Talk:Asteroid belt

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name: A. Belt vs A. belt[edit]

which one is the correct form? Shouldn't "b" be capitalized since it is a name? Nergaal (talk) 01:34, 23 January 2008 (UTC)

Not a proper name, I think. Nouns in English (as opposed to, say, German) are not capitalized unless they refer to a particular named object. Other stars than the Sun will presumably be found to have "main belts" too: regions where orbits are nearly stable against the perturbations of major planets, so objects can collect and remain there there over time. It's kind of a close call—I would say "The Solar Main Belt" is proper, (as would be "The Alpha Centauri Main Belt", if there is one). Anyhow, I believe it is typically not capitalized (like "the sun", which is common but definitely incorrect, I think per IAU decree). "What's in a name?" :) Wwheaton (talk) 19:12, 23 April 2009 (UTC)

Collisions versus agglomeration[edit]

I would like to see a cite for the sentence that reads "collisions that occur at low relative speeds may also join two asteroids together." Really? Most collisions are at at least many hundreds of m/s up to typical impact speeds of 5 km/s -- does two asteroids ever join together 'softly' the way this reads?? —Preceding unsigned comment added by 128.148.116.88 (talk) 20:54, 11 November 2009 (UTC)

At one point the document says that the total mass of the belt is 4% of the mass of Earth's Moon. Another point in the document says that 99.9% of the mass of the belt has been lost. A quick Google calculation yields: ((mass of the Moon * 0.04) / (1 - 0.999)) / Earth mass = 0.492125876. Therefore, the original mass of the Asteroid Belt is estimated to be half an Earth mass. Another quick Google calculation yields mass of Mars / Earth mass = 0.107446849. Now that I have established that the Asteroid Belt could have been formed from a planet-sized object, I want to attack the idea that the rocks of the belt could be formed from accretion. Ceres, the largest object inhabiting the belt, has a mass of 0.00015 times that of Earth, and a surface gravity of 0.028 m/s^2. The Earth has a surface gravity of 9.81 m/s^2, or 350 times that of Ceres. The gravity of any planet is zero at the center. We approximate the pressure at the center of Ceres (from http://physics.info/pressure/practice.shtml) with (3.0 * (((6.67E-11 N) * (m^2)) / (kg^2)) * ((9.43E20 kg)^2)) / ((8 * Pi * (487.3E3 m))^4) = 7909.06946 pascals. The document on Metamorphic rock says that 1500 bar is required to form this rock, which is the type of rock that I would expect to form from dust in space. Note that 1500 bars = 150000000 pascals, and (1500 bars) / (7909.06946 pascals) = 18965.5687, that is, the pressure at the center of Ceres is 19 thousand times too small to form rock. Therefore, it is unlikely that the Asteroid Belt was not formed from a demolished planet. QED. This article is pablum for the masses, and should be removed for being unscientific. 98.81.162.188 (talk) 03:00, 28 February 2014 (UTC)

Rock is a type of material. Pressure is not required to form it; it was already present in the accretion disc (actually, already in the planetary nebula). Nothing has been QED'ed by you. --JorisvS (talk) 08:28, 28 February 2014 (UTC)
Rock forms under zero pressure in space? Would I then have to accept that the hand of God was at play? Or is the position that space is filled with random rock that readily collects into tight orbital planes that are separated by light-years? Please provide calculations to support your position, as words alone have zero value. 98.81.179.13 (talk) 13:34, 28 February 2014 (UTC)
The early (more massive) asteroid belt was scattered and materiel eroded away by Jupiter because Jupiter is the most massive planet and accreted first. This is also the reason Mars is somewhat on the wimpy size. The average density of Ceres is only 2.1 g/cm3 and most of the heavier elements (what astronomers casually refer to as rock) will be near the core. -- Kheider (talk) 15:17, 28 February 2014 (UTC)
My arguments are: the Asteroid Belt is what remains from a planet-sized object destroyed in the past; the rocks and dust that constitute the Asteroid Belt were not formed in space spontaneously with near-zero-pressure. I presume rock, whether massive or miniscule, is the product of planetary accretion. Planets are the factories that produce rock from the matter stars eject. Gravity is the machinery in planets that form rock, and with little gravity - no rock forms, as the pressure threshold required to form the crystalline structure is not exceeded. The unsubstantiated proposition that the rocks in the Asteroid Belt were the product of accretion under what-amounts-to zero pressure is fallacious, and abhorrent in that it "teaches" something akin to magic. I appear to be arguing with blind consensus, and as history has repeatedly shown, consensus is the enemy of science. Dissent is the factory that produces science, and argument is the mechanism that conceives a new understanding. I see no arguments here, just parroting of past statements with no understanding what those statements mean. 98.81.167.61 (talk) 02:44, 1 March 2014 (UTC)
Not rocks as in "boulders", but nano-sized particles consisting of rock. Follow that link if you don't understand this. --JorisvS (talk) 18:40, 28 February 2014 (UTC)
Rock is a crystalline structure. If by "rock" you mean a loose dust pillow made of "nano-sized particles", then I think we have nothing more to discuss as you have no intellectual integrity. 98.81.167.61 (talk) 02:44, 1 March 2014 (UTC)
A) Personal attacks such as that are not allowed, for good reasons. B) One can also have dust-sized particles of ices. You should review cosmic dust and interstellar cloud (look for "dust"). --JorisvS (talk) 11:24, 1 March 2014 (UTC)

