nzalendo
JF-Expert Member
- May 26, 2009
- 11,742
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Lile jiwe nililowafahamisha mwaka jana tayari liko karibu sana na dunia na pia laweza kuonekana katika vifaa vya NASA.
Just so you know: an asteroid could hit Earth on 21 September 2030
For the first time ever, scientists are pinpointing the time of an impact that could unleash a force 100 times greater than Hiroshima, writes Robin McKie
Scientists have put a date to Armageddon. It will occur on 21 September 2030, when earth is in danger of being hit by an asteroid.
The newly discovered threat to global civilization is called 2000 SG344, and it could strike our planet with a force 100 times greater than that released by the atom bomb that destroyed Hiroshima, astronomers have calculated.
Their announcement, posted yesterday on the internet by the International Astronomical Union, is the first formal public prediction of a potential collision with a piece of cosmic debris and it arises from a scientific review process designed to eliminate premature predictions of celestial calamities.
Two years ago, asteroid watchers triggered worldwide alarm by announcing that a mile-wide asteroid called XF-11 might hit earth in 2028. A few days later they had to withdraw the forecast, after calculations showed the object posed no danger to our planet.
The new prediction is unlikely to be withdrawn, however - for it has been carefully duplicated by scientists at several research centres. The object was recently discovered trailing in Earth's orbit around the sun by astronomers using the 3.6-metre Canada-France-Hawaii telescope on the island of Hawaii.
However, the probability that it might hit Earth in 2030 was not realised until last week when Paul Chodas, at Nasa's Jet Propulsion Laboratory, began studying its orbit. There was a small but definite risk, about one in 500, that its orbit, and Earth's, might coincide on 21 September 2030 - a danger that has been verified over the past 72 hours by a group of International Astronomical Union experts in Italy, Finland and the US.
'This is a first for us,' said space scientist David Morrison at Nasa's Ames Research Center, chairman of the Astronomical Union committee. 'We have never before had a prediction at this high level of probability. In the past we have talked about 1 in 10,000 or 1 in a million.'
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On a newly devised 10-point scale for grading potential impact hazards, known as the Torino scale, the object gets a rating of only 1 - mainly because of its relatively small size and uncertain chances of striking Earth. Any rating on the Torino scale means an object merits careful monitoring. This is the first astronomical object to be given full, formal designation on the Torino scale.
In revealing their concerns, astronomers are walking a delicate tightrope between prudent secrecy and disclosure, balancing possible ridicule against the demands of public responsibility. The danger of having to make an embarrassing withdrawal about their claim is low, however, thanks to the quick action of the the technical review panel which has confirmed Chodas's calculations, and by the careful conservative language used in their announcement.
It is quite possible, say the astronomers, that SG344 may prove to be nothing more than a discarded Saturn rocket booster, lost in space since the days of the Apollo moon programme. Nasa records show that nine Saturn V rockets were launched toward the moon in the Apollo programme. In each case, spent rocket boosters ended up in uncharted orbits around the sun. If SG344 was to turn out to be one of these, it would simply burn up on entering our atmosphere.
'It could be an old rocket we sent up to launch a satellite decades ago that has come back to haunt us,' said Brian Marsden, director of the Minor Planets Center at the Smithsonian Astrophysical Observatory in Cambridge. 'At least, we can't exclude the possibility.'
However, most experts believe the SG344 is most probably an asteroid - with a diameter of between 100 and 230 feet, the size of an office block. If such an object were to hit Earth, the consequences would be severe, though not globally devastating.
Advertisement
If made of stone and iron, as are many asteroids and meteorites, SG344 would explode with an estimated energy of two megatons, But if it was a loose conglomeration of stones and gravel, as several experts believe may the case, it might easily disintegrate as it skims into the atmosphere.
Unfortunately, not enough is known about the asteroid. 'That is our problem - we don't know what it is," said Donald Yeomans, manager of Nasa's Near Earth Object Program office at JPL. 'All we know is how bright it appears to be, and so we have to guess to come up with a diameter.'
It is thought that there are more than 100,000 asteroids of the estimated size of SG344 scattered around the solar system. A few approach the Earth, and on average one strikes our planet every 100 years, the last resulting in the 20-megaton blast that levelled 700 square miles of forests of central Siberia in 1908, the Tunguska explosion. A blast like that in a heavily developed area - California or Japan - could result in millions of deaths.
In the next few months, astronomers will try to gather more data about SG344 in a bid to learn more about its orbit and to determine more accurately its chances of hitting earth - though they have had little success so far.
Future observations may yield better data, however, allowing scientists to predict more accurately its chances of striking earth.
But the object is slowly moving away from us, which means astronomers have only a short time to gather more data and so refine their orbital calculations. If they fail, they will have to wait until 2028, when SG344 comes into range again.
In such circumstances, earth will have very little time to act if it turns out that the asteroid is doomed to collide with us.
"My own feeling is that an object this small would not be worth a great effort to deflect it, even if it is on course toward Earth,' added David Morrison.
'I don't see an argument for any sort of crash effort.'
It remains to be seen if people agree in 2030.
...it happened before: our planet is struck regularly by objects crashing down on us from outer space. The best recorded of these events occurred in 1908 when a small asteroid, about 300 feet in diameter, exploded high above the Tunguska River valley in Siberia, producing a brilliant blue fireball that knocked people off their feet 40 miles away, and flattened millions of trees.
