Phil "Bad Astronomer" Plait explains the Russian meteor incident

vonbobo

not much to explain yet…

videos are great!

awjt

If we had radar pointed upwards, couldn’t we see these things coming? I think we’re too busy looking downwards with our drones and satellites to notice anything incoming.

bzishi

Apparently it came from the direction of the Sun. This is a blind spot for asteroid detection.

Asteroid detection has a fairly meager budget because there really isn’t much of a risk. The type of event that happened over Russia happens every couple of decades, usually over more remote areas or the oceans. So NASA focuses on cataloging the big ones that could have a significant impact.

Don’t let the ‘scary’ or ‘unknown’ factor cloud your judgement. Meteors are not a risk worth spending money defending against. If you spend the money building flood protection or making buildings more resistant to earthquakes then you will save a hell of a lot more lives than if you panic over whether the sky if falling.
- Naim abu darwish
  
  what’s the guarantee that it only happens in remote areas?
  - Joe Buck
    
    No guarantee, but 70% of the earth’s surface is water and the majority of the land surface is remote from human settlement. That means that 9 out of 10 strikes will be far from people.
    - Antinous / Moderator
      
      Wouldn’t that cause tsunami?
    - Jerril
      
      A sonic boom over the ocean isn’t going to cause a tsunami. Something big enough to come down all the way to hit the ocean AND be big enough and fast enough by the time it gets there to cause a Tsunami just doesn’t happen very often at all.
      
      But if it does, well. We have tsunamis already. Tsunamis from space come with as much warning as tsunamis from earthquakes.
  - bzishi
    
    Probability. There are no guarantees. Is this a satisfactory answer? Or do you want me to say “yes, there is some small probability that a Texas-sized meteor could enter the atmosphere directly above the Statue of Liberty on Independence Day?”
- http://profile.yahoo.com/CTQLXKBNNLQI7OHHNII6ZCCYAU madshad
  
  why dont they just wait for the sun to go down and then look?
  - bzishi
    
    This is a joke, right?
  - Jerril
    
    Under the assumption that the poster and the 3 likers aren’t kidding – the sun doesn’t “go down”, we turn away from it. The asteroids still come from the direction of the sun, we’ve now just got our other side pointed at the sun.
- Jonathan Colvin
  
  Two Tunguska-range events in less than 100 years = serious risk. If you figure it might cost only a few billion to tens of billions of dollars to put together a thorough sky search and develop a countermeasure it is good bang for the buck. You likely can’t stop these small (comparatively) impacts but the real danger comes from objects a hundred to a few hundred meters across. These could cause really serious effects including megatsunami, crop failures (a summer or two with no harvests = mass starvation), or small-country-wide desctruction. And may not be as rare as has been thought.
  - bzishi
    
    It is not a serious risk. You have a slightly higher risk of being killed by a meteor than by terrorism, so I would have no problem using money from anti-terrorism programs to fund asteroid and comet searches. But I don’t think this will happen. What probably will happen will be that Congress tells NASA to spend more money searching for asteroids while continuing to cut their budget. Thus, this incredibly low risk threat will cut into important space R&D. Multi-billion dollar missions to explore our Solar System will be cut so that Congress can have a probe that monitors our blind spot. After all, just like terrorism, meteors are flashy and scary.

Jonathan Colvin

“Someone is wrong on the internet”….unfortunately this time it’s Phil. The noise was NOT a “sonic boom” as is now being endlessly reported, but a 10-15 km long multikiloton explosive ablation of the bolide; essentially a long nuclear-sized explosion at high altitude. The rest of what Phil writes is mostly correct. It may seem a technical difference, but there is in fact a large difference between an explosion and a sonic boom (sonic boom is just the result of hypersonic air displacement). Perhaps Phil was just trying to make the point that it wasn’t a *ground* explosion, but still, it wasn’t a sonic boom.

duncancreamer

That seems to contradict what Wikipedia says: http://en.wikipedia.org/wiki/Meteoroid#Sounds_of_meteors

Please elucidate.
- Jonathan Colvin
  
  Umm…maybe Nature journal: http://www.nature.com/news/russian-meteor-largest-in-a-century-1.12438 ”Explosion rivalled nuclear blast”. Nature is saying hundreds of kilotons (explosion many times Hiroshima size). My multi-kiloton guesstimate was a little low. Sure as heck wasn’t a “sonic boom”… . Is “Nature” authoritative enough?
Jerril

[Updated to add: I now think these were actual explosions; please see note at the bottom of this post about this.]

Phil’s latest post says he’s changed his mind.

Jonathan Colvin

Wow. It was MUCH bigger than originally thought. Now estimate is 7000 tonnes (15 m across), 1/16 the size of 2012DA14, and 150-200 KT explosive energy release. Largest event since Tunguska. Thanks God for Russian dash cams! So, when you look up at the (small looking) smoke trail, those little puffy clouds are actually the size of large nuclear (almost thermonuclear) explosions. They look little because they are 20 -30 miles away.