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Offline syhprum

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Will the orbit of this asteroid be disturbed
« on: 31/01/2013 15:54:01 »
On Feb 15 at 19:26 asteroid 2012DA14 is scheduled to pass the Earth at a distance of 25Km is this sufficiently close for the Earth disturb its orbit so that its next pass will be different.


 

Offline caKus

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Re: Will the orbit of this asteroid be disturbed
« Reply #1 on: 31/01/2013 16:33:46 »
If an asteroid of this size pass at 25 Km of the earth, we would better quit this planet right now.   :0
 

Offline CliffordK

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Re: Will the orbit of this asteroid be disturbed
« Reply #2 on: 31/01/2013 17:03:50 »
I think you have a unit translation problem.
Most of the sources I'm seeing indicate that in 2013, it should pass 34,000 to 36,000 km from the Earth.

As far as impact risk to Earth, the diameter is about 45 meters.  If it struck Earth, it could wipe out a city, but otherwise the impact would be generally localized, with much of the Earth being either water, or rural area.

http://en.wikipedia.org/wiki/2012_DA14
http://neo.jpl.nasa.gov/news/news174.html
http://earthsky.org/space/asteroid-2012-da14-will-pass-very-close-to-earth-in-2013

25 km would make it pass through the Exosphere, Thermosphere, Mesosphere, and down into the Stratosphere.  It would be traveling quickly with a single pass, but it undoubtedly would have weak atmospheric interactions. 

However, at about 35,000 km, the risk of unpredictable interactions with Earth and the moon are much less, unless it whacks into a satellite or large orbital object.

I'm having interpreting the 2110 data. 
http://neo.jpl.nasa.gov/risk/2012da14.html

Where is says Distance (rEarth) =  0.70

" Distance
    The minimum distance on the target plane (scaled b-plane) from the LOV to the geocenter, measured in Earth radii. For these purposes the radius of the Earth, 6420 km, includes some allowance for the thickness of the atmosphere. "


Doesn't that put it very close to Earth, if not subsurface?

 

Offline evan_au

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Re: Will the orbit of this asteroid be disturbed
« Reply #3 on: 31/01/2013 20:19:06 »
The Near-Earth Object (NEO) observation project predicts future possible impacts. Recent and future close approaches are tabulated here - there are several listed per day: http://neo.jpl.nasa.gov/ca/

The paths of these bodies are chaotic (a mathematical term), and small differences in the initial position and velocity can make a very large difference in the final path.

Astronomers take advantage of every close approach to take more accurate measures of the position, velocity and size of these NEOs, such as was done with the recent flyby of Aphophis, which resulted in its estimated mass being increased by 80%. This is used to refine the orbital predictions and potential impact damage, especially for those which rate high on the Palermo & Torino scales: http://neo.jpl.nasa.gov/risk/
 

Offline syhprum

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Re: Will the orbit of this asteroid be disturbed
« Reply #4 on: 31/01/2013 22:13:26 »
Apologies I probably misread miles for Km's nevertheless I will make a point of sitting down on the fifteenth.
 

Offline distimpson

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Re: Will the orbit of this asteroid be disturbed
« Reply #5 on: 01/02/2013 01:40:03 »
yes, the orbit will be changed by Earth's grav field, it's a pretty close approach:


http://earthsky.org/space/asteroid-2012-da14-will-pass-very-close-to-earth-in-2013

this chunker got even closer 1972:



http://apod.nasa.gov/apod/ap090302.html
 

Offline CliffordK

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Re: Will the orbit of this asteroid be disturbed
« Reply #6 on: 01/02/2013 07:13:12 »
Apologies I probably misread miles for Km's nevertheless I will make a point of sitting down on the fifteenth.
or kms for meters.

As distimpson says, one can predict the effect of gravity that the planets and moon will have on an object, all the time,  not just during close encounters.  1000 km on a pass will make some difference, but doesn't make that much of a difference to the gravitational constant.  Although, it may amplify errors out a century in advance. 

An earth grazing fireball as in the photo may also be somewhat predictable with the ultimate trajectory, but there are many additional variables including the "skipping" effect, loss of mass, asteroid composition, and loss of velocity.
 

Offline Phractality

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Re: Will the orbit of this asteroid be disturbed
« Reply #7 on: 01/02/2013 23:39:10 »
Close encounters amplify trajectory measuring errors. We might predict that the asteroid will pass 25,000 km 10 km from Earth. That 10 km on this years encounter could mean 1,000,000 km on the next encounter. So we have to wait until it has passed to find out just how much its trajectory was altered by our gravity.

