posted 07-24-2002 01:23 AM               

Space rock 'on collision course'

By Dr David Whitehouse
BBC News Online science editor

An asteroid discovered just weeks ago has become the most threatening object yet detected in space. A preliminary orbit suggests that 2002 NT7 is on an impact course with Earth and could strike the planet on 1 February, 2019 - although the uncertainties are large.

Astronomers have given the object a rating on the so-called Palermo technical scale of threat of 0.06, making NT7 the first object to be given a positive value. From its brightness, astronomers estimate it is about two kilometres wide, large enough to cause continent-wide devastation on Earth.

Many observations

Although astronomers say the object definitely merits attention, they expect more observations to show it is not on an Earth-intersecting trajectory

It was first seen on the night of 5 July, picked up by the Linear Observatory's automated sky survey programme in New Mexico, US. Since then astronomers worldwide have been paying close attention to it, amassing almost 200 observations in a few weeks.

Dr Benny Peiser, of Liverpool John Moores University in the UK, told BBC News Online that "this asteroid has now become the most threatening object in the short history of asteroid detection". NT7 circles the Sun every 837 days and travels in a tilted orbit from about the distance of Mars to just within the Earth's orbit.

Potential devastation

Detailed calculations of NT7's orbit suggest many occasions when its projected path through space intersects the Earth's orbit. Researchers estimate that on 1 February, 2019, its impact velocity on the Earth would be 28 km a second - enough to wipe out a continent and cause global climate changes.

However, Dr Peiser was keen to point out that future observations could change the situation. He said: "This unique event should not diminish the fact that additional observations in coming weeks will almost certainly - we hope - eliminate the current threat."

Easily observable

According to astronomers, NT7 will be easily observable for the next 18 months or so, meaning there is no risk of losing the object. Observations made over that period - and the fact that NT7 is bright enough that it is bound to show up in old photographs - mean that scientists will soon have a very precise orbit for the object.

Dr Donald Yeomans, of the US space agency's (Nasa) Jet Propulsion Laboratory in California, told BBC News Online: "The orbit of this object is rather highly inclined to the Earth's orbit so it has been missed because until recently observers were not looking for such objects in that region of space."

posted 07-24-2002 10:48 PM               

Space rock should be visible through binoculars, experts say

By Robert Roy Britt
SPACE.COM

July 23 — In a rare event slated for mid-August, an asteroid will pass close enough to Earth to be visible through binoculars and small telescopes.

THE GIANT BOULDER, named 2002 NY40, was discovered about a month ago.

On Aug. 18, the asteroid will be 327,200 miles (526,600 kilometers) from Earth, according to the Minor Planet Center in Cambridge, Mass. That will put it well beyond the moon’s orbit. The asteroid’s exact size is not known, but it is “somewhat smaller than 1 kilometer (0.62 miles) in diameter,” said Gareth Williams, associate director of the center.

Rough estimates by astronomers have put the asteroid at 547 yards (500 meters) wide. A pair of Louisiana Superdomes would fit inside an object this size, with ample room left over for parking.

NOT VISIBLE TO NAKED EYE

Asteroid 2002 NY40 should brighten to about magnitude 9.3 on Aug. 18, Williams told Space.com. The faintest objects visible to the unaided eye are around magnitude 6.0, on a scale where larger numbers indicated dimmer objects. The brightest stars in the sky are typically categorized as zero or first magnitude.

posted 07-27-2002 05:14 PM               

25.07.2002
By GREG ANSLEY Australia correspondent

CANBERRA - As the BBC reported yesterday that a continent-killing asteroid was racing toward Earth, an Australian physicist was speculating on an even more hair-raising probability - ghost comets we cannot see coming.

The BBC's report that the 2km-wide asteroid 2002 NT7 could slam into the planet on February 1, 2019, is bad enough.

Striking at 28km a second, the impact would be powerful enough to destroy a continent and cause global climate changes, although scientists optimistically hope further observations may show 2002 NT7 will miss the planet.

But in Australia, Dr Robert Foot, of the University of Melbourne, has just published a book, Shadowlands: quest for mirror matter in the Universe, which suggests we may never see our doom approaching.

Foot theorises that invisible comets made of a substance called mirror matter are spinning through space and may already have collided cataclysmically with Earth.

More, there may be entire solar systems with their own suns, planets and forms of life that are invisible to humans or their instruments, apart from a possible explanation for the equally mysterious "dark matter" scientists suggest may be the cosmic framework of the universe.

