Lara Croft Online
07-29-2002, 05:35 AM
Asteroid experts: Study will prove threat is 'zero'
Friday, July 26, 2002
By BOB GROVES
Staff Writer
The already minute odds of two recently-discovered asteroids hitting the Earth within the next couple of decades could be reduced even further as more is learned about their orbits, astronomers said Thursday.
As it is, the fact that not one, but two large, Earth-threatening asteroids appeared this week within days of each other is "highly unusual," said Wayne T. Hally, a meteor expert in High Ridge.
"For both of these to hit the news at the same time is really unheard of," said Hally, meteor research coordinator for the New Jersey Astronomical Association.
Astronomers on Wednesday announced that a 1.2 mile-wide asteroid, called 2002 NT7, has a one-in-250,000 chance of colliding with Earth on Feb. 1, 2019.
That news came two days after reports that a 0.3 mile-wide asteroid, designated 2002 NY40, would pass within 330,000 miles - just beyond the Moon's orbit - next month. It has a one-in-500,000 chance of striking the Earth on Aug. 18, 2022.
Both asteroids were discovered this month by the Lincoln Laboratories Near-Earth Research (LINEAR) project in New Mexico: The one designated 2002 NY40 was spotted July 14, and 2002 NT7 on July 9. The latter's closest approach to Earth in the near future, also in mid-August, will be 50 million miles.
Asteroids are cratered mini-planets made of rock and iron. Most orbit harmlessly around the Sun in a belt between Mars and Jupiter. However, some asteroids, like these two, follow more eccentric orbits that in some cases cross paths with Earth's orbit.
Now that astronomers know these two asteroids are out there, they will be closely studying their orbits and recalculating what the odds are that they might hit Earth, Hally said.
Those odds "most likely will be reduced, once more is learned about them. We don't have very precise orbits yet, because these asteroids were just discovered," Hally said.
"There's a lot of error now. But once the orbits are observed more closely, the odds [of collision with Earth] will probably go further and further down. Because the longer you observe it, the better you can say it's on this path, not the other."
Either asteroid could cause immense damage in a collision, astronomers say. The one called 2002 NY40 could have the impact of 100,000 megatons of TNT, and 2002 NT7 could be 10times larger: 1 million megatons of TNT. An asteroid believed to have destroyed hundreds of acres of trees when it exploded above Tunguska, Siberia, in 1908 was estimated at about 40 megatons.
Bruce Draine, an astrophysicist at Princeton University, also believes the chances of a catastrophe will become more remote as scientists learn more.
"Those odds reflect today's level of knowledge," Draine said Thursday. "It's highly likely, as the orbits are improved, that one would reach the point where the probabilities of these two asteroids hitting the Earth would be reduced essentially to zero," he said.
"But we don't know that, so one has to keep looking," Draine said.
Source : NorthJersey.com (http://www.bergen.com/page.php?level_3_id=7&page=4419010)
Friday, July 26, 2002
By BOB GROVES
Staff Writer
The already minute odds of two recently-discovered asteroids hitting the Earth within the next couple of decades could be reduced even further as more is learned about their orbits, astronomers said Thursday.
As it is, the fact that not one, but two large, Earth-threatening asteroids appeared this week within days of each other is "highly unusual," said Wayne T. Hally, a meteor expert in High Ridge.
"For both of these to hit the news at the same time is really unheard of," said Hally, meteor research coordinator for the New Jersey Astronomical Association.
Astronomers on Wednesday announced that a 1.2 mile-wide asteroid, called 2002 NT7, has a one-in-250,000 chance of colliding with Earth on Feb. 1, 2019.
That news came two days after reports that a 0.3 mile-wide asteroid, designated 2002 NY40, would pass within 330,000 miles - just beyond the Moon's orbit - next month. It has a one-in-500,000 chance of striking the Earth on Aug. 18, 2022.
Both asteroids were discovered this month by the Lincoln Laboratories Near-Earth Research (LINEAR) project in New Mexico: The one designated 2002 NY40 was spotted July 14, and 2002 NT7 on July 9. The latter's closest approach to Earth in the near future, also in mid-August, will be 50 million miles.
Asteroids are cratered mini-planets made of rock and iron. Most orbit harmlessly around the Sun in a belt between Mars and Jupiter. However, some asteroids, like these two, follow more eccentric orbits that in some cases cross paths with Earth's orbit.
Now that astronomers know these two asteroids are out there, they will be closely studying their orbits and recalculating what the odds are that they might hit Earth, Hally said.
Those odds "most likely will be reduced, once more is learned about them. We don't have very precise orbits yet, because these asteroids were just discovered," Hally said.
"There's a lot of error now. But once the orbits are observed more closely, the odds [of collision with Earth] will probably go further and further down. Because the longer you observe it, the better you can say it's on this path, not the other."
Either asteroid could cause immense damage in a collision, astronomers say. The one called 2002 NY40 could have the impact of 100,000 megatons of TNT, and 2002 NT7 could be 10times larger: 1 million megatons of TNT. An asteroid believed to have destroyed hundreds of acres of trees when it exploded above Tunguska, Siberia, in 1908 was estimated at about 40 megatons.
Bruce Draine, an astrophysicist at Princeton University, also believes the chances of a catastrophe will become more remote as scientists learn more.
"Those odds reflect today's level of knowledge," Draine said Thursday. "It's highly likely, as the orbits are improved, that one would reach the point where the probabilities of these two asteroids hitting the Earth would be reduced essentially to zero," he said.
"But we don't know that, so one has to keep looking," Draine said.
Source : NorthJersey.com (http://www.bergen.com/page.php?level_3_id=7&page=4419010)