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Mars could get hit by giant comet next year!

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#26 Centaur

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Posted 28 February 2013 - 04:05 PM

Mars should be far enough from the sun in October 2014 to be in a dark sky for somebody on the this planet to make observations. See Curt's charts further back in this thread. The solar elongation is above 60 degrees I think - could be higher


Sixty is very close, Tonk; actually about 58.8°. So you are quite right that it will be in the nighttime sky for some observers. And indeed as you implied earlier the error range would make any hits on the near or far sides equally likely.

I’ve been in contact with Aldo Vitagliano, the creator of the Solex astronomical numerical integration program. He developed 50,000 clones of the comet that fit within the possible error range of the still quite preliminary data. After running them through Solex he got 6 hits or 0.0012%. So a collision appears extremely unlikely, though still possible. Aldo hopes to know more tomorrow. If so, he’ll send me a file with a thousand clones including a few impactors to input into my copy of Solex. That may cause me to fine tune my chart: www.CurtRenz.com/comets

#27 RedLionNJ

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Posted 28 February 2013 - 04:44 PM

I forgot to point out that even though Elenin estimates the comet diameter as 50 km, others (Bortle) recon that absolute brighness equates to a 5 km object. This is fair as a 50 km object is represented by Hale-Bop. Siding Springs doesn't look like its a Hale-Bop class comet.

So thats a 5 km object with a > 600,000 km uncertainty aiming at a 6,800 km cross section ....


Thank you for somebody else speaking out with rationale and sensibility. When I first heard of this close pass to Mars, I immediately downloaded all the observations from the MPC and stuffed them into Bill Grey's find_orb (spectacularly powerful piece of software that's often overlooked) - estimated closest proximity to Mars was in the order of half a million kilometers with the uncertainty being about 350,000km. To me, that strongly implies "no collision possible". If this was Earth instead of Mars, it would be a zero on the Torino Scale...

Grant

#28 AlaskaIsCold

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Posted 28 February 2013 - 04:58 PM

So just a question.
With the comet most likely just doing a very VERY close flyby of mars. Have they calculated what the flyby would do to its orbit?

#29 Centaur

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Posted 28 February 2013 - 05:08 PM

With the comet most likely just doing a very VERY close flyby of mars. Have they calculated what the flyby would do to its orbit?


Well each of Aldo's 50,000 clones would be affected in a manner that causes it's orbit too to be altered differently from all of the others (not counting the six that hit, of course).

#30 AlaskaIsCold

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Posted 28 February 2013 - 11:18 PM

Huh...
How did he run the simulation ?

#31 Centaur

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Posted 01 March 2013 - 01:18 AM

How did he run the simulation ?


Aldo ran it on the Solex astronomical numerical integration program that he created. Numerical integration avoids Kepler's difficulties with multi-body scenarios. It repeatedly utilizes Newton's two more basic force formulae for motion and gravitation. You can download a free copy of Solex at: http://main.chemistr...alvitagl/solex/

However, your copy will not have data for recently discovered comet C/2013 A1. Aldo once told me that he obtains initial positions and velocities for minor bodies from NEODyS. I expect him to soon e-mail me some preliminary data for C/2013 A1.

When data are still uncertain, Aldo generates many clones with initial conditions slightly different than the nominal solution, but within the range of possible error. For the recent flyby of asteroid 2012 DA14 he generated only 50 clones, but for this comet that is still 20 months away he generated 50,000.

If you read any of Jean Meeus' books, especially in his "Mathematical Astronomy Morsels" series, you will find Jean describing some of Aldo's simulations involving many clones.

BTW, Aldo Vitagliano is an Italian chemistry professor who happens to be extremely expert in celestial mechanics. He is a member of this message board who posts under his real name, but participates infrequently.

#32 AlaskaIsCold

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Posted 01 March 2013 - 02:05 AM

Wow... That is so much more complicated than I can understand.
haha.
It will take me a few days to try and wrap my head around Solex.

PS: Your maps are awesome.

#33 Centaur

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Posted 01 March 2013 - 02:29 AM

Wow... That is so much more complicated than I can understand.
haha.
It will take me a few days to try and wrap my head around Solex.

PS: Your maps are awesome.


Thanks for your kind words, Christopher. Be sure to read the Solex user manual. It can be found in the DOCS folder within the Solex110 folder as Word file SOLEX110. If that doesn't help, Aldo's e-mail address is near the top of the manual, and at the Solex website where he says inquiries are appreciated.

