Whew! you had me going there spewey, that's an asteroid and not a comet. Man-o-man if only that were a real comet though! Even if it passed by as close as the moon it would be the show stopper of the century. The tail would stretch from horizon to horizon and fill the sky even during the day.

But I'd say that 1600 megatons would give you quite a shock wave rattle being 5 hours away (250 miles?). Lots of ashy fallout (non-radioactive of course) if the winds are blowing your way, but any blast damage at your home should be minimal IMHO. vgkg

Oh, that's better. I'm much less troubled that it's an asteroid about to hit than a comet. Sorry if I concerned anyone. Being hit by an asteroid shouldn't be a very big deal.

LOL, good one spewey!....
Although you are right about comets being much worst, even those with the same mass as an asteroid. Comets in general are traveling at a much higher impact velocity compared to most roids.

Spewey, Decatur is not far from downtown Atlanta and my part-time home. The main CDC Offices (Centers for Disease Control) are in Decatur. Hopefully, I'll be retired by then and out of the way up in the mountains of NW Georgia - unless the Social Security crisis or the fix (either one) require that I keep working into my mid-70's.

KT,

They same the comet--sorry, asteroid--is 1,321' long, so hopefully your home is further from Decatur than that. Good luck and we'll be pulling for you.

Perhaps the greater concern is what GW will be doing tomorrow here on Earth. Ask again about the comet come the end of 2028, if we're both still around.

till then good fortunes....

I think GardenWeb will be around tomorrow. In fact, I am so confident in GW that I will be renewing my membership that is due to expire next month. Thanks for the reminder.

I have been to 3 EOW (end of the world parties) already, and was looking forward to going to another one. I guess we will have to reschedule.

Actually all any us needed was a reason to have a party: hurricanes, earthquakes, sunny days, or Alfred Hitchcock's birthday (Aug 13th if you are interested.) Didn't matter :)

Anyway, I am about 2500 miles from Decatur anyway. To quote Alfred E Neuman, "What me, worry?"

It may not hit the Earth but man it doesn't get much closer than this...

Closest Flyby of Large Asteroid to be Naked-Eye Visible
By Robert Roy Britt
Senior Science Writer
posted: 04 February 2005
01:31 pm ET

An asteroid expected to fly past Earth in 2029 will be visible to the naked eye, scientists projected Thursday.

It's a once-in-a-millennium event. And you may want to buy plane tickets now, as the flyby will be visible only from Europe, Africa and western Asia.

There has been no event like this in modern history. Some people have seen dramatic fireballs created by small space rocks blazing through Earth's atmosphere. And two house-sized asteroids have made closer passes. But they were not visible without telescopes.

The 2029 event will be the closest brush by a good-sized asteroid known to occur. The rock will pass Earth inside the orbits of some satellites. No other asteroid has ever been clearly visible to the unaided eye.

The asteroid is roughly estimated to be a little more than 1,000 feet (320 meters) wide.

It won't hit

The rock, catalogued as 2004 MN4, was discovered last June. It was seen again in December, and for a time scientists said it had the highest odds of hitting Earth ever given to a space rock. Subsequent observations refined the future path and eliminated those odds for the 2029 flyby. It won't hit the Moon, either.

This week, NASA scientists used new observations from the Arecibo Observatory to further pin down the track of 2004 MN4.

On April 13, 2029, it will be about 22,600 miles (36,350 kilometers) from Earth's center. That is just below the altitude of geosynchronous satellites, which hover in fixed perches above the planet to communicate with and collect data on half the globe at all times.

Of the ten known closest asteroid flybys, 2004 MN4 is by far the largest object, said Steve Chesley of NASA's Jet Propulsion Laboratory. Only two have come closer, and they were only tens of yards (meters) wide.

"All of the others in the top ten were discovered during the close approach, whereas for 2004 MN4 the close approach is predicted well in advance," Chesley said in a telephone interview.