Collisions, "Meteorites" content conflict with 298 Baptistina page[edit]

The following information conflicts with more recent information as mentioned in the 298 Baptistina page: "A September 2007 study has suggested that a large-body collision undergone by the asteroid 298 Baptistina sent a number of fragments into the inner Solar System. The impacts of these fragments are believed to have created both Tycho crater on the Moon and Chicxulub crater in Mexico, the relict of the massive impact which is believed to have triggered the extinction of the dinosaurs 65 million years ago". While the 298 Baptistina page (based on more recent research) states: "It was considered the possible source of the impactor said to have caused the extinction of the dinosaurs, a possibility ruled out by the Wide-field Infrared Survey Explorer in 2011." etc.86.84.5.177 (talk) 17:27, 22 February 2013 (UTC)


Origin of the term "belt"[edit]

The earliest quote Google Books finds is Mémoires de la Société royale des sciences de Liège, 1843, which reads in part "[...] the plane of the ecliptic and beyond Saturn or, conceivably, in the asteroid belt as suggested by Oort." But since Oort lived 1900-1992, this must be a mistake ("1943" instead of 1843).

More reliable are:

  • Robert W. Gibbes et al., Eds., Proceedings of the American Association for the Advancement of Science, First Meeting, Held at Philadephia, September 1848, 1849, p. 60 (On the Zodiacs of the Asteroids): "Prof. [J. S.] Hubbard of the Washington Observatory stated to the Association that he was then engaged in computing the Zodiacs of the Asteroids. The term Zodiacs, as here applied, he defined as referring to the zone or belt within which are included all possible geocentric positions of the particular asteroid in question: and the object in thus determining these belts was to facilitate researches into the past history of these remarkable bodies; since in most cases, the question of identity of a missing star, with any asteroid, may be settled at once by a simple inspection of the Zodiacs."
  • Alexander von Humboldt, Cosmos: A Sketch of a Physical Description of the Universe, Vol. I, Harper & Brothers, New York (NY), 1850, p. 44: "[...] and the regular appearance, about the 13th of November and the 11th of August, of shooting stars, which probably form part of a belt of asteroids intersecting the Earth's orbit and moving with planetary velocity" (translated from the German by E. C. Otté). The 1845 edition does not use that expression.
  • The Christian Examiner, Vol. LVII (July-November 1854), p. 219: "For in Professor Peirce's demonstration of this hypothesis, he shows that the ring is sustained by the power of the exterior satellites; and remarks that the belt of asteroids just within the powerful masses of Jupiter and Saturn is in that place where it is most nearly possible for a ring to be sustained about the Sun." The article qives its reference as Benjamin Peirce, On the constitution of Saturn's ring, Astronomical Journal, Vol. 2, No. 3, pp. 17-19 (16 June 1851), but that article never mentions the word "belt". However, see The Edinburgh New Philosophical Journal 1857 quote, below.
  • Joseph Allen Galbraith and Samuel Haughton, Manual of Astronomy, Longman, Brown, Green, and Longmans, London, 1855, pp. 13-14: "In the annexed figure, which is drawn to scale, the belt of Asteroids enclosed between the orbits of Flora and Euphrosyne is represented in its true position and breadth, lying between Mars and Jupiter. [...] There are, without doubt, many more bodies than the 33 mentioned in the Table circulating round the Sun within the limits of this belt [...]"
  • Thomas Anderson, William Jardine, John Hutton Balfour, Henry Darwin Rogers, (Eds.), The Edinburgh New Philosophical Journal, Vol. 5 (January-April 1857), p. 191: "[Professor Peirce] then observed that the analogy between the ring of Saturn and the belt of the asteroids was worthy of notice."
  • Hannah Mary Bouvier Peterson, Bouvier's Familiar Astronomy, Childs & Peterson, 1857, p. 57: "[The asteroids] are situated in a belt or zone only about nine hundred million of miles in width."
  • Jacob Ennis, The Origin of the Stars, 1867, p. 292: "[The asteroids] are probably a few hundred in number, about eighty having been discovered in the last twenty years, and they are included within a belt about 150,000,000 miles broad. In view of the dimensions of the rings which formed the planets as given in the thirtieth section, we cannot suppose that a single ring occupied all the space within the asteroid belt."
  • Albert Taylor Bledsoe, Editor, The Southern Review, Vol. VIII, No. 15 (July 1870), p. 165: "If this [nebular] hypothesis be true, it is at least conceivable that while in one stage of the condensation great planets should be formed, in another period there would result a multitude of small bodies similar in all respects to those which constitute the great asteroid belt".