Numerical integration is far more accurate than any other method for predicting the positions of solar system bodies. Sorry, Kepler. For bodies with accurately known starting conditions, their past and future positions can be confidently calculated for hundreds of thousands of years, unless they pass too closely to each other. This could not be done until high-speed computers were invented to perform the chore of repeatedly calculating new positions across short time intervals.

#34 Ron359

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Posted 01 March 2013 - 12:42 PM

I forgot to point out that even though Elenin estimates the comet diameter as 50 km, others (Bortle) recon that absolute brighness equates to a 5 km object. This is fair as a 50 km object is represented by Hale-Bop. Siding Springs doesn't look like its a Hale-Bop class comet.

So thats a 5 km object with a > 600,000 km uncertainty aiming at a 6,800 km cross section ....


Thank you for somebody else speaking out with rationale and sensibility. When I first heard of this close pass to Mars, I immediately downloaded all the observations from the MPC and stuffed them into Bill Grey's find_orb (spectacularly powerful piece of software that's often overlooked) - estimated closest proximity to Mars was in the order of half a million kilometers with the uncertainty being about 350,000km. To me, that strongly implies "no collision possible". If this was Earth instead of Mars, it would be a zero on the Torino Scale...

Grant


I agree, it appears Phil Plait is promoting "Bad Astronomy" now?! I'm disappointed in his falling into hyping this stuff.

IF its as close as 23,000 miles to Mars, as his speculated distance is, after better orbital data, of a 4,200 mile di. planet thats over 5.5 Mars diameters away, like missing Earth at 125,000 miles or half the distance to our Moon. We'd love to see a comet in our sky that close. But, "Close but no cigar" is what I'd say.

This impact possibility was started by a guy who doesn't know how JPL ephemeris generator works, and was debunked a month ago. Better orbital data since then hasn't raised the probability much.

http://astroblogger....ng-spring-hi...

Ron

#35 Centaur

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Posted 02 March 2013 - 04:22 PM

Due to the latest (March 1) observational data for comet C/2013 A1 (Siding Spring), today Aldo Vitagliano provided me with initial conditions for 2000 clones to be entered into his Solex numerical integrator. The clones represent deviations from the nominal solution within the range of reasonable error. He has upgraded the probability of collision with Mars to 1 / 333 from his previous figure of 1 / 8333.

In response, I have updated my diagram illustrating an “overhead” (north of ecliptic) view of the encounter with output from what Aldo considers to be the nominal solution. Under the nominal solution during closest approach to Mars the comet’s heliocentric eccentricity switches from hyperbolic to elliptical. The closest approach between the centers of Mars and the comet utilizing the nominal solution is 50,586 km (81,410 mi) on 2014 OCT 19 at 19:21:24 UT. My diagram can be found at: www.CurtRenz.com/comets

#36 Centaur

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Posted 04 March 2013 - 07:32 PM

I’ve added an equatorial finder chart. It may give you a better idea regarding the relative movements of Mars and the comet: www.CurtRenz.com/comets

#37 Tonk

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Posted 04 March 2013 - 08:42 PM

Thats very useful Curt.

It also shows me this event is going to be very low and close to the horizon in the worse part of my nearest city LP dome :( - oh well!

#38 Centaur

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Posted 04 March 2013 - 09:28 PM

Thats very useful Curt.

It also shows me this event is going to be very low and close to the horizon in the worse part of my nearest city LP dome :( - oh well!


Tonk, I'll see what I can do about that. ;)

#39 Darren Drake

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Posted 06 March 2013 - 03:54 PM

Latest update: The NEO Program Office has estimated the approach could be as close as 31,000 miles. Todays Spaceweather has a link also.
http://www.nasa.gov/...et20130305.html

#40 Centaur

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Posted 06 March 2013 - 04:47 PM

The closest approach between the centers of Mars and the comet utilizing the nominal solution is 50,586 km (81,410 mi) on 2014 OCT 19 at 19:21:24 UT.


It's too late to edit my March 2nd post. I incorrectly multiplied instead of divided when converting kilometers to miles. It should have read 31,433 mi. Sorry. When are we ever going to stop using those cumbersome English measurement units?

#41 GlennLeDrew

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Posted 07 March 2013 - 12:08 AM

The process of running a series of predictions covering the range of known errors is called a Monte Carlo simulation.

If nothing else, this event will provide a unique opportunity for the direct comparison of the size of a planet and a comet coma/tail.

#42 azure1961p

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Posted 07 March 2013 - 08:03 AM

It would be interesting if this pass by broke up the comet like Jupiter did to Shoemaker-Levy9 and some impacted on the surface. I know it hasn't hit the gravitational muscle of Jove but if the thing gets close enough might it not get unstable?

Just a guess here.

Pete






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