind velocity: 71.5 m/s = 160 mph
Sound Intensity: 91 dB (May cause ear pain)

Damage Description:
Wood frame buildings will almost completely collapse.
Glass windows will shatter.
Up to 90 percent of trees blown down; remainder stripped of branches and leaves.


The impact-generated tsunami wave arrives approximately 1.94 minutes after impact.
Tsunami wave amplitude is between: 10.3 meters ( = 33.9 feet) and 38.9 meters ( = 128 feet).

If the asteroid isn't made from iron( Which it probably isn't) it'll just explode in the atmosphere.

Spoiler (click to show/hide)

The projectile begins to breakup at an altitude of 65500 meters = 215000 ft
The projectile bursts into a cloud of fragments at an altitude of 5860 meters = 19200 ft.
The residual velocity of the projectile fragments after the burst is 2.09 km/s = 1.3 miles/s.
The energy of the airburst is 9.89 x 10^15 Joules = 2.36 x 10^0 MegaTons.
No crater is formed, although large fragments may strike the surface.


Energy before atmospheric entry: 1.03 x 10^16 Joules = 2.45 MegaTons TNT

The average interval between impacts of this size somewhere on Earth is 761.3 years

The air blast will arrive approximately 35.1 seconds after impact.
Peak Overpressure: 21500 Pa = 0.215 bars = 3.05 psi
Max wind velocity: 46.5 m/s = 104 mph
Sound Intensity: 87 dB (Loud as heavy traffic)

Damage Description:
Glass windows will shatter.
About 30 percent of trees blown down; remainder have some branches and leaves blown off.

[Putnam]

It's probably a silicate asteroid, which would make it the latter.

Also, that does seem very tunguska like, the way it doesn't leave a crater yet explodes with 46.5 m/s winds.

[RedKing]

Heh...kinda fun trying to tweak the values to see just how much damage you can do without completely obliterating Earth. This one was pretty impressive:

Spoiler (click to show/hide)

Diamter: That of London (44.75km)
Density: Iron (8000/km^3)
Angle: 90 degrees
Velocity: 50 km/s
Target: Crystalline Rock
Distance from imact: 500km

Energy before atmospheric entry: 4.69 x 10^26 Joules = 1.12 x 10^11 MegaTons TNT

The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Transient Crater Diameter: 497 km ( = 309 miles )
Transient Crater Depth: 176 km ( = 109 miles )
Final Crater Diameter: 1120 km ( = 696 miles )
Final Crater Depth: 2.45 km ( = 1.52 miles )
The crater formed is a complex crater.
The volume of the target melted or vaporized is 4180000 km^3 ( = 1000000 miles^3 )
Roughly half the melt remains in the crater, where its average thickness is 21.5 km ( = 13.4 miles ).

Your position is in the region which collapses into the final crater.
The ejecta will arrive approximately 5.57 minutes after the impact.
Your position is beneath the continuous ejecta deposit.
Average Ejecta Thickness: 4.37 km ( = 2.71 miles )
Mean Fragment Diameter: 11.5 cm ( = 4.51 inches )

Time for maximum radiation: 31.1 seconds after impact
Your position is inside the fireball.
The fireball appears 697 times larger than the sun
Thermal Exposure: 8.82 x 10^11 Joules/m^2
Duration of Irradiation: 5.61 hours
Radiant flux (relative to the sun): 43700


Effects of Thermal Radiation: 
Clothing ignites.
Much of the body suffers third degree burns.
Newspaper ignites.
Plywood flames.
Deciduous trees ignite.
Grass ignites.

The major seismic shaking will arrive approximately 1.67 minutes after impact.
Richter Scale Magnitude:  12 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 500 km:

Most masonry and frame structures destroyed with their foundations.  Some well-built wooden structures and bridges destroyed.  Serious damage to dams, dikes, embankments.  Large landslides.  Water thrown on banks of canals, rivers, lakes, etc.  Sand and mud shifted horizontally on beaches and flat land.  Rails bent slightly.

As X.  Rails bent greatly.  Underground pipelines completely out of service.

The air blast will arrive approximately 25.3 minutes after impact.
Peak Overpressure: 120000000 Pa = 1200 bars = 17000 psi
Max wind velocity: 8820 m/s = 19700 mph
Sound Intensity: 162 dB (Dangerously Loud)

Damage Description:
Multistory wall-bearing buildings will collapse.
Wood frame buildings will almost completely collapse.
Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.
Highway truss bridges will collapse.
Highway girder bridges will collapse.
Glass windows will shatter.
Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.
Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

That's at 500km distance.  And yet, the Earth is more or less unperturbed in orbit and rotation.

[MonkeyHead]

Yea, the mass and various velocties of the Earth produce quite a hefty set momentums, both linear and angular. Would take a LOT to change any of them by anything noticable.

[Loud Whispers]

probably land in the ocean

Ohgod

This is the worst possible place for an asteroid to land in.

THE WORST

Any particular reason we can't shoot a remote detonated nuke at it?

Blow up the asteroid, you now have hundreds of thousands of smaller asteroids all on the same collision path :/

However simply moving the asteroid path would be much easier

Yea, the mass and various velocties of the Earth produce quite a hefty set momentums, both linear and angular. Would take a LOT to change any of them by anything noticable.

There have been Earthquakes which have done more

[MonkeyHead]

And even then, said earthquakes change litte about the Earths orbital dynamics.

[10ebbor10]

That's at 500km distance.  And yet, the Earth is more or less unperturbed in orbit and rotation.

Try something else then a 90 degrees impact angle.

probably land in the ocean

Ohgod

This is the worst possible place for an asteroid to land in.

THE WORST

It won't be that bad. Assuming it's made of iron and lands in the deepest part of the ocean, the waves would be barely noticable further then 100 km.

[Ultimuh]

For some strange reason.. I have a sudden urge to play Dino Run again. 

[Blargityblarg]

It's great fun setting the asteroid simulator to one degree angle of impact with a nonsensically big asteroid at 72m/s.

'Depending on the direction and location of the collision, the impact may cause a change in the length of the day of up to 2800 hours'

[Urist Imiknorris]

The chances that it'll actually hit us are apparently at 0.022%

Can I get a source for this?

[Loud Whispers]

probably land in the ocean

Ohgod

This is the worst possible place for an asteroid to land in.

THE WORST

It won't be that bad. Assuming it's made of iron and lands in the deepest part of the ocean, the waves would be barely noticable further then 100 km.

Ohgod

This is the WORST POSSIBLE THING to happen with the WORST POSSIBLE SCENARIO D:

[Guardian G.I.]

It's great fun setting the asteroid simulator to one degree angle of impact with a nonsensically big asteroid at 72m/s.

'Depending on the direction and location of the collision, the impact may cause a change in the length of the day of up to 2800 hours'

The Earth is not strongly disturbed by the impact and loses negligible mass.
65.61 percent of the Earth is melted.

[Loud Whispers]

65.61 percent of the Earth is melted.

Meanwhile in Australia

[Guardian G.I.]

65.61 percent of the Earth is melted.

Meanwhile in Australia

"Your position is inside the fireball.
The fireball appears 11800 times larger than the sun.
Duration of Irradiation: 1200 hours"