Of all the animals of prey, man is the only sociable one.
Every one of us preys upon his neighbour, and yet we herd together.
The Beggar's Opera: John Gay

Wednesday 11 December 2013

Contains moderate peril

We don't tend to get excited about asteroids unless they pass within the Moon's orbit but, in the case of 2013 XY8, we're prepared to make an exception.

2013 XY8 will be zipping past a mere 750,000-odd km away later today - or two lunar distances -  but, according to NASA's Near Earth Object Program, after a few more passes, the 40m wide asteroid has a 1-in-1,120 chance of an Earth impact on the 12th of December 2095.

This gives NASA & Co plenty of time to investigate ways to deflect it should the odds shorten further, though it is, in a way, disappointing that current reports suggest the favoured option will not be painting it white to increase solar deflection.

Unless someone comes up with an equally elegant and ingenious solution, we're back to Bruce Willis and the nukes.

All this talk of asteroid deflection may, of course, be rendered entirely academic if things start hotting up at Yellowstone's volcano. New measurements released this week show that it's about 2.5 times bigger than early estimates suggested:
The team found that the magma chamber was colossal, reaching depths of between 2km and 15km, the cavern was about 90km long and 30km wide.
The BBC report includes a spectacular simulated satellite view of a massive ash cloud emanating from the area, then spoils the effect by adding a caption which helpfully states the bleeding obvious:
It is unclear when the Yellowstone supervolcano will erupt again
Since all the calculations are based on three known eruptions, and the margin for error is in the order of millennia, the chances of anything kicking off in the lifetime of this blog are remote - though I promise I'll post on it the minute I hear of something happening there.

It's a reminder that, in the geological scheme of things, we are about as important as bacteria on the surface of a football; if enough of us act together we can cause some unsightly blemishes and bad smells but the football, by and large, ignores us.

I have a great respect for geologists, who somehow navigate the existential perils of what is essentially Douglas Adams' Total Perspective Vortex:
The prospective victim of the TPV is placed within a small chamber wherein is displayed a model of the entire universe - together with a microscopic dot bearing the legend "you are here". The sense of perspective thereby conveyed destroys the victim's mind.
Here in the Tavern, we  prefer to retreat to the immediate certainties of a brimming tankard and a worthy toast.

Ladies and gentlemen, let us drink to 2013 XY8 - many happy returns!


  1. I am with you entirely that we should be more concerned about asteroid impact. This is something we can do something about, given enough time, thought and investment.

    This latest report, however, raises an interesting question. The NASA NEO Programme website reports it will have a total impact energy of around 2.3 megatons (Mt, TNT equivalent, so approx 9.7x10^15 Joules). In the grand scale of things, this is not a lot; it's about 150 to 200 times the energy in each of the Hiroshima and Nagasaki atomic bombs (which were carefully targetted to have maximum effect and released all their energy near instantaneously over the selected target(s)). It is about one tenth of the 'surface rupture energy' of the 2004 Indian Ocean earthquake.

    Other interesting comparisons include: (i) The Tunguska event: asteroid or comet impact in Russia in 1908, with estimated energy of 10 to 15Mt; (ii) The Chelyabinsk meteor: air burst over Russia in February 2013, with an estimated energy of 0.5Mt.

    So the interesting question is: what is the asteroid energy threshold at which it is worth deflecting it, as distinct from other protective measures such as evacuation (assuming one has time after predicting the likely arc of 'impact'), or investing the one-off cost (as distinct from the development cost that is shareable) in something else likely to offer better cost-benefit.

    There is an opinion on this, stated as from NASA, recorded in Wikipedia, which puts the 'dangerous' diameter as in excess of 100m to 150m. So 2013 XY8 does not make that threat level. However, it would likely be devastating over a modest area.

    Also interesting is how to measure the mass (which unfortunately drops out of the orbit calculations). Albedo (primarily sunlight reflection) is the usual method, but this is very approximate.

    Detection in advance also is problematic, with several modest sized impacts every year with no or negligible advanced notice. I wonder what is the current political cost-benefit analysis that is holding back further investment: eg chasing, 'catching up with' and observing an asteroid on near Earth fly-by? This seems to me to be an obvious step in almost all deflection strategies.

    Best regards

  2. NS, my thanks for yet another comment considerably more detailed and interesting than the original post.

    The question of threshold effectively adds up to a massive game of 'chicken', I suppose; the longer we wait, the more we know about the threat but the less time we have to tackle it.

    It does raise the question, though of whether we have - or will have 80 years hence - the ability to perform a minor deflection and steer small meteorites into uninhabited areas of the globe, and whether that would be more cost-effective than deep-space intervention.

  3. "I promise I'll post on it the minute I hear of something happening there."

    You won't have to, we'll all be dead.

  4. R, as long as these chaps are on the ball, there should be some indication in advance:


    though, slightly worryingly, their Yelowstone page is only updated once a week and, if the BBC drama-documentary* is anything to go by, their field geologists will be the first to go (while making impossibly heroic attempts to escape).

    *There's even a play-along version

    ...and, in any case, I'm sure Demetrius is keeping an eye open on our behalf.

  5. We are all doomed, eventually.

  6. 2013 XY8 will be zipping past a mere 750,000-odd km away later today - or two lunar distances

    Damn - missed it!


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