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Stealth Asteroid Misses Earth
Paradoxish writes: "Gah. According to cnn.com an asteroid hiding in an astronomical blindspot nearly blindsided Earth. The scary part is that scientists didn't notice it until four days AFTER it passed by. Apparently, it would've been similiar to the Tunguska explosion. Scary." As long as they keep missing Earth, we're OK.
From space.com:
Almost no one lived near blast site, however, save a few hunters and trappers. No one studied the site until 1930. And while scientists have long presumed an asteroid or comet exploded just above the surface, no consensus has been reached. Some even suggested a miniature black hole did the work.
The object seems to have approached Tunguska from the southeast at about 11 km per second (7 miles a second), the BBC reported.
Why did the asteroid break apart in the air?
"Possibly because the object was like asteroid Mathilde, which was photographed by the passing Near-Shoemaker space probe in 1997," researcher Luigi Foschini told the BBC. "Mathilde is a rubble pile with a density very close to that of water. This would mean it could explode and fragment in the atmosphere with only the shock wave reaching the ground."
A scientific paper on the work will be published in an upcoming issue of Astronomy & Astrophysics.
From bbc.co.uk:
They analysed seismic records from several Siberian monitoring stations, which combined with data on the directions of flattened trees gives information about the object's trajectory. So far, over 60,000 fallen trees have been surveyed to determine the site of the blast wave.
Over 60,000 fallen trees have been surveyed to determine the site of the blast wave
"We performed a detailed analysis of all the available scientific literature, including unpublished eye-witness accounts that have never been translated from the Russian," said Dr Foschini. "This allowed us to calculate the orbit of the cosmic body that crashed."
The object appears to have approached Tunguska from the southeast at about 11 km per second (7 miles a second). Using this data, the researchers were able to plot a series of possible orbits for the object.
Of the 886 valid orbits that they calculated, over 80% of them were asteroid orbits with only a minority being orbits that are associated with comets.
This doesn't make sense.
You have to make assumtions - for example change the path, speed and time when/where the asteroid had to be to hit earth. Where on earth it hits, depends on those assumtions and because there are millions of possible assumtions that lead to this result, you get millions of possible targets on earth.
This is like asking what number would have hit a dart player who missed.
since it's spring here now, and the asteroid is probably in the ecliptic.
That would be summer. In spring any location is possible.
The flashes from nuke detonations have certain characteristics that the flashes from asteroid/cometary fragment detonations don't.
(That said, the nuke-detecting satellites are doing a good job of keeping track of upper-atmosphere flashes from asteroid/cometary fragments. To the extent that such data can be given to NASA folks, we're getting some good science out of these things.)
Yes, a human observer on the ground may erroneously conclude they've been nuked, but any rational chain of command involving release of nuclear weapons will include verification that the supposed nuke really was a nuke and not an unfortunately-timed meteorite.
(Unfortunately, convincing the other side's troops that we hadn't developed some sort of new superweapon might be another story. The less technologically-advanced the opponent, the more the risk that they'll be able to understand the evidence that it was just Really Bad Luck.)
Thankfully, the odds of asteroid impact itself are pretty slim, and I'm much more worried about those odds - anywhere on the planet - than I am about the rock hitting the Wrong Place at the Wrong Time.
(Also thankfully, the solution to both problems is the same - a bit more spent on gear to watch for rocks, and assloads more spent on R&D into cheap, heavy-lift capabilities so we have a hope in hell of deflecting them when/if we find one with our name on it. If we never find a rock with our name on it, we've got a heavy-lift capability to make space tourism, offworld solar power stations, and eventual colonization a reality. Win/win.)
The rating goes from zero (the object is certain to miss the Earth) to ten (the nasty asteroid thingy is definitely going to "cause a global climatic catastrophe"). Read it, it's very unsettling...
Does anyone know what Torino rating this most recent near-miss was?