Talk:Near-Earth asteroid

Independent verification

Does someone have some independent verification of the June 6, 2002 impact over the Mediterranean? The only place I could find anything was at http://www.rense.com/general27/asteroidimpactsetoff.htm, which is a UFO site, so it could be completely made up and bogus. Does someone have a subscription to Aerospace Daily to double-check? -- hike395 12:02, 29 Aug 2003 (UTC)

http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/016bokal.asp - Patrick 12:19, 29 Aug 2003 (UTC)

OK, thanks! -- hike395

and http://phobos.astro.uwo.ca/~pbrown/documents/flux-final.pdf - Patrick 12:28, 29 Aug 2003 (UTC)

Wow. 26 kilotons. That's very impressive. -- hike395

Update article

Someone should update this article to mention 2004 MN4. --Sgeo^TC 21:19, Dec 27, 2004 (UTC)

Apoheles

The article states:

The Atens, which have average orbital radii closer than one astronomical unit (AU, the distance from the Earth to the Sun) and aphelia of greater than Earth's perihelion, placing them usually inside the orbit of Earth.

But Apoheles are subclasses of Atens, and do not cross Earth's orbit. Isn't the article misleading? 24.68.180.163 06:23, 21 September 2006 (UTC)[reply]

Frequency of impact

In the heading "The NEA Threat", it states that "Small collisions, equivalent to a thousand tonnes of TNT, occur a few times each month.". I have doubts about this, mostly because I have done a lot of research on this topic and found that to be inaccurate, but also because it is stated that "they estimated that similar sized asteroids come as close [42,600 km] about every two years" in the same section. So, if a small asteroid (30m) only comes within 42,600 km of the Earth every 2 years, then how is it that "small collisions, equivalent to a thousand tonnes of TNT, occur a few times each month"? Can an asteroid of fewer that 30m really cause a 1000 tonne explosion? E.boyer7 01:39, 22 October 2006 (UTC)[reply]

A 30-m object produces a MEGATONNE explosion, not a kilotonne. The kilotonne figure is for few-meter objects, which airburst in the stratosphere. This figure is very well based, from US Air Force monitoring satellites. The flux of megatonne explosions is less well constrained, based on only a few events over the last century. Michaelbusch 03:21, 22 October 2006 (UTC)[reply]

Merge with near-earth object?

Does anyone think that it would be a good idea to merge this article with near-earth object? Lunokhod 21:02, 25 January 2007 (UTC)[reply]

I weakly oppose. The definitions are somewhat different. Michaelbusch 21:28, 25 January 2007 (UTC)[reply]

I support merging, as near-earth asteroids are near-earth objects (NEO)s, and almost all near-earth objects (except spacecraft and very rarely comets) are asteroids. Furthermore, the intrinsic interest in NE objects that are not asteroids is much lower than the interest of asteroidal objects, first due to the impact hazard, second due to their scientific interest as targets for detailed astronomical and geochemical investigation, and third due to their potential value as accessible sources of useful extra-terrestrial materials. The NEO article is at this moment about 12KB long, while this article is about 22K long. The impact hazard dominates both articles. If there are to be two articles, I would suggest one devoted to the impact hazard and mitigation issues, and the other focused on the scientific questions and potential extraterrestrial resource aspects of the subject. This issue was raised two years ago, and the articles may have been different at that time, but now the overlap and redundancy seems large.

If I do not hear significant objection from other editors, I may undertake a merge and re-organization of these myself when I have time. Cheers, Wwheaton (talk) 04:13, 15 November 2008 (UTC)[reply]

I have added merge tags to both articles. I suppose the Near-Earth object article should be the survivor, with a redirect to it from Near-Earth asteroid, as asteroids are a subset of objects. I think that means the discussion link should point there, but so far I have not succeeded in making that happen; maybe someone else who sees what I have done wrong can help? Thanks Wwheaton (talk) 21:38, 28 November 2008 (UTC)[reply]

OK, I finally saw what I did wrong and have fixed the discussion links. Wwheaton (talk) 21:46, 28 November 2008 (UTC)[reply]

We have a consensus for the merge at the discussion here, 6/0. I will try to start it by the weekend. Wwheaton (talk) 22:47, 8 December 2008 (UTC)[reply]

I have added all the content of this page today to the NEOs page and propose that this page should become a mere link to the NEO site. I wote for a merge now. I propose to disable editing of this article so that new information can only be added to the merge destination, i.e. NEOs. SAE1962 (talk) 07:26, 29 December 2008 (UTC)[reply]

Are we ready to turn this page ("Near-Earth asteroid") into a redirect to Near-Earth object yet? I think all the useful content here may have been moved over there, but am not sure. Don't want to kill it off too early, but we also don't want new editors coming in and adding useful content or good corrections here, instead of at NEO. I see that there have been a few such already. Also, what becomes of the orphaned talk page? Wwheaton (talk) 23:42, 23 December 2008 (UTC)[reply]

Yes, I have moved the information and added this to the discussion page on 19th December. I vote for a redirection to the NEOs now. SAE1962 (talk) 07:26, 29 December 2008 (UTC)[reply]

OK, I am going to try the redirect. I hope this talk page is not lost, but I see nothing in the instructions to warn me off. I suppose anything I do can be fixed.... Wwheaton (talk) 17:20, 29 December 2008 (UTC)[reply]

Capture

Is there any possibility that an asteroid could, rather than passing by or colliding, be catpured by Earth's gravity and pulled into orbit? 71.203.209.0 08:34, 21 February 2007 (UTC)[reply]

Generally not. You can contort the dynamics such that this is possible, but it is rare and requires either very specific trajectories or a binary object. Michaelbusch 16:05, 21 February 2007 (UTC)[reply]

Binary object? Would this include the Earth-Moon system?Abramul 01:32, 17 March 2007 (UTC)[reply]

No. You need a binary asteroid. Michaelbusch 02:22, 17 March 2007 (UTC)[reply]

I believe it can happen with just the Earth/Moon, though it does require one of a few "very specific trajectories". The asteroid must initially enter the Earth/Moon system at very low velocity (with respect to the E/M system center of mass) and pass fairly close to the Moon, on the front side of its orbit, so that it loses energy. Then it will be bound for a while, so that further solar and lunar perturbations have a chance to move it to a stable orbit. Wwheaton (talk) 21:02, 28 November 2008 (UTC)[reply]

Tunguska Event

As I said in the main page for the Tunguska Event, I find the consensus lacking as to the cause of this event. —Preceding unsigned comment added by ChiefinspectorClousea (talk • contribs) 01:42, 15 November 2008 (UTC)[reply]

I have replied on the Tunguska Event page. What theories do you think should be given more weight, and why? Verbal chat 09:11, 15 November 2008 (UTC)[reply]