In conclusion, the term "belt" (as a span of latitude) had long been in use to designate the zodiac (and features of Jupiter). "Asteroid belt" seems to have been used for the first time by a translator of Humboldt, in 1850, but that may be accidental (the original German text does not use the German word "gürtel" ("belt"); "asteroidengürtel" appears in the 1879 edition, though). Widespread use apparently begins ca. 1851, probably under the aegis of American astronomer Benjamin Peirce, and was undoubtedly influenced by the concept of belt or ring borrowed from the nebular hypothesis. Urhixidur (talk) 17:59, 21 November 2008 (UTC)

Digging further into German sources, G. A. Jahn, > Unterhaltungen für Dilettanten und Freunde der Astronomie, Geographie und Meteorologie, Leipzig, 1852, p. 340: "[...] so dass man jetzt deren 20 kennt die man als Stellvertreter eines grössern Planeten zwischen der Mars und der Jupitersbahn betrachten kann obgleich sie einen so breiten Gürtel bilden dass die in der Bode schen Reihe für sie bestimmte Entfernung nicht mehr passt", which my poor German translates roughly as "[...] so that one knows some 20 [planetoids] now, and placing them between the orbits of Mars and Jupiter forms so broad a belt that the distance determined in Bode's Law no longer has any meaning." Not very convincing, and no other German book before that date (1852) mentions "gürtel" along with "Ceres, Pallas, Vesta". Urhixidur (talk) 18:54, 21 November 2008 (UTC)

Rotation Rate[edit]

The cited article about a lower limit on rotation rates (Rossi, Alessandro (May 20, 2004). "The mysteries of the asteroid rotation day". The Spaceguard Foundation. http://spaceguard.esa.int/tumblingstone/issues/current/eng/ast-day.htm. Retrieved 2007-04-09.) is no longer available online. It seems to be contradicted by this article: http://www.nature.com/nature/journal/v386/n6621/abs/386154a0.html which states that "Moreover, our calculations suggest that the observed trend in the mean spin frequency for different classes of asteroids (2.2 d–1for C-type asteroids, 2.5 d–1 for S-type, and 4.0 d–1 for M-type) is due to increasing mean density, rather than increasing material strength." Can we find a current reference for the currently cited article, and should we include the contrary view in the article? Delrayva (talk) 04:36, 23 December 2009 (UTC)

Composition[edit]

Why do the proportions of the three types of asteroids add up to about 103 percent. Rounding certainly can't be the error factor here.

C-type "more than 75 percent" S-type "17 percent" M-type "10 percent" —Preceding unsigned comment added by 159.121.204.129 (talk) 19:35, 27 May 2010 (UTC)

Because the third number was also determined indepently, and not by substracting the first two from one hundred. --129.13.72.198 (talk) 11:49, 29 April 2011 (UTC)

"Dust particles"[edit]

"The remaining bodies range down to the size of a dust particle."

Are dust paricles possible? I thought they´d be wiped out of the solar system by the pressure of the solar radiation. --129.13.72.198 (talk) 11:43, 29 April 2011 (UTC)

You might want to read the Collisions section. In short, it's an ongoing cycle of dust generation through collisions and loss from solar radiation.—RJH (talk) 14:39, 29 April 2011 (UTC)


"Size chart of the largest Asteroids"[edit]

Someone should create a size chart like the one for the Solar System article. Start with the largest, Ceres, and end with the known smallest one. A size chart for the Centaurs would be neat too. Thank you. Chuck 17:42, 20 July 2012 (UTC) — Preceding unsigned comment added by Triton66 (talkcontribs)

Composition[edit]

Many asteroids are known to be partly composed of ices through their densities, notably Ceres itself. So why would it be so unexpected to find water (vapor)? Evidence of (past) water has even been found on dry Vesta. --JorisvS (talk) 15:25, 23 January 2014 (UTC)

@JorisvS - Thanks for your comments - text has been updated (after a closer look at the cited reference) as follows => The finding is unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."< ref name="NASA-20140122">Harrington, J.D. (22 January 2014). "Herschel Telescope Detects Water on Dwarf Planet - Release 14-021". NASA. Retrieved 22 January 2014. </ref> - in any case - thanks again for your comments - and - Enjoy! :) Drbogdan (talk) 16:14, 23 January 2014 (UTC)
Yes, definitely better:). Thank you. --JorisvS (talk) 16:15, 23 January 2014 (UTC)
It's still a rather silly thing to say, isn't it, since comets are defined by "spouting jets and plumes"? So they're saying it's surprising that Ceres spouts jets and plumes, because only things that spout jets and plumes are usually thought to spout jets & plumes. It's a badly worded catch for a news release, not something we should be quoting. The point they're trying to make is that while some smaller, outer asteroids were known to display cometary activity, prompting the IAU in 2006 to reject the distinction between asteroid and comet by creating the category SSSB, now the largest asteroid (and a DP rather than a SSSB) has been shown to exhibit similar behaviour, blurring the lines even further. Certainly we can find a wording that isn't intellectually challenged. — kwami (talk) 21:13, 1 March 2014 (UTC)