Talk:Annus

message: Does anybody happen to know how annus came to be neuter in this scientific usage? Google suggests that it actually is called annum here, but I wonder... It is definitely and solely masculine in classical Latin, and as far as I can see, in medieval Latin as well. So I suppose it must be fairly recent? Maybe taken from the accusative case, as in per annum? T.a.k. 4 July 2005 21:02 (UTC)
:According to the Oxford English Dictionary, per annum first appeared in the early seventeenth century, and is derived from the Latin accusative case of annus. However, my knowledge of Latin is limited, so I'm not sure how that relates to being neuter. — Joe Kress 5 July 2005 07:41 (UTC)
It's not neuter. It's masculine. Masculine accusative has the same suffix as neuter nominative. Woodwalker 12:58, 5 June 2006 (UTC)
replies: text: As such, I think the article should reflect that the etymology is the accusative because it was derived from it's use in the phrase "per annum," and at least state that the plural is annos or annums (rather than, for example, anna).  Eebster the Great (talk) 03:33, 3 March 2009 (UTC)
thread_title: Masculine or neuter?

message: Hi.  Contrary to the assertion of Georgia Guy, Ka is a commonly used abbreviation in the scientific literature, particularly by earth scientists and geophysicists working on time scales of 10^3 to 10^5 years.  As per Georgia Guys request, I submit proof that Ka is a commonly used term.  These are the first ten references from a search in the ISI Web of Science indexing service that contain "Ka" in their title, abstract or keywords that use Ka in the sense of kilo-annum.  The search retrieved some 14,000 articles.  This selection of papers represented 10 of the first 15 hits (the other five used Ka in a different sense, for example, as k-alpha in x-ray spectroscopy), suggesting that over 9300 of the hits used Ka in the sense suggested in this article.  Since the term follows logically from Ma and Ga (also commonly used terms), it should stay here and not be transfered to Millennium (although perhaps it could be included in Millennium).
:Channell, J. E. T., 2006. Late Brunhes polarity excursions (Mono Lake, Laschamp, Iceland Basin and Pringle Falls) recorded at ODP Site 919 (Irminger Basin). Earth And Planetary Science Letters, 244(1-2): 378-393. 
:Clarke, M. L. and Rendell, H. M., 2006. Effects of storminess, sand supply and the North Atlantic Oscillation on sand invasion and coastal dune accretion in western Portugal. Holocene, 16(3): 341-355. 
:Cucci, L., 2005. Geology versus myth: the Holocene evolution of the Sybaris Plain. Annals Of Geophysics, 48(6): 1017-1033. 
:Li, S. H. and Sun, J. M., 2006. Optical dating of Holocene dune sands from the Hulun Buir Desert, northeastern China. Holocene, 16(3): 457-462. 
:Maher, B. A. and Hu, M. Y., 2006. A high-resolution record of Holocene rainfall variations from the western Chinese Loess Plateau: antiphase behaviour of the African/Indian and East Asian summer monsoons. Holocene, 16(3): 309-319. 
:Pisias, N. G., Heusser, L., Heusser, C., Hostetler, S. W., Mix, A. C. and Weber, M., 2006. Radiolaria and pollen records from 0 to 50 ka at ODP Site 1233: continental and marine climate records from the Southeast Pacific. Quaternary Science Reviews, 25(5-6): 455-473. 
:Reid, E. and Thomas, M. F., 2006. A chronostratigraphy of mid- and late-Holocene slope evolution: Creagan a' Chaorainn, Northern Highlands, Scotland. Holocene, 16(3): 429-444. 
:Sinha, R., Smykatz-Kloss, W., Stuben, D., Harrison, S. P., Berner, Z. and Kramar, U., 2006. Late Quaternary palaeoclimatic reconstruction from the lacustrine sediments of the Sambhar playa core, Thar Desert margin, India. Palaeogeography Palaeoclimatology Palaeoecology, 233(3-4): 252-270. 
:Turney, C. S. M., Kershaw, A. P., James, S., Branch, N., Cowley, J., Fifield, L. K., :Jacobsen, G. and Moss, P., 2006. Geochemical changes recorded in Lynch's Crater, Northeastern Australia, over the past 50 ka. Palaeogeography Palaeoclimatology Palaeoecology, 233(3-4): 187-203. 
:Zhang, Z. H., Zhao, M. X., Eglinton, G., Lu, H. Y. and Huang, C. Y., 2006. Leaf wax lipids as paleovegetational and paleoenvironmental proxies for the Chinese Loess Plateau over the last 170 kyr. Quaternary Science Reviews, 25(5-6): 575-594.
Rickert 00:44, 7 May 2006 (UTC)
thread_title:  Ka 

