How to Vapourise London

Hypothetically speaking, anyway…

According to this funky little impact calculator widget, this is the size of the impact crater that would form if an iron meteor with a 15km radius hit London head on at 60km/s. Even 500km away from the impact, clothing, paper, wood and even grass would ignite. Buildings and up to 90% of trees would be knocked down. Most of North West Europe would be a mess. Most of the UK would be completely destroyed. Fortunately, the probability of this happening is only once in nearly 4 billion years.

Good thing it’s all hypothetical! This calculator is pretty fun to play about with. You can set the size of the meteor (from 100m to 15km), the material it’s made from, the incident angle, the impact velocity… And then see how deep the hole is afterwards compared to certain famous landmarks like the Eiffel Tower.

Try looking up some stats on Wikipedia. I managed to recreate Halley’s Comet. The dreaded near-Earth asteroid Apophis is mercifully small actually, at only around 270m in radius. Enough to do some damage. Probably not large enough to destroy any entire countries (except possibly Liechtenstein), but still enough to shatter windows from 300km away. Makes you think…

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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4 Responses to How to Vapourise London

  1. invaderxan says:

    Oh definitely… That’s got to be the most interesting part about the theories. We just don’t know for sure! :)
    And thanks! Yeah, Betegeuse is about the closest Type II candidate to my knowledge, and it’s over 400ly from us.
    Type Ia candidates definitely are a lot harder to find, it’s true — you’re spot on with the reason why, too. I think the nearest known Type Ia candidate is IK Pegasi around 150ly away — though we probably have a few million years before that happens. :)

  2. stargzr_htn says:

    Yes, of course, on the statistics & on the other causes of extinction. There are still quite a few holes in the ground, though …
    I liked your supernova article. There aren’t any Type II progenitors closer that, say, Betelgeuse, right? Seems like the Type Ia progenitors would be harder to spot, though. There are a lot of binaries with white dwarfs out there, many with unknown masses, yes?

  3. invaderxan says:

    I don’t know, in truth — I’m just quoting the simulator…
    Though the Cretaceous extinction event makes one impact known (within reasonable doubt) to humanity over the past 4 billion years or so. Statistically, that seems consistent to me. Though I have no idea what factors they’ve used to calculate it in the simulator.
    Of course, a probability is simply that. It certainly doesn’t preclude a higher impact frequency… Lighning never striking twice and all of that. :)
    Other extinctions though, do have other theories regarding their causes.

  4. stargzr_htn says:

    That time frame can’t be right .. a bigger one than that happened at the KT boundary, only 65 million years ago. There other extinction periods as well, that may or may not be impact related. Or are you putting in a factor for actually hitting London, as opposed somewhere on Earth?

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