It's called Apophis. It's 390m wide. And it could hit Earth in 31 years

[IndianaGreen]

It's called Apophis. It's 390m wide. And it could hit Earth in 31 years time

· Scientists call for plans to change asteroid's path
· Developing technology could take decades

Alok Jha
Wednesday December 7, 2005
The Guardian

In Egyptian myth, Apophis was the ancient spirit of evil and destruction, a demon that was determined to plunge the world into eternal darkness.

A fitting name, astronomers reasoned, for a menace now hurtling towards Earth from outerspace. Scientists are monitoring the progress of a 390-metre wide asteroid discovered last year that is potentially on a collision course with the planet, and are imploring governments to decide on a strategy for dealing with it.

Nasa has estimated that an impact from Apophis, which has an outside chance of hitting the Earth in 2036, would release more than 100,000 times the energy released in the nuclear blast over Hiroshima. Thousands of square kilometres would be directly affected by the blast but the whole of the Earth would see the effects of the dust released into the atmosphere.

And, scientists insist, there is actually very little time left to decide. At a recent meeting of experts in near-Earth objects (NEOs) in London, scientists said it could take decades to design, test and build the required technology to deflect the asteroid. Monica Grady, an expert in meteorites at the Open University, said: "It's a question of when, not if, a near Earth object collides with Earth. Many of the smaller objects break up when they reach the Earth's atmosphere and have no impact. However, a NEO larger than 1km will collide with Earth every few hundred thousand years and a NEO larger than 6km, which could cause mass extinction, will collide with Earth every hundred million years. We are overdue for a big one."

Apophis had been intermittently tracked since its discovery in June last year but, in December, it started causing serious concern. Projecting the orbit of the asteroid into the future, astronomers had calculated that the odds of it hitting the Earth in 2029 were alarming. As more observations came in, the odds got higher.

http://www.guardian.co.uk/space/article/0,14493,1660485,00.html

Previous DU threads on the topic of Apophis:

Scientists to place radio transmitter on giant asteroid which endangers li

Topic started by lovuian on Aug-24-05 09:49 PM

http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=228&topic_id=11946

Astronomers Gear Up for Historic Asteroid Pass in 2029

Topic started by emad on Aug-24-05 10:14 AM

http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=228&topic_id=11885

Will Asteroid 99942 Apophis hit Earth?

Topic started by HeeBGBz on Jul-26-05 03:42 PM

http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=228&topic_id=9490

[Tom Joad]

1. I want to know exactly when. I will skip doing my laundry that week. eom

[IndianaGreen]

4. I will probably go to the local pub and watch the TV coverage

When it comes to NEOs, there is a lack of telescopes to watch the Southern Hemisphere. The amount of money that it will take to watch the skies for threatening NEOs is a mere pittance compared to the money we spent building nuclear subs that will do nothing to protect us from harm.

[rockymountaindem]

2. Don't they find these things all the time

and then re-do their math and find out it's not going to hit us after all?

[Journeyman]

8. Yes. But those re-calculations usually occur. . .

just after Congressional appropriations are apportioned to those agencies that inspire the most irrational fear. . .

[Dead_Parrot]

11. So far... ;-)

If you look at the orbit of Apophis, it crosses ours on a regular basis. If it's been there since the early days of the solar system, Gott's rule suggests it will continue to scare us on a reqular basis but never actually hit us.

It's worth bearing in mind that droping an asteroid into the solar system and hitting the Earth is roughly equivalent to playing golf on a 50 mile long fairway and getting a hole-in-one. Earth isn't really that big.

[rman]

13. They don't so much re-do their math

as they do use the latest update of the data in their calculations.

The more data points they have, the longer the stretch of the orbit they cover, the closer by it gets - the more accurate the prediction of its location in the future.

If the chance of impact increases as they update the calculations, it's not immediate reason for optimism.

[unpossibles]

3. hmm

scary thought.

[shenmue]

5. Oops

We're all gonna die.

:scared:

:cry:

[politicat]

6. And after it near misses, but goes hurtling between the moon and Earth,

the moon breaks apart and magic is released upon the land. Sorcerers rise and the mightiest of warriors will battle the forces of darkness to preserve the forces of good....

Too many cartoons as a child....

