Talk:Meteoroid

From Wikipedia, the free encyclopedia

	Solar System Portal This article is within the scope of the Solar System WikiProject, a collaborative effort to improve Wikipedia's coverage of the Solar System.
B	This article has been rated as B-Class on the assessment scale.

	Earth sciences Portal Meteoroid is part of WikiProject Geology, an attempt at creating a standardized, informative, comprehensive and easy-to-use geology resource. If you would like to participate, you can choose to edit this article, or visit the project page for more information.
B	This article has been rated as B-class on the quality scale.
Mid	This article has been rated as mid-importance on the importance scale.

Contents 1 Is this line correct? 2 Merge proposal 3 merger seems awkward 4 Definition of a fireball 5 head-on collisions 6 Bolide definition 7 Ionization trail 8 Beliefs 9 Mystery illness strikes after meteorite hits Peruvian village 10 Detection

[edit] Is this line correct?

hat an object must be about 50 m across before it can survive atmospheric entry[2], this means terrestrial meteo "Oddly enough, because it is thought trites never come from meteoroids."

50 meters? should this be 50 millimeters? —Preceding unsigned comment added by 68.122.74.140 (talk • contribs)

I'm not sure whether it's correct or not, but 50 mm seems a bit small to me. Mikker ^(...) 01:42, 13 December 2006 (UTC)

I think 50mm is more correct - I think I've seen the figure 2 feet depending on what it is made of. I've also heard basketball sized objects could make it to the ground.--Smkolins 17:20, 22 March 2007 (UTC)

I think that 50 meters should be correct; we need an outside source. None of us knows what's really going on. {Slash-|-Talk} 17:27, 29 April 2007 (UTC)

Here's a source: Bland and Artemieva (2006) The rate of small impacts on Earth. Meteoritics & Planetary Science 41, 607–631. Most stony meteorites come from small objects, meter-sized objects or less. Larger objects get disrupted in the atmosphere and don't impact the surface, unless they are really big and can cause hypervelocity impact craters. This is where the 50 m number fits in. --JeffG 19:36, 29 April 2007 (UTC)

It's dependent upon too many factors to make such arbitrary statements. Such things as mass, composition, velocity, angle-of-entry must be taken into account. 210.54.245.44 01:59, 17 August 2007 (UTC)

[edit] Merge proposal

There is considerable overlap between these articles. There is little extra information it the meteor and bolide articles so it would be logical to merge them into this article. (I don't suggest the same for meteorite because that article is fairly long and stands alone.) Rsduhamel 16:44, 18 March 2007 (UTC)

Went ahead and did the first merge, except I thought it was more appropriate to merge meteor into meteoroid. Rsduhamel 21:24, 18 March 2007 (UTC)

Found a similar situation with micrometeoroid. Probably should be merged into meteoroid. Rsduhamel 05:13, 19 March 2007 (UTC)

A micrometeoroid is a meteoroid smaller than about 0.1 mm in size. It is also a word

synomous in the planetary astronomy community with cosmic dust. Merging is not a good idea. I suggest to look [[1]] for a clarification of definitions. Amara 20:51, 11 June 2007 (UTC)

[edit] merger seems awkward

I know that meteoroids are the thing and meteors are an ephemeral phenomena caused by meteoroids - but everyone know meteors and wold be confused, I think, by searching for meteors and coming to a meteoroid page. Seems a bit coercive - I'd rather see the meteoroid redirected to the meteor page--Smkolins 04:39, 21 March 2007 (UTC)

Since all meteors are meteoroids and all meteoroids are not meteors the requrested move page editors seem to prefer the corrent organization.--Smkolins 10:18, 16 April 2007 (UTC)

[edit] Definition of a fireball

I can't find an attributable quote from the IAU as to what a fireball is. Some quote it as "a meteor brighter than any of the planets" (which sounds like something they would say) and others as "a meteor brighter than magnitude -4" (which essentially says the same thing). Can someone find the real dope on this? Rsduhamel 18:46, 28 March 2007 (UTC)

[edit] head-on collisions

"Together with the Earth's orbital motion of 18 miles per second (29 km per second) speeds can reach 44 miles per second (71 kilometers per second) in head-on collisions. This means the meteor would also be in a retrograde orbit and a daylight (or near daylight) event as the Earth orbits in the direction of east a dawn"

This doesn't appear to make any sense to me... surely the direction of the Earth's orbit is pretty irrelevant? Anyway, wouldn't east at dawn be directly towards the Sun? So 3 things this section isn't making very clear: what is the actual direction of Earth's orbit, how does it affect the time of day at which a head-on collision with a meteor can occur and why does this mean that a meteorite can't strike at night? Sk8a H8a 06:38, 29 March 2007 (UTC)

