Talk:2007 WD5

feet VS metres

i think SI units should have priority than the imperial ones (Nabukhadnezar (talk) 17:48, 21 December 2007 (UTC))

Agreed, changed. Tpheiska (talk) —Preceding comment was added at 21:59, 21 December 2007 (UTC)

Horizons

1. Go to http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2007WD5
2. Make sure "Ephemeris Type" is set to Observer.
3. Click "Observer Location" and change to @mars (Mars (body center) [500@499]).
4. Click "Time Span" and set to 2008-01-29 to 2008-01-31 STEP 1 minute.
5. (if you want) Table Settings: remove 1,9,23,24. Make sure 20 (Obsrv range & rng rate) is checked.
6. Generate away.

Delta is the distance (in AU) from Mars. Deldot is the change in direction in KM/Sec. The closest distance is currently "2008-Jan-30 09:10" at .0003AU. But do keep in mind that the orbit of this object is not yet well determined.
-- Kheider (talk) 17:59, 21 December 2007 (UTC)

New orbital elements have been released! The old data used 25 observations over 29 days, while the new data uses 28 observations over 41 days. The closest distance is now "2008-Jan-30 11:45" at 0.00014AU (~21,000km). This is half the distance of the original estimate. But as the orbit gets better determined any distance greater than about 4000km should be a miss. -- Kheider (talk) 03:46, 24 December 2007 (UTC)

New data is coming in. The Magdalena Ridge Observatory acquired 4 new images on 12/29 and 12/31. There are now 32 observations over a data-arc span of 53 days (2007-11-08 to 2007-12-31). It now looks like the asteroid will miss Mars by ~35,000km. More details to come. Hey, the odds were only 4%! :-) -- Kheider (talk) 18:29, 1 January 2008 (UTC)

Let's wait for an announcement by NASA or other WP:RS and update this article, then. Thanks for keeping an eye on this. Awolf002 (talk) 21:38, 1 January 2008 (UTC)

I agree with waiting for Horizons or NASA. The new observations moving the asteroid from 21,000km from Mars to a suggested 35,0000km from Mars will not help encourage an impact. But I have no idea how the preliminary data affects the (Dec 28th) uncertainty region of 400,000km. I assume (hope?) the uncertainty region still overlaps Mars. Horizons was down for almost 12 hours. I was hoping that they would put in the new orbital elements. I assume they want to double check all the data. -- Kheider (talk) 22:11, 1 January 2008 (UTC)

I think the probability will go up a little with that data, because 35,000km is well within uncertainty region and that region won't sink very quickly. If I set new uncertainty region as 200,000km and regard it as 3 STD, 35,000km is still within 0.6 STD, which affects prob but not too much. So the probability at the moment should be like 5-6%. Ainu7 (talk) 10:01, 2 January 2008 (UTC)

Diagram requested

Could someone create a simple diagram comparing both the size of 2007 WDF and the expected crater on Mars with known earth objects? An illustration of the orbit would help, too. Also, more content about Mars-crosser asteroids would be great. —Viriditas | Talk 03:29, 22 December 2007 (UTC)

two questions

What date will it be visible again (move out from behind the moon)?

And, if it does hit mars, will that part of mars be facing the earth, and the impact thus be visible from earth? Ariel. (talk) 08:28, 27 December 2007 (UTC)

Since this asteroid is so faint (400,000x fainter than naked eye visibility) the Full Moon has been near the same part of the sky as the asteroid drowning out its dim light. They should be able to reacquire it in the next few days. The updated orbital elements came from Precovery images from the Apache Point-Sloan Digital Sky Survey dating back to 2007-11-08. The impact flash would be brief and might only be visible to large telescopes. The event would really only be observable with the Hubble and probes in orbit around (or on) Mars. -- Kheider (talk) 15:06, 27 December 2007 (UTC)

Thanks for the answer. I was actually thinking of hubble when I asked, I know the probes in orbit can photo the crater, but I was wondering if it would be possible to watch it live, as it impacted. Hmm, can they move the probes in orbit if they wanted to? To watch it live if they happened to be on the wrong side? Probably not, I guess, so I really hope hubble can watch it. Ariel. (talk) 20:51, 27 December 2007 (UTC)

I think the question should be is if the impact will be on the night or day side. While I realize Mars rotates, it would be a shame for it to happen at night, but I can only imagine geologists on earth will be going insane watching the impacts for study. --Hourick (talk) 21:55, 27 December 2007 (UTC)

reqimage

A photo of the asteroid would be nice (even if its a point of light)

A diagram of the orbit would be nice

70.55.86.184 (talk) 08:04, 29 December 2007 (UTC)

Discovery images can be found at the University of Arizona/ Catalina Sky Survey. I do not known about the copyright status. An orbit diagram can be generated with "External Links: Orbital simulation". I have seen these used on wikipedia before. -- Kheider (talk) 16:34, 29 December 2007 (UTC)

2084

Perhaps the tool isn't the most accurate (especially considering how little we know about what's going to happen only a month from now), but is there anything to be said about the proximity of Earth and the asteroid on 12 October 2084? See this tool at JPL. --Bossi (talk • gallery • contrib) 23:23, 29 December 2007 (UTC)

Until the orbit is better refined with an observation arc of more than 41 days, it probably is not reliable to run predictions beyond the most recent encounters. Any error margin will be greatly amplified by a close approach to a planet. The Orbital Simulation applet is driven by two-body motion approximation (i.e., no perturbing planets are included) and can not really be used for long term orbit extrapolations. Horizons ephemeris handles planetary perturbations and osculating orbital elements. -- Kheider (talk) 01:54, 1 January 2008 (UTC)

10-4, just wanted to make sure we weren't potentially missing anything interesting. Thanks! --Bossi (talk • gallery • contrib) 03:39, 2 January 2008 (UTC)

Moon

Shouldn't it be noted that it could become a moon of Mars if it goes really close to Mars but doesn't hit. (I don't know.) User:Coby2 —Preceding unsigned comment added by 75.164.224.204 (talk) 23:49, 31 December 2007 (UTC)

It will not become a new moon because it is coming in at 13km/sec which is almost 3x faster than Mars escape velocity of 5km/sec. -- Kheider (talk) 01:54, 1 January 2008 (UTC)

What if the asteroid lost its velocity while close to Mars? Say, Mars' atmosphere slowed down the asteroid, but the asteroid didn't impact the planet itself. It just flew across the planetary sky then orbited around Mars? I know this is extremely unlikely. But there is a chance it could happen. But there's also a chance that the asteroid can slingshot away from our solar system. 70.157.116.27 (talk) 06:57, 1 January 2008 (UTC)

Mars upper atmosphere is very thin and would not realistically slowdown the asteroid by a factor of close to 3, allowing it to be captured. (Keep in mind that in the upper atmosphere the escape velocity from Mars will be less than 5km/sec.) Mars can not accelerate and sling shot the asteroid out of the solar system because Mars escape velocity is less than the Suns escape velocity at Mars orbit. Only the Gas Giants have enough gravity (relative to the Sun) to accelerate and slingshot asteroids completely out of the solar system. -- Kheider (talk) 11:51, 1 January 2008 (UTC)

Image of WD5

If someone will contact me by email at ebeshore@lpl.arizona.edu, I can supply you with JPEGs of the discovery images. Ed Beshore, Catalina Sky Survey 70.56.224.130 (talk) 20:49, 2 January 2008 (UTC)