Space Rock Just Misses The Earth

[The Romulan Republic]

I am going to send the Obama Administration an email with a link to this story and a politely worded demand for a doubling of NASA's budget.

[Sky Captain]

Sometimes asteroids even smaller than this survive reentry, make it to the ground and produce a sizable blast. For example 110 m wide Kali crater in Estonia was estimated to be made by a meteorite massing 20 - 80 tons - that`s a rock only few meters in size. If a meteorite like this hits a densely populated area it could cause thousands of causalities.

http://en.wikipedia.org/wiki/Kaali_crater

[Darth Wong]

Leaving aside the inherent unreliability of Wikipedia, did it occur to you that the size at impact would have been considerably smaller than the size at time of atmospheric entry?

[Kanastrous]

Favorite photograph: the one labeled 'seen from front.'

It's circular.

What makes that the front?

[Forum Troll]

I think there's been too much focus on just whether the object reaches the ground or not. While for a sufficiently small, low-energy meteor, if such doesn't reach the ground and disperses its kinetic energy at high altitude, that means such is harmless, here we are talking not about sub-kiloton energies, nor just a few kilotons, but rather megaton level energies.

Consider history, the Tunguska event. An asteroid never reached the ground, yet, despite the lack of a classical impact crater, its blast leveled forests over literally a few hundred square miles of area, being effectively a 5 to 30 megaton airburst at 5 to 10 kilometers altitude.

This particular object apparently would have been lesser energy but still up to megaton-level.

Fortunately, casualties would likely have been low, even if it did hit earth. Most people vastly overestimate average population density due to living in cities or surrounding suburbs themselves, but urban areas cover only 3% of the world's total area. The asteroid would even have a 70% chance of just entering over the ocean, and it would be too small to cause a big tsunami.

Bigger asteroid impactors than this are the top concern.

[defanatic]

When they say a thousand atomic bombs, which sort of bomb are they talking about? Little Boys or Tsar Bombs, or something in between?

[starslayer]

When they say a thousand atomic bombs, which sort of bomb are they talking about? Little Boys or Tsar Bombs, or something in between?

Usually they mean something on the order of Little Boy/Hiroshima equivalent. They'll usually specify "hydrogen bomb" if they mean something of megaton size, IIRC.

[Sky Captain]

Leaving aside the inherent unreliability of Wikipedia, did it occur to you that the size at impact would have been considerably smaller than the size at time of atmospheric entry?

That`s for sure, before atmospheric entry Kali meteorite was possibly several times more massive.

http://muinas.struktuur.ee/projektid/ec ... facts.html

Kali crater homepage says it`s initial mass were estimated in a range between 400 to 10000 tons. Kali meteorite also was nickel-iron, it`s denser and stronger than mere rock so there are bigger chance it makes to the ground without exploding in high altitude.