"At 50m it wouldn't do much, but a direct hit on a city like...

"At 50m it wouldn't do much, but a direct hit on a city like Perth might be a bit nasty."

There wouldn't be much left of Perth if it received a direct hit.


For those interested in how much damage would occur, if an asteroid this size hit land, here is what Nasa has to say:

""2012 DA14 is a fairly typical near-Earth asteroid. It measures some 50 meters wide, neither very large nor very small, and is probably made of stone, as opposed to metal or ice. Yeomans estimates that an asteroid like 2012 DA14 flies past Earth, on average, every 40 years, yet actually strikes our planet only every 1200 years or so.

The impact of a 50-meter asteroid is not cataclysmic--unless you happen to be underneath it. Yeomans points out that a similar-sized object formed the mile wide Meteor Crater in Arizona when it struck about 50,000 years ago. "That asteroid was made of iron," he says, "which made it an especially potent impactor." Also, in 1908, something about the size of 2012 DA14 exploded in the atmosphere above Siberia, leveling hundreds of square miles of forest. Researchers are still studying the "Tunguska Event" for clues to the impacting object."


Personally, I wouldn't want to be within 70km of such a strike. If it hit a highly populated city such as New York the results would be felt for many years given the financial debacle which would ensue, then again it could hit Washington or even Canberra, and the result might actually be dynamic...

Here are a couple of descriptions from those living at the time of the Tunguska event:

""The first report of the explosion was in the Irkutsk paper dated July 2, 1908, published two days after the explosion:

...the peasants saw a body shining very brightly (too bright for the naked eye) with a bluish-white light.... The body was in the form of 'a pipe', i.e. cylindrical. The sky was cloudless, except that low down on the horizon, in the direction in which this glowing body was observed, a small dark cloud was noticed. It was hot and dry and when the shining body approached the ground (which was covered with forest at this point) it seemed to be pulverized, and in its place a loud crash, not like thunder, but as if from the fall of large stones or from gunfire was heard. All the buildings shook and at the same time a forked tongue of flames broke through the cloud.

All the inhabitants of the village ran out into the street in panic. The old women wept, everyone thought that the end of the world was approaching (Kridec 1966).

S.B. Semedec, an eyewitness in the village of Vadecara about 60 km south of the explosion site, provided excellent information:

...I was sitting in the porch of the house at the trading station of Vadecara at breakfast time...when suddenly in the north...the sky was split in two and high above the forest the whole northern part of the sky appeared to be covered with fire. At that moment I felt great heat as if my shirt had caught fire; this heat came from the north side. I wanted to pull off my shirt and throw it away, but at that moment there was a bang in the sky, and a mighty crash was heard. I was thrown to the ground about three sajenes [about 7 meters] away from the porch and for a moment I lost consciousness.... The crash was followed by noise like stones falling from the sky, or guns firing. The earth trembled, and when I lay on the ground I covered my head because I was afraid that stones might hit it (Kridec 1966)."

Wikipedia's description of the power of the explosion at Tunguska:

"Although the meteoroid or comet appears to have burst in the air rather than hitting the surface, this event still is referred to as an impact. Estimates of the energy of the blast range from 5 to as high as 30 megatons of TNT (21–130 PJ),[7][8] with 10–15 megatons of TNT (42–63 PJ) the most likely[8]—roughly equal to the United States' Castle Bravo thermonuclear bomb tested on March 1, 1954; about 1,000 times more powerful than the atomic bomb dropped on Hiroshima, Japan; and about two-fifths the power of the later Soviet Union's own Tsar Bomba, the largest nuclear weapon ever detonated."

It is unknown exactly what caused the Tunguska event, however the article from the quote above, believes it was most likely a comet and currently there is one on the way called ISON which may well turn out to be 'The Comet of the Century'.

""The fact that ISON can already be seen means it may be reasonably large — perhaps a couple of miles across — which suggests that when it dips to less than a million miles (1.6 million km) above the Sun’s fires next November 28, it may be robust enough to avoid the breakup that often happens to smaller comets. And if it does survive, ISON could go on to light up the night sky in the Northern Hemisphere for much of December, 2013 and on into January.

Comet experts are also making much of the fact that ISON’s path is very similar to that of Kirch’s Comet, a.k.a. Newton’s Comet, a.k.a. the Great Comet of 1680, which was bright enough to be seen in daylight and had a magnificently long tail (it was also the first comet ever discovered with a telescope). It’s not the same object, but it’s quite possible that both are chunks of a much larger body that broke apart long ago, maybe during its own passage through the inner solar system. The fact that such larger bodies exist isn’t in doubt: Pluto, for example, is essentially a gigantic chunk of dirty ice."

http://www.icr.org/research/index/researchp_sa_r05/

http://science.time.com/2012/12/20/coming-in-2013-the-comet-of-the-century/

http://en.wikipedia.org/wiki/Tunguska_event