[SteppingRazor]

9. Ariel! Ookla! RIDE!!!! n/t

[trotsky]

24. Close but not quite.

It's magick with a K that gets released, remember?

[democracyindanger]

7. Awesome. I'll probably be dead.

Or close to it. I'm gonna cash my 401k in.

[Boomer]

10. I may still be alive by then, but...

...I'll be in my early 80's.

Old enough to be ready to go, but not so old that I can't enjoy the show. Gotta admit, the Apocalypse will be one helluva headliner.

[Emperor_Norton_II]

12. Dude, it's 390m

It's not the end of the world unless you live within fifty miles of the impact point. The K-T comet, this ain't.

[rman]

14. effects of 390m dense stone meteorite impact:

Impact Effects
Robert Marcus, H. Jay Melosh, and Gareth Collins
http://www.lpl.arizona.edu/impacteffects/

I choose impact in water of a dense rock meteorite half-way around the earth from my location.

The short version: you're right, the impact will not cause the end of the world.

Among the notable effects is a size 6.9 earth quake that lasts for more then an hour. The sound of the impact can be heard half-way around the earth. An impact of this size happens every 55,000 years.

---

Impact Effects

Please note: the results below are estimates based on current (limited) understanding of the impact process and come with large uncertainties; they should be used with caution, particularly in the case of peculiar input parameters. All values are given to three significant figures but this does not reflect the precision of the estimate. For more information about the uncertainty associated with our calculations and a full discussion of this program, please refer to this article

Inputs:
Distance from Impact: 20000.00 km = 12420.00 miles
Projectile Diameter: 390.00 m = 1279.20 ft = 0.24 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 45 degrees
Target Density: 1000 kg/m3
Target Type: Ice (/water)

<snip>

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

<snip>

Seismic Effects:
The major seismic shaking will arrive at approximately 4000 seconds.
Richter Scale Magnitude: 6.9
Mercalli Scale Intensity at a distance of 20000 km:
Nothing would be felt. However, seismic equipment may still detect the shaking.


Ejecta:
Little rocky ejecta reaches this site; fallout is dominated by condensed vapor from the projectile.


Air Blast:
The air blast will arrive at approximately 60600 seconds.
Peak Overpressure: 39.4 Pa = 0.000394 bars = 0.00559 psi
Max wind velocity: 0.0928 m/s = 0.208 mph
Sound Intensity: 32 dB (Easily Heard)

[Emperor_Norton_II]

15. I think you read the quake effect wrong

The seismic wave doesn't last an hour, it takes 4000 seconds to travel all the way from the impact site to your location on the other side of the planet. The actual seismic event is over in a few seconds, like hitting a gong.

[rman]

20. you're correct; i misread

[IndianaGreen]

18. And if it hits the ocean...

what size tsunami can we expect?

[rman]

19. the simulation doesn't take tsunami into account

but it's expected to be quite large

[muriel_volestrangler]

16. Estimated chance of collision: 1 in 5,500

Alan Fitzsimmons, an astronomer from Queen's University Belfast, said: "When it does pass close to us on April 13 2029, the Earth will deflect it and change its orbit. There's a small possibility that if it passes through a particular point in space, the so-called keyhole, ... the Earth's gravity will change things so that when it comes back around again in 2036, it will collide with us." The chance of Apophis passing through the keyhole, a 600-metre patch of space, is 1 in 5,500 based on current information.

[whyverne]

17. So the odds are better than:

getting struck by lightning
getting attacked by a shark
being blown up by terrorists
being in a plane crash
getting bit by a snake
getting killed in a car crash
having your house burn down
being murdered
having your kid abducted
etc.
Optimistic bunch here! I guess they don't worry much about anything.

[oneighty]

21. Silly

Apophis has passed on.

I watched it happen recently on SG1.

180

[Phoonzang]

22. Dammit, I wanted to make the SG-1 Joke! n/t

[oneighty]

23. I saved you

the embarrassment.

Science forum does not take kindly to silly jokes.

There are many well informed people on this forum.

Welcome to DU.

180

[enlightenment]

25. I also considered making the connection to SG-1,

since I'm a historian, not a scientist -- but my brother is a science guy, and as nice as he is, he's seriously humor challenged. Discretion being the better part of valor, I refrained.

Glad someone did it!