Just so you know: an asteroid could hit Earth on 21 September 2030
For the first time ever, scientists are pinpointing the time of an impact that could unleash a force 100 times greater than Hiroshima, writes Robin McKie
Scientists have put a date to Armageddon. It will occur on 21 September 2030, when earth is in danger of being hit by an asteroid.
The newly discovered threat to global civilization is called 2000 SG344, and it could strike our planet with a force 100 times greater than that released by the atom bomb that destroyed Hiroshima, astronomers have calculated.
Their announcement, posted yesterday on the internet by the International Astronomical Union, is the first formal public prediction of a potential collision with a piece of cosmic debris and it arises from a scientific review process designed to eliminate premature predictions of celestial calamities.
Two years ago, asteroid watchers triggered worldwide alarm by announcing that a mile-wide asteroid called XF-11 might hit earth in 2028. A few days later they had to withdraw the forecast, after calculations showed the object posed no danger to our planet.
The new prediction is unlikely to be withdrawn, however - for it has been carefully duplicated by scientists at several research centres. The object was recently discovered trailing in Earth's orbit around the sun by astronomers using the 3.6-metre Canada-France-Hawaii telescope on the island of Hawaii.
However, the probability that it might hit Earth in 2030 was not realised until last week when Paul Chodas, at Nasa's Jet Propulsion Laboratory, began studying its orbit. There was a small but definite risk, about one in 500, that its orbit, and Earth's, might coincide on 21 September 2030 - a danger that has been verified over the past 72 hours by a group of International Astronomical Union experts in Italy, Finland and the US.
'This is a first for us,' said space scientist David Morrison at Nasa's Ames Research Center, chairman of the Astronomical Union committee. 'We have never before had a prediction at this high level of probability. In the past we have talked about 1 in 10,000 or 1 in a million.'
Advertisement
On a newly devised 10-point scale for grading potential impact hazards, known as the Torino scale, the object gets a rating of only 1 - mainly because of its relatively small size and uncertain chances of striking Earth. Any rating on the Torino scale means an object merits careful monitoring. This is the first astronomical object to be given full, formal designation on the Torino scale.
In revealing their concerns, astronomers are walking a delicate tightrope between prudent secrecy and disclosure, balancing possible ridicule against the demands of public responsibility. The danger of having to make an embarrassing withdrawal about their claim is low, however, thanks to the quick action of the the technical review panel which has confirmed Chodas's calculations, and by the careful conservative language used in their announcement.
It is quite possible, say the astronomers, that SG344 may prove to be nothing more than a discarded Saturn rocket booster, lost in space since the days of the Apollo moon programme. Nasa records show that nine Saturn V rockets were launched toward the moon in the Apollo programme. In each case, spent rocket boosters ended up in uncharted orbits around the sun. If SG344 was to turn out to be one of these, it would simply burn up on entering our atmosphere.
'It could be an old rocket we sent up to launch a satellite decades ago that has come back to haunt us,' said Brian Marsden, director of the Minor Planets Center at the Smithsonian Astrophysical Observatory in Cambridge. 'At least, we can't exclude the possibility.'
However, most experts believe the SG344 is most probably an asteroid - with a diameter of between 100 and 230 feet, the size of an office block. If such an object were to hit Earth, the consequences would be severe, though not globally devastating.
Advertisement
If made of stone and iron, as are many asteroids and meteorites, SG344 would explode with an estimated energy of two megatons, But if it was a loose conglomeration of stones and gravel, as several experts believe may the case, it might easily disintegrate as it skims into the atmosphere.
Unfortunately, not enough is known about the asteroid. 'That is our problem - we don't know what it is," said Donald Yeomans, manager of Nasa's Near Earth Object Program office at JPL. 'All we know is how bright it appears to be, and so we have to guess to come up with a diameter.'
It is thought that there are more than 100,000 asteroids of the estimated size of SG344 scattered around the solar system. A few approach the Earth, and on average one strikes our planet every 100 years, the last resulting in the 20-megaton blast that levelled 700 square miles of forests of central Siberia in 1908, the Tunguska explosion. A blast like that in a heavily developed area - California or Japan - could result in millions of deaths.
In the next few months, astronomers will try to gather more data about SG344 in a bid to learn more about its orbit and to determine more accurately its chances of hitting earth - though they have had little success so far.
Future observations may yield better data, however, allowing scientists to predict more accurately its chances of striking earth.
But the object is slowly moving away from us, which means astronomers have only a short time to gather more data and so refine their orbital calculations. If they fail, they will have to wait until 2028, when SG344 comes into range again.
In such circumstances, earth will have very little time to act if it turns out that the asteroid is doomed to collide with us.
"My own feeling is that an object this small would not be worth a great effort to deflect it, even if it is on course toward Earth,' added David Morrison.
'I don't see an argument for any sort of crash effort.'
It remains to be seen if people agree in 2030.
...it happened before: our planet is struck regularly by objects crashing down on us from outer space. The best recorded of these events occurred in 1908 when a small asteroid, about 300 feet in diameter, exploded high above the Tunguska River valley in Siberia, producing a brilliant blue fireball that knocked people off their feet 40 miles away, and flattened millions of trees.
