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Monday, December 27, 2004

Friday The 13th, 2029 Might Be Truely Unlucky For Earth

IN WHAT could make for the blackest of black Fridays, an asteroid a quarter of a mile long has been given the highest risk of hitting the Earth ever conferred on a heavenly body.

The threat posed by object 2004 MN4 has been graded by astronomers as level four out of ten on their warning scale - the first asteroid ever to be graded higher than level one.

This means it has a one-in-45 chance of impact on Friday, 13 April, 2029. The assessment originally stood at level two.

The level-four threat posed by the asteroid is listed on the Torino scale as "a close encounter, with 1 per cent or greater chance of a collision capable of causing regional devastation".

A level-two threat is described as "a somewhat close, but not unusual encounter. Collision is very unlikely".

If 2004 MN4 collided with the Earth, it would have an estimated 1,600 megaton impact - equal to 100,000 Hiroshima atom bombs.

However, as with previous asteroid sightings, astronomers expect the threat to diminish to zero following further observations.

A spokesman for an Italian research centre that monitors the risk from newly-discovered asteroids and comets said: "Our current estimate of the probability of impact is one in 45, but this probability is only a measure of our ignorance on what really is the orbit of 2004 MN4; thus this estimate will change every time new observations are available.

"Most likely, that is in 44 cases out of 45, the impact probability will go to zero after enough new observations have been obtained and processed.

"Attention by the public and by public officials is merited if the encounter is less than a decade away."

The asteroid was discovered in June by astronomers in Arizona. However, publication of its estimated impact probability was delayed while information collected on a new instrument was checked.

Dr Donald Yeomans, manager of the Near Earth Object Program at the US space agency NASA’s jet propulsion laboratory in Pasadena, California, said: "We can’t yet rule out an Earth impact on 13 April, 2029."

Dr Yeomans continued: "In the unlikely event that it did hit, it would be quite serious. We’re talking either a tsunami if it hit in the ocean, which would be likely, or significant ground damage."

The asteroid’s estimated size - 1,320ft long - has been inferred from its brightness, which assumes that its reflectivity is similar to other asteroids that have been observed.

Dr Alan Fitzsimmons, an astronomer at Queen’s University Belfast, advised the Near Earth Object Information Centre in Leicester that the object would remain observable until summer 2005 and will be observable on many more occasions before the potential impact date.

"This will allow scientists a good window of opportunity to continue observations and refine their understanding of the asteroid’s orbit," he said.

Astronomers expressed concern last year that reports of potential asteroid collisions with the Earth were causing unnecessary panic.

Source: The Scotsman


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