P.S.: On March 12, 2005, I watched a green fireball passing so close to Earth that it actually skipped across the 8-foot swells of Pacific Ocean three times, sending up bright red flashes. Then it apparently kept on going, either suborbital or back into deep space. It was about the same angular size as the moon, and it was at least 100 km away from me at closest approach. Those estimates would make it at least ten times the diameter of one that is expected to pass us on February 15. Just a few feet lower and it could have created quite an explosion and tsunami.
Here is my illustration of what I saw.
Other observations of this fireball.
« Last Edit: 02/02/2013 00:14:20 by Phractality »
 

Offline Pmb

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Re: Will the orbit of this asteroid be disturbed
« Reply #8 on: 02/02/2013 00:38:30 »
On Feb 15 at 19:26 asteroid 2012DA14 is scheduled to pass the Earth at a distance of 25Km is this sufficiently close for the Earth disturb its orbit so that its next pass will be different.
What's the mass and size of it? If it passed that close then interacting with the atmosphere would probably detonate it with the energy comparable to thermonuclear blast. Much like the Tunguska event.  They said above, you have the distance wrong.
 

Offline Phractality

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Re: Will the orbit of this asteroid be disturbed
« Reply #9 on: 02/02/2013 06:46:00 »
On Feb 15 at 19:26 asteroid 2012DA14 is scheduled to pass the Earth at a distance of 25Km is this sufficiently close for the Earth disturb its orbit so that its next pass will be different.
What's the mass and size of it? If it passed that close then interacting with the atmosphere would probably detonate it with the energy comparable to thermonuclear blast. Much like the Tunguska event.  They said above, you have the distance wrong.
Rocky or icy objects tend to explode in the atmosphere. Metallic objects hold together until they hit something hard.

There are many eye witness reports on the fireball that I saw, but not much good data. This part of the Pacific Coast did not yet have radar, and many of the reported observations are contradictory, due to untrained observers. Naturally, I give more weight to my own observation. The object came in low from my south moving left to right just above the tree tops; it went below the tree tops to my southwest, and perhaps four seconds later, I saw a succession of three red splashes, about one second apart, reflected off the tree branches to my west. The three splashes were about equal from what I could see.

I didn't count seconds at the time, so I could be off by a factor of two or three on the timing. Initially, I thought it might have been as big as a refrigerator or a small car. I thought it might have splashed a couple miles off the coast. The importance of the event didn't sink in until days later when I realized how far away it was, and therefor how big it must have been. After looking at other witness reports, I realized it was much farther away than I had guessed. If it was the angular size of the moon and at least 100 km away, that makes it at least .87 kilometer in diameter.

99942 Aphophis is estimated to be 325 meters across, and it has been calculated that a direct hit from it would release about 510 megatons of TNT. The one I saw might have been 30 to 100 times more massive than Apophis.

My best guess is that it continued into deep space. Otherwise, it would have crashed somewhere on Earth, causing a huge explosion and/or tsunami. If scientists know what I suspect, they have kept it secret to avoid embarrassment.
 

Offline Pmb

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Re: Will the orbit of this asteroid be disturbed
« Reply #10 on: 02/02/2013 07:52:41 »
I saw a meteorite break up in the atmosphere right above my head once. It was the 70s when teenagers used to party in cementaries. I was standing there holding my beer and looked up and saw a bright green light moving not all that fast across the sky. I thought it was a plane it was moving so slow. Then it turned bright green and zipped off in another direction. I assume it was a metoerite but what else could it be. I'll never forget it though!
 

Offline CliffordK

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Re: Will the orbit of this asteroid be disturbed
« Reply #11 on: 18/02/2013 07:10:10 »
Well, 2012_DA14 passed Earth yesterday at an altitude of 34,050 km; 21,160 mi, largely overshadowed by the meteorite that actually struck Earth in Russia.

Its orbit was perturbed sufficiently by Earth that its orbital period, or "year" was reduced from 368 days (longer than Earth's year) to 317 days (shorter than Earth's year), changing it from an Apollo class to the Aten class NEO., although it remains in an Earth crossing orbit.

What caused the orbital period to decrease by 51 days?
 

Offline syhprum

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Re: Will the orbit of this asteroid be disturbed
« Reply #12 on: 18/02/2013 22:02:17 »
Thank you ClifffordK for that information I am surprised the disturbance was so large much humour seems to have been occasioned by my typo of course I meant to write 25K Km, we would certainly have felt it effects if it came in at 25Km 
 

Offline evan_au

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Re: Will the orbit of this asteroid be disturbed
« Reply #13 on: 19/02/2013 11:17:36 »
Quote
What caused the orbital period to decrease by 51 days?

This is the opposite of the "slingshot effect" used to accelerate space probes:
  • A spacecraft passes behind a planet, and some of the planet's angular momentum is transferred to the spacecraft. The spacecraft speeds up a lot, and the planet slows down by a miniscule amount.
  • 2012DA14 passed by the Earth on the side that transferred some angular momentum from the asteroid to Earth. The asteroid slowed down a bit, dropping its orbit closer in towards the Sun and reducing its orbital period (orbital period is determined by the semimajor axis of its orbit). Earth sped up by a miniscule amount.
http://en.wikipedia.org/wiki/Slingshot_effect#Explanation
 

Offline distimpson

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Re: Will the orbit of this asteroid be disturbed
« Reply #14 on: 08/03/2013 21:51:00 »
came across this site the other day, cosmic billiards

http://neo.jpl.nasa.gov/neo/groups.html


 

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Re: Will the orbit of this asteroid be disturbed
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