Putting the Russian meteorite in perspective

Friday morning, a large meteor entered the atmosphere over the southern Ural area of Russia, detonating with enough force to shatter windows in nearby towns and injure over 1000 people.  Preliminary estimates suggest an impactor traveling at 15 to 20 km/s, and weighing 8000 to 10,000 tons, exploding at an altitude of 20-30 km with the force of a nuclear weapon.

These are hard numbers to wrap one’s head around.

Let’s start with the size. There are numerous reports around on the bolide being “bus sized.”  But buses are not made of solid rock, so this is deceptive. In this situation, mass is more important than dimensions. A bus weighs about 15-20 tons. That’s a lot less than 8000-10,000.  For example, 8000-10,000 tons is the approximate size of the naval destroyer USS Cole, which was famously attacked by Al Qaeda in Yemen in 2000. It’s a lot bigger than a bus. Of course, that ship doesn't fly in space.  Rather, it sails in the ocean at about 50 km/ hour, thousands of times slower than 20 km/ second. The International Space Station is about 450 tons.

Orbital velocity for a low earth orbit is about 8 km/second, and reentry speeds returning from low earth orbit are similar.  So this meteor was traveling at about twice orbital speed when it hit the atmosphere.  This is substantially faster than the 11 km/s reentry of the Apollo missions returning from the moon, and about twice as fast as the space shuttles (and other low earth orbit spacecraft) re-enter.  It is about 50 times faster than a handgun bullet.

The total energy released, between a quarter and a half a megaton, was similar to a modern H-bomb.  However, it was more dispersed, and released high in the atmosphere. Because the impactor was traveling at twice orbital speed, the energy would be equivalent to an orbital object of four times the mass re-entering.  32,000 to 40,000 tons is about the size of the Titanic, or a WWII battleship. 

Something similar to this has been imagined.  Below is a model of CV-6, the famous 20,000 ton WWII aircraft carrier Enterprise.

Compare that to the fictional NCC 1701 spaceship enterprise, at the same scale.

The internet gives a spaceship mass of 10 times the aircraft carrier, which seems way to heavy to be sensible. 

If we say the spaceship is twice the mass of the aircraft carrier (it is bigger, after all, even if it is also probably made from a lighter & stronger material than steel), then it would have about the same energy on re-entry as the Chelyabinsk bolide.

We can compare the videos:

Star Trek III

Chelyabinsk Friday morning:

Reality is still far more gripping than imagination. 

Finally, here is what the Earth looked like from the asteroid’s point of view an hour before impact.  A few things to note:

First, the Earth is almost full.  As a result, the side of Earth facing the asteroid was in day, so it would have been hard to spot, as the sun was behind it.  However, the US space junk tracking radars in Hawaii should have been able to pick it up.  I wonder if they did, if they passed any sort of a warning on, or even are they allowed to?  It would be a shame if the 1200 injuries that occurred were preventable, but for American government red tape.

I build huge cans of learning named after a small pink water animal with lots of legs.

I build huge cans of learning named after a small pink water animal with lots of legs. The can of learning fires the tiniest bits of air, hurried up by a field, at rocks to break them into the tiniest bits of matter. We suck all of the air out of the box, leaving only empty space. That way the bits of the rock don't hit bits of air that are in the way.

Another field sucks these bits off of the face of the rock, and into a big box filled with empty space and more fields.  The fields in the box sort the bits by exactly how heavy they are. The force that holds the bits together makes them a little bit lighter, so knowing exactly how heavy they are lets us tell tiny bits holding on to each other from single other tiny bits that are slightly lighter or heavier.
The very heavy bits are actually too big to hold themselves together. So they fall into pieces over time.  We look at how many pieces there are. This tells us the age of the rock.
People wonder how old rocks are.  My business builds cans of learning to tell them.

Brief: Explain your technical job using only the 1000 most common words #upgoerfive

Thanks to Anne and Chris for the brief.

The world has ended, but this blog rambles on.

In this timezone, it’s the 21^st of December already, and the world has been destroyed.

Sorry guys, but the Mayans were right.  At 12:01 am, Eastern Australian Daylight time, this section of the world was destroyed.  The planet is disintegrating along the time-zone lines like the segments of an orange getting peeled off and tossed into a juicer.  Sorry folks, it’s all over.  And they didn’t even use my method for destroying the planet.