I agree with the part about east at dawn being towards the sun rather than the direction of the orbit. But no the direction of the earth's motion isn't irrelevant - the question is how do you get the spread of meteoroid speeds - meteors coming from the night side have to play some kind of catch up. But the proper direction could be described as "down" at the equator at dawn, or east at noon at the equator. I think some of the rest of the variability of the meteoroid speeds comes from how far up the solar system the meteoroids come from. Most are claimed to come from either the asteroid belt or from comet evaporation. If they come from the asteroid belt that's a pretty defined area even if collisions that release them would kick them around some. If they come from comets it should increase their potential energy being converted to kinetic energy but most of the gravity well they are accelerating in is from nearer the sun. But it would be nice to be able to refer to some numbers on this. I'll check the east at dawn bit in the article.--Smkolins 10:27, 16 April 2007 (UTC)

All I could find on the net for the speeds is a quote in a discussion area - plenty of details but not reference-able easily in wikipedia - see[2] but here's a calculation of meteorite velocities [3]. Still worth doing more searching....--Smkolins 10:47, 16 April 2007 (UTC)

Hmmm. It appears that quite a few people noticed these horrible inaccuracies and wrote about them extensively on the talk page. Nice work, guys, but it is now June and those errors regarding earth's orbital motion were STILL IN THE TEXT until I corrected them today. That is far too long for inaccuracies to linger in an encyclopedic entry. Here is a proposal: next time you see something that is blatantly wrong in an article, how about fixing the error, instead of engaging in masturbatory actions on the talk page which, after two months, have not magically fixed the error on the REAL page, the one that, say, a young child just learning about the geometry of the solar system will dutifully copy word for word into its report on the solar system, only to be docked by the teacher for the gross inaccuracies contained within. If anyone needs a refresher on basic solar system geometry, why not google it? It's pretty easy to do. Just gaze for a brief moment at a simple diagram of the earth in orbit around the sun and you will see the truth of the situation. User:Tarotcards

[edit] Bolide definition

The original quote to a USGS web site was ...."an extraterrestrial body in the 1-10-km size range, which impacts the earth at velocities of literally faster than a speeding bullet (20-70 km/sec = Mach 75), explodes upon impact, and creates a large crater". While an accurate quote, the numbers given are nonsense and do not represent cutoffs that any cratering geologist, including those in the USGS, would use (eg 20 km/sec is actually faster than the average meteorite impact velocity). I changed the quote to the next sentence in the original source that far more accurately represents how cratering geologists actually use the term bolide. —The preceding unsigned comment was added by Zamphuor (talk • contribs) 02:13, 1 April 2007 (UTC). Whoops, forgot to sign. --Zamphuor 02:15, 1 April 2007 (UTC)

[edit] Ionization trail

There is a large quantity of uncited, unscientific information in this sub-section. Rather than remove it outright, I will tag it and hope another editor can verify these claims. I believe much of the material in that section is pseudoscience, especially in relation to "secure communications." Nimur 18:25, 21 May 2007 (UTC)

a simple google search for "meteor scatter secure communications" will reveal material that supports the information presented, including IEEE papers. it is not pseudoscience. here's a primer and one of the first results to come up:http://www.uksmg.org/deadband.htm. you can safely remove the tag. --Tase 13:40, 22 May 2007 (UTC)

[edit] Beliefs

Hm, I have come across some beliefs for shooting stars, one of which says that a shooting star resembles the passing of a person. Wonder if it is related and can be put on this page. --121.6.64.153 13:59, 15 August 2007 (UTC)

[edit] Mystery illness strikes after meteorite hits Peruvian village

Ok, I am not a Wikipedian anymore, but this may be worthy of some mention? We should follow this story for a week to see where it leads, and write a paragraph. Sounds like a moderately big meteor strike.

The disease symptoms may be due to (a) a few people legitimately getting sick due to some kind of fumes from the burning ground/surface of meteror, then followed by local mass hysteria, (b) radiation sickness, as the putative meteor may actually be a Chinese or Russian nuclear powered satellite, or (c) long awaited (better: feared) example of exposure to extraterrestrial bacterial organisms.

Note that (c) is legitimately possible, but also extremely unlikely, as all bacteria/fungi/viruses on Eath thus far studied have been of terrestrial origin. (With the one glaring exception - all life on Earth may originally be of extraterrestrial origin, such as bacteria from Mars meterorites landing here 3 billion years ago. I know that sounds like science-fiction, but it is considered a possibility by expbiologists.) RK 15:35, 18 September 2007 (UTC)

Mystery illness after meteor lands

Meteorite Lands in Puno, Peru Near Bolivia, Citizens Report Radiation Sickness

(LIP-ir) - Peru's Andina News Agency reported today that Puno's Regional Health Directorate sent a group of specialists to the Carancas community in the province of Chucuito near Bolivia to take samples of a meteorite that supposedly landed in the area...

Meteorites lands in Peru, near Bolivia

RK 15:21, 18 September 2007 (UTC)

[edit] Detection

Please help improve this article or section by expanding it. Further information might be found on the talk page or at requests for expansion. (January 2008)

Can objects smaller than 50m in orbit around the sun be detected individually? Are the orbits of any known? Are there any swarms that are not associated with meteor showers, or should readers be directed there for a catalog of known meteoroid groups? -- Beland (talk) 07:04, 2 January 2008 (UTC)