Phhew!!

[Sarongman]

The asteroid we've all been watching has passed harmlessly by. That rock was the size of a football field, however the sneaky little devil that hit Russia was only the size of a small car. It's interesting how the "biggies" of our time have hit Russia; Tunguska, in Siberia, was a fair bit bigger, but still not on the scale of what just passed us, INSIDE the orbit of some communication satellites. The real doozy was the one that created the Gulf of Mexico a few million years back---Ah yes, I remember it well

This has got me hunting in my chaotic library for an interesting book, entitled "When the Earth Nearly Died" which sets out the theory that we have been hit by a killer one about 12000 ( or thereabouts) years ago, and postulates that it is from that event that we get the many stories of floods and fires caused by whatever deity's wrath. Being, at present, unable to access it, I am re-reading the Flem Ath's book "When the Sky Fell".

Goodnight kiddies, sweet dreams

[crfriend]

The asteroid we've all been watching has passed harmlessly by. That rock was the size of a football field, however the sneaky little devil that hit Russia was only the size of a small car. It's interesting how the "biggies" of our time have hit Russia [...]

Statistically, Russia would tend to pick up the most junk as it's got the largest land area. Unless it caused a tsunami, I suspect nobody'd care if such stuff fell into the ocean.

I forget the exact number, but I believe that Earth picks up several tons of mass per day by scooping junk out of space. Most of this, of course, burns up harmlessly in the atmosphere and settles to the ground as dust. Once in while, however, a big/dense chunk makes it all the way to the ground and makes a mighty mess of whatever it happens to hit; little bits just punch holes in roofs or put craters in the landscape -- it's the biggies that cause concern.

This one wasn't really a threat; the figures I saw put it at about 17,000 miles out. The original forecast from a couple of days ago put it at about 400 miles -- pretty much the orbit distance of the GPS constellation; but, even 17,000 is inside the orbit of the geosynchronous satellites which are about 22,000 miles out. The nice thing about space is that it's big and we're a small target.

[Sinned]

I seem to remember from my childhood that a certain Chicken Licken winged about the sky falling in because of a hard object falling to ground via the bonce. Came to nothing then!

[Sarongman]

I certainly wasn't w(h)ing(e)ing Sinned, just fascinated with the whole thing. What is good is that, with computing technology we have today, we can so precisely track the trajectory of these objects. 'Scuse me, but I have to go and find a nice unsuspecting hen!

Carl, 17000 miles is still the equivalent of hearing the bullet whistle past the ear. Just a few degrees difference----! We haven't been hit by a catastrophic size yet, but the odds shorten, don't they?

[skirted_in_SF]

There is an interesting picture distributed by Associated Press of the hole punched in lake ice by the Russian meteorite. Based on the comparing to the people standing near it, I would guess the hole is about six meters in diameter.
BTW, the accompanying article in the Wall Street Journal says that 100 tons of dust and sand size particles are added to the earth daily from space.

[Caultron]

Most of the damage was apparently caused by the shock wave of the meteor dropping through the atmosphere and burning up, and not from the meteor itself.

[Sarongman]

I've just studied NASA figures, and a DA14 size rock passes close about every 40 years. It also said that a hit happens every 1200 years. These hits happened in more primitive parts of the planet, as both Western and Ottoman civilisations were recording events closely, and geologists can date ground phenomena. All just fascinating as far as I am concerned.

As for the sonic boom, yes, that can create some havoc. I remember a Mythbusters programme where they got USAF planes to fly, at supersonic speed, close to a shed with windows, and the damage was quite considerable, including buckling of the structure as well as the window glass flying. Glass fragments were the main cause of injury in the Russian incident.

[crfriend]

Carl, 17000 miles is still the equivalent of hearing the bullet whistle past the ear. Just a few degrees difference----! We haven't been hit by a catastrophic size yet, but the odds shorten, don't they?

I was operating under the "a miss is as good as a mile" rule. But, yes, the odds of a serious strike do shorten as time progresses.

BTW, the accompanying article in the Wall Street Journal says that 100 tons of dust and sand size particles are added to the earth daily from space.

So it's about a hundred. I was off by some. In any event, the number is miniscule compared to our planetary mass, our planet having cleared most of its orbit of the big junk billions of years ago. It must've been a wild knockabout time when that was going on!

On sonic booms: I recall those from my very young days and always thought they were pretty cool -- from a distance. Close in, they did cause damage, and that finally forced lawmakers to ban supersonic flight over land (except in conditions of "extreme emergency" of course). It's quieter now. Recall that a sonic boom is multispectral in its content; there's a strong high-frequency component in it which contributes to the shattering effects and there's also a very large infrasonic component that causes deformation and buckling of things. I missed that episode of Mythbusters, but would like to have seen it.

In the case of the recent meteor incident in Russia, I head one woman talking to the BBC about the event and she described the bright light from outside and several moments later the blast. Personally, if I saw something like that I'd be diving for cover if at all possible. If something is hot enough to be emitting bright white light there will most likely be a blast following.