Fortunately, the super expensive Australian National Broadband Network is extensive and robust enough to survive this catastrophe, so I am still able to blog from the cosmic void.  It is getting cold and hard to breathe out here, but there are some benefits.  For example, without a globe there is no global warming.  And, in space, no-one can hear your neighbor throw up in the front lawn after a big night out.  And the big night will last forever.  Unfortunately, the nearest place to grab a drink is now the Saturnian moon Titan.  No word from the Mayans yet on when that baby is due to go.

Odd-shaped lakes in Google Earth

I was goofing around in Google Earth this evening, performing an activity that started out as meaningful and quickly degenerated into a Game of "Ooh what's that", when I came across the following:
Note the very strange shoreline on this lake, with numerous straight line borders. The first time I saw this, I thought I was looking at some dams I didn't know about, but I quickly realized that such an interpretation made no sense.

 Instead, what I believe this image is showing is a mosaic from pictures acquired several years apart. One of those years was a wet year, while another must have been after a period of extended drought. As a result, the lake is ~90% full in some of the images, but almost empty in others. And the straight-line lakeshores are just the tile borders, which Google's new color autocorrect makes less obvious.

 I have no idea where WoGE is up to these days, but I left the co-ordinates off in case anyone wants to chase up the Reservoir.

Pre-Proterozoic Political Proletariat

For those not familiar with old Earth geology, the conglomerates of the Jack Hills contain detrital zircons, and the 1% of those zircons which are older than 4 billion years consume 95% of the resources used to study these mineral grains. Clearly, this is the longest-running example of economic inequality on this planet.

The trouble with climate models

For the past 20 years or so, people who have not wanted to consider the possible issues relating to increasing the atmospheric load of carbon dioxide and other IR-adsorbing gasses have tried to play down the dangers of potential climate change by pointing out that the computer models used to predict it were not very accurate.

The implication behind this argument is that the uncertainty in these models will overestimate potential changes. What will happen in a future where the models underestimate climate changes in generally unmentioned.

Luckily, we don't need to look to the future to investigate that possibility anymore. The above graph (from Neven's excellent Sea Ice Blog) shows the actual decline in summer arctic sea ice, relative to various computer model predictions. As this graph shows, ice is now melting much faster than any of the models had predicted.

Oops.

Of course, the most persistent pro-pollution propagandists tell us that this proves that the computer models are useless, which means that climate change can't be real, which means that any effects we see must be caused by the warming fairies instead of exhaust gasses.

Whatever.

What we, as scientists, would really like is this: We would like to be able to predict the effects of pollution on the climate before they happen. That's why we get into science. The whole purpose of the field is to make predictions about the natural world and then test them. So if y'all cook the Earth faster than we can make decent predictions about the warming, then we get very disappointed. Not as disappointed as all the retirees on the Jersey Shore who just lost their houses, but still not real happy. So folks, here is a request.

Could y'all please slow down the warming of the planet just enough so that we, the research community, can actually catch up and figure out who is happening to this atmosphere?We would much rather predict doom and gloom for the future than look at last week's disaster and shrug , "Yeah. We should have thought of that."

It has been a year since the solar panels on our house were installed. In that year, we consumed about 2750 kWh of electricity, and produced about 3370 kWh.

If only politicians led by example

How great would it be if all the politicians running for office cancelled any new TV ad buys, and donated the money to hurricane relief instead?  With an estimated 6 billion dollar price tag for this year's elections, a the damages inflicted by Frankenstorm Sandy will still need additional funding, but it would certainly make a dent in the enormous damages that stretch across half the eastern seaboard and west through the Appalachians.  And putting that money into building new homes, fixing infrastructure and preparing the nation for the next superstorm would be a far better use than 2000 more hours of cheezy attack ads being beamed into space.  Sure, some of those ad buys have been paid for already- but visionary candidates, parties, and PACS can choose to run public service ads in that time.

Seriously, folks.  If takes just one candidate to tell all his supporters to fund the red cross instead of him, and suddenly his opponent is turned into the Grinch if he buys attack ads instead of charity appeals.  So which American leader is going to step up first?