Last fall, an even larger asteroid made a notable flyby. That rock, called Toutatis, is about 2.9 miles long and 1.5 miles wide (4.6 by 2.4 kilometers). Its closest approach, widely photographed, was about four times the distance to the Moon. It was not visible to the naked eye.

What to expect

The asteroid 2004 MN4 is expected to shine like a fast-moving star at magnitude 3.3, Chesley said. That would be easily visible under dark skies without the help of binoculars or telescopes.

On this astronomers' magnitude scale, smaller numbers represent brighter objects. The brightest stars and planets have negative magnitudes. The dimmest stars visible under perfect sky conditions away from city lights are about magnitude 6.5. Urban residents may need to get out of town to see the rare event.

Chesley said the exact proximity of the object could cause its brightness to vary, but probably only by a few tenths of a magnitude.

The asteroid will pass through the constellation of Cancer. Observers with clear skies in Europe, Africa and parts of Asia will be able to see a star-like point of light.

"Whether you could see it from the center of London is another matter," said Alan Harris of the Space Science Institute.

Harris notes that asteroid Vesta -- 334 miles (538 kilometers) in diameter -- periodically gets as bright as magnitude 5.3, which is visible to the naked eye under very dark sky conditions. "Curiously, Vesta attains this brightness at its opposition in July, 2029, only a few months after the April 2029 apparition of MN4," Harris told SPACE.com.

With small telescopes and high-tech tracking software, the asteroid's shape could be evident.

"It will be potentially resolvable with small telescopes, but they'll have to be able to track pretty fast," Chesley said.

The rock will cover about 42 degrees of sky per hour, slower than a satellite but noticeably quick in the small field of view of a telescope.

Rare event

On average, one would expect a similarly close Earth approach by an asteroid of this size only every 1,300 years or so, Chesley and his colleagues have determined.

2004 MN4 circles the Sun, but unlike most asteroids that reside in a belt between Mars and Jupiter, the 323-day orbit of 2004 MN4 lies mostly within the orbit of Earth.

The 2029 flyby will bend the rock's path and change the circumstances of later close passes to Earth. "However, our current risk analysis for 2004 MN4 indicates that no subsequent Earth encounters in the 21st Century are of concern," according to a statement issued by Chesley and his JPL colleagues Paul Chodas, Jon Giorgini and Don Yeomans.

Additional observations in coming months and years could help eliminate the small chances of impacts in years after 2029.

Were an asteroid the size of 2004 MN4 to hit Earth, it would cause local devastation and regional damage. It would not be expected to cause any sort of global disruption, experts say.

I'm not so sure this is gonna miss. After all, it's still a long ways off.

Add up the figures in the year 2029. 2 + 0 + 2 + 9 = 13. We're doomed!

spewey, What's with the number 13? Oh, I guess it is supposed to be "unlucky".

Personally I think the odd numbers are more in sync with the heavenly....1, 3, 5, 7......

Vgkg (or anyone else!)
One line stuck out for me in your excellent article..."It won't hit the moon, either..."
Hypothetically, what if it did? What if the moon were to be destroyed? What would be the consequences for our planet? Tidal changes, for sure, but what else?

Regards,

Shax

Obsolescence of millions of songs, chants, poems and stories; however, the lamenting might be short-lived along with the rest of the planet under a deluge of moon debris.

Shax, just this past week The Science Channel aired a repeat show on "What if the Earth had no Moon". It demonstrated the consequences of a moon-less Earth. I can't seem to find the show's preview on the web now but here's a taste of what the Earth may be like without the Moon (copyrighted material below).

BTW, this little piece of space driftwood that'll pass by in 2029 wouldn't do diddily if it hit the moon. If fact, it's now excepted by most astronomers that a Mars-sized object impacted the Earth ~4 billion years ago and the moon was born of this collision. Since that time no object big enough has hit the moon to destroy her, though she's been battered and scared extensively.

Here is a link that might be useful: no moon