"It certainly seems fantastic," Foot said yesterday. "But so did antimatter. Before antimatter was discovered experimentally it was [also] a theoretical idea."

Antimatter is a substance comprised of atoms that have the mass and charge of ordinary electrons, protons or neutrons, but which have opposite charge and cannot exist close together.

The theory of mirror matter has been debated for decades, based on the apparent lack of symmetry in the interaction of particles such as electrons, protons and photons.

Instead of the balance that nature normally demands, the interactions are mainly left-handed, leading Foot and other physicists to argue the mathematical probability of mirror particles, invisible and unable to interact with ordinary particles but providing essential symmetry.

Foot suggests there may be dramatic evidence of the existence of mirror matter.

A large number of comets vanish after orbiting the sun because, astronomers commonly believe, their volatile gases and ice are burned off, leaving inert rocks like asteroids.

But United States researchers recently calculated that the number of dormant comets or asteroids being discovered was about 100 times less than there should be.

"One idea is that these comets could be mirror matter bodies with a bit of ordinary matter in them," Foot said.

"The ordinary matter gets burned off and you're left with this mirror matter core, which is virtually invisible." This could explain the destruction of 2100 sq km of forest around Tunguska, Siberia, in 1908, generally attributed to an asteroid strike.

But scientists have been unable to find a crater, evidence of meteor fragments or even significant chemical traces.

Similarly, a ball of light streaked across the sky above Jordan in April last year, split into two and slammed into a hill, scorching earth and trees, but left no crater. Foot believes if mirror matter does exist, proof may lie in Siberia and Jordan.

He said tonnes of the matter could lie beneath the surface of the impact zones, so far undiscovered but probably detectable through thermal imaging and chemical tests.
http://www.nzherald.co.nz/storydisplay.cfm?storyID=2197017&thesection=news&thesu bsection=world

posted 07-27-2002 05:25 PM            

Also I agree with the theory about mirror matter. much like those strange objects that we found in the solar figures that seemed to have an uncanny reflective illumination. This illumination and the shadow were on opposite sides which in fact did not correspond with the position and radiance of the sun. They almost seemed as if they were normally transparent but may have been caught in an anomalous beam or field which exposed them.

quote:

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probably detectable through thermal imaging

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posted 07-29-2002 02:21 PM               

Asteroid to miss - this time around

By Dr David Whitehouse
BBC News Online science editor

Astronomers have ruled out an Earth impact from asteroid 2002 NT7 on 1 February 2019 - but they say, as yet, future collisions have not been completely excluded.

2002 NT7, a two-kilometre-wide (1.4 miles) chunk of rock, was discovered on 9 July.

Initial estimates of its orbit suggested there was a small chance of it colliding with our planet in 17 years' time. However, the latest observations accumulated over the last few days have confirmed the asteroid will fly harmlessly by.

Dr Don Yeomans, of the US space agency's (Nasa) Jet Propulsion Laboratory, said: "We can now rule out any impact possibilities for 1 February 2019."

Uncharted space

But further work needs to be done to confirm that 2002 NT7 is not a threat further into the future. Dr Yeomans added: "While we cannot completely rule out an impact possibility for 1 February 2060, it seems very likely that this possibility will soon be ruled out as well."

Analysts expect that it will be several more weeks before new observations allow a much better picture to emerge about 2002 NT7's future movements. This is because no past observations - that could be used to pinpoint its trajectory - have been found in astronomical archives. This is because the asteroid's unusual orbit takes it into regions of space that are seldom surveyed. But astronomers say that their concern about 2002 NT7 has not evaporated completely.

Media debate

According to Dr Benny Peiser, of Liverpool John Moores University, UK, we should not be celebrating too quickly. "It would be prudent to caution interested observers that further observations in the near future could result in new impact dates," he told BBC News Online. "There is even a very small possibility that the next set of observations may lead to new impact dates and a prolonged period of fluctuating impact probabilities, before the object will eventually be dropped," he said.

The intense worldwide interest in 2002 NT7 has prompted a debate in the astronomical community. Following the object's discovery, and the realisation that it could strike the Earth in 2019, astronomers decided to make no announcement whilst they monitored the situation.

posted 07-29-2002 02:44 PM            

quote:

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Some astronomers have been unhappy with what they see as alarmist reporting in the media, and they say that the policy on public disclosure of such information should be reviewed.

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Who are these astronomist to decide what we should 'know' or how we should 'react' to such findings? This is democracy?