Posted on 12/26/2004 8:33:58 PM PST by shadowman99
Update, Dec. 25, 9:47 p.m. ET: The risk of an impact by asteroid 2004 MN4 went up slightly on Saturday, Dec. 25. It is now pegged at having a 1-in -45 chance of striking the planet on April 13, 2029. That's up from 1-in-63 late on Dec. 24, and 1-in-300 early on Dec. 24.
Astronomers still stress that it is very likely the risk will be reduced to zero with further observations. And even as it stands with present knowledge, the chances are 97.8 percent the rock will miss Earth.
Update, Dec. 24, 10:19 p.m. ET: An asteroid that has a small chance of hitting Earth in the year 2029 was upgraded to an unprecedented level of risk Friday, Dec. 24. Scientists still stress, however, that further observations will likely show the space rock won't be on a collision course with the planet.
The risk rating for asteroid 2004 MN4 was raised Friday by NASA and a separate group of researchers in Italy.
The asteroid's risk rating a possible impact scenario on April 13, 2029 has now been categorized as a 4 on the Torino Scale. The level 4 rating -- never before issued -- is reserved for "events meriting concern."
The Dec. 24 update from NASA stated:
"2004 MN4 is now being tracked very carefully by many astronomers around the world, and we continue to update our risk analysis for this object. Today's impact monitoring results indicate that the impact probability for April 13, 2029 has risen to about 1.6 percent, which for an object of this size corresponds to a rating of 4 on the ten-point Torino Scale. Nevertheless, the odds against impact are still high, about 60-to-1, meaning that there is a better than 98 percent chance that new data in the coming days, weeks, and months will rule out any possibility of impact in 2029."
With a half-dozen or so other asteroid discoveries dating back to 1997, scientists had announced long odds of an impact -- generating frightening headlines in some cases -- only to announce within hours or days that the impact chances had been reduced to zero by further observations. Experts have said repeatedly that they are concerned about alarming the public before enough data is gathered to project an asteroid's path accurately.
Asteroid 2004 MN4 is an unusual case in that follow-up observations have caused the risk assessment to climb -- from Torino level 2 to 4 -- rather than fall.
An edited version of the 2004 MN4 story originally posted on SPACE.com at 9:58 a.m. ET on Dec. 24:
Scientists said Thursday that a recently discovered asteroid has a chance of hitting Earth in the year 2029, but that further observations would likely rule out the impact scenario.
The asteroid is named 2004 MN4. It was discovered in June and spotted again this month. It is about a quarter mile (400 meters) wide. That's bigger than the space rock that carved meteor crater in Arizona, and bigger than one that exploded in the air above Siberia in 1908, flattening thousands of square miles of forest. If an asteroid the size of 2004 MN4 hit the Earth, it would do considerable localized or regional damage. It would not cause damage on a global scale. Scientists stressed, however, that the rock would likely miss the planet. A statement was released by NASA asteroid experts Don Yeomans, Steve Chesley and Paul Chodas. "The odds of impact, presently around 1-in-300, are unusual enough to merit special monitoring by astronomers, but should not be of public concern," the scientists said. "These odds are likely to change on a day-to-day basis as new data are received. In all likelihood, the possibility of impact will eventually be eliminated as the asteroid continues to be tracked by astronomers around the world." The scientists project an asteroid's future travels based on observations of its current orbit around the Sun. On computer models, the future orbits are not lines but rather windows of possibility. The orbit projections for 2004 MN4 on April 13, 2029 cover a wide swath of space that includes the location where Earth will be. Additional observations will allow refined orbit forecasts -- more like a line instead of a window. The asteroid will be easily observable in coming months, so scientists expect to figure out its path.
Most asteroids circle the Sun in a belt between Mars and Jupiter. But some get gravitationally booted toward the inner solar system. The 323-day orbit of 2004 MN4 lies mostly within the orbit of Earth. The asteroid approaches the Sun almost as close as the orbit of Venus. It crosses near the Earth's orbit twice on each of its passages about the Sun. 2004 MN4 was discovered on June 19 by Roy Tucker, David Tholen and Fabrizio Bernardi of the NASA-funded University of Hawaii Asteroid Survey. It was rediscovered on Dec. 18 from Australia by Gordon Garradd of the Siding Spring Survey. More than three dozen observations have been made, with more expected to roll in from other observatories this week.
It has been a busy stretch for asteroid scientists. Earlier this week, researchers announced that a small space rock had zoomed past Earth closer than the orbits of some satellites.
I think its doing around 15 km/sec. Thats moving pretty quick.
I was really hoping it would hit here in about 2006 --- 41:09:34N 73:45:55W
I was just thinking about that. Is there any way to know for certain that's not exactly what happened earlier today?
Any geologists here to take a stab at that?
Definitely an incredible work of science fiction. A favorite of mine from an early age :)
Not to mention the Browns and the Superbowl . . .
Ping.
I guess since the global warming thing has been pretty thoroughly debunked, the catastrophists need a new living.
We all gonna die!
My wife just old me the same thing for cookies and ice cream. Or could it be that she wants me to lose weight? Nah, I know it's the asteroid...
She's hoping if you slim down you won't be such a good target for the asteroid. That woman's a saint! :)
And it's a Friday the 13th too!
1 in 43 is still a big yawner.
Give me 1 in 10 and it will be time to sit up.
You're kidding right? A 400 meter diameter asteroid impact would make those events seem trivial by any destructive standards.
ick.....47 here.
Man, time flies.
you are kidding me....lol.
book of revelation.
a star called "wormwood" crashes into the earth in the end times and kills one third of life on the planet.
if clarke used it in one of his stories, he probably got it from there...
nothing new under the sun.
I will periodically bump this thread for the next twenty-four years.
Its a little more complicated than that, but roughly true. They have not been able to nail down some of the parameters that would allow them to get at some extremely precise orbital elements. They'll be hovering around 1:43 until they get some better sensors looking at it; right now, that represents the margin of error for the models based on a lack of important parameters e.g. the rotational period and axis relative to the sun. It isn't as though they can't produce exceedingly precise orbital predictions but that they do not trust some of the data they have so far. Some of the unofficial analyses on the same data that tries to adjust for dubious data or bad calibration and giving missing parametric data "statistically representative" values is putting impact probability at closer to 1:20. But we still need better data, which will require the asteroid to be visible in the northern hemisphere to a significant extent, something which will happen in a bit. Right now, the rock is hovering around the South Pole.
Most folks are currently giving the diameter to be a quarter-mile +/- a factor of 3 i.e. it could be 3/4 of a mile in diameter (a country killer there). The photometric calibrations have been completely hosed, leading to data that is pretty uncertain for the size calculation. Once they sort this out with a ton of high-quality measurements, I get the impression that the feeling is that this rock could actually be a bit larger than currently estimated. We'll know soon enough, but the current margin of error on the size is huge and the people examining the calibration of the current data seem to think that they may have underestimated the size. A lot of the data currently being collected is pretty amateur because the asteroid is so deep in the southern hemisphere.
A >1km diameter asteroid would be substantially more catastrophic than the current size estimate suggests.
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