message: I would propose to merge this article with the articles Mya (unit), Bya and Gya. The suffixes do not make any difference to what the article is really about: the use of the unit annum in science. One article will be much clearer than three or four. We can have redirects on the other pages to cover the lot. Woodwalker 12:57, 5 June 2006 (UTC)
replies: text: I totally agree.Rolinator 10:07, 29 October 2006 (UTC)
thread_title: Merging articles

message: Why is this defined as an average Julian calendar year? It would seem to make sense to use the Gregorian since the Julian hasn't really been used in the west for about 250 years.... Does anyone know the rationale for this? 96.248.231.158 (talk) 04:51, 8 July 2008 (UTC)
replies: text: It is both historical and mathematical. Both average Julian years and mean tropical years were used by Simon Newcomb, the director of the American Nautical Almanac Office within the United States Naval Observatory, during the nineteenth century for various astronomical calculations. For high precision, mean tropical years are not suitable because their value changes from year to year. The average Gregorian year could be used because its value is constant and is known precisely, but the average Julian year requires fewer digits. Throughout most of the twentieth century, variable tropical years were used. Possibly because Newcomb had preferred the average Julian year over the average Gregorian year, in 1976 the XVIth General Assembly of the International Astronomical Union required that average Julian years be used beginning in 1984 (several years advance notice was needed to prepare almanacs). Another reason may be that the smallest decimal multiple of the average Julian year is only 100 years (shifting the decimal point two places in calculations), whereas 10,000 years (four decimal places) are needed for Gregorian years. So the three multiples of 100, 1,000, and 10,000 Julian years provide greater convenience than the single multiple of 10,000 needed if average Gregorian years were used. — Joe Kress (talk) 03:19, 9 July 2008 (UTC)
thread_title:  ''Julian'' years? 

message: I deleted "exactly" before 365.25, because I think a year refers to a revolution of Earth around the sun, variously defined, but usually with respect to the rest of the Universe.  If years were precisely 365.25 days of 24 hours each, that would avoid the necessity of altering the Julian calendar, but the actual duration of a year is not so exact; it depends on the mass and momentum of the earth and gravitational influences on it.  So it's variable, and unrelated to the length of a day. Unfree (talk) 01:14, 17 June 2009 (UTC)
replies: text: The article does not indicate where the definition came from. This is a serious flaw. --Jc3s5h (talk) 02:15, 17 June 2009 (UTC)
replies: text: I'm removing the indefensible phrase about a revolution around the Sun, and adding a ref for the exact value of 365.25 days and 86,400 seconds per day. This information was already in Julian year (astronomy) which brings up the possibility that this article be merged with that article rather than year. — Joe Kress (talk) 20:40, 17 June 2009 (UTC)
replies: text: Joe, I don't agree that the reference provided for the definition gives sufficient support for the definition. The reference says "Although there are several different kinds of year (as there are several kinds of day), it is best to regard a year as a julian year of 365.25 days (31.5576 Ms) unless otherwise specified." This seems more like a suggestion to astronomers rather than a definition. Since the word "annum" is widely used in law and finance, I don't think a suggestion aimed at astronomers can even be thought of as a suggestion to non-astronomers. --Jc3s5h (talk) 21:46, 17 June 2009 (UTC)

text: You have a point. Besides its use in astronomy, I was thinking of its use in dendrochronology and geology, which I doubt have precise year lengths. I completely ignored its use in law, where I believe various court cases have determined it to be a Gregorian calendar year, from a specified date in one year to the day before that date in the following year. Thus we may need several definitions, one for each area of use. Even in astronomy, a or annum is rarely used—yr is much more frequent, as it is in dendrochronology. I should emphasize that, at least in astronomy, only the symbol may vary. The exact value of 365.25 days was required by the IAU (1976) System of Astronomical Constants for use in ephemerides, implemented January 1, 1984. — Joe Kress (talk) 22:34, 17 June 2009 (UTC)
thread_title:  Revolutions of Earth around the Sun 

message: "For example, the dinosaur species Tyrannosaurus rex was abundant approximately 65 Ma (65 million years) ago "
"For example, the formation of the Earth occurred approximately 4.57 Ga (4.57 billion years) ago."
Should the "ago"s be moved inside the parenthesis so it reads "...approximately 4.57 Ga (4.57 billion years ago)."?
The article says that "ago" can be implied. I'm not a geologist so I don't know if something like "4.57 Ga" is almost never written with "ago" following it in the literature. If so, maybe it should be in the parenthesis to get the reader comfortable with it.He Flips (talk) 15:09, 7 July 2009 (UTC)
replies: text: Although "ago" is implied in geology and paleantology and sometimes in celestial mechanics, the latter also predicts the motion of solar system bodies millions or billions of years into the future, so "ago" is definitely not implied there. — Joe Kress (talk) 20:48, 7 July 2009 (UTC)
thread_title:  "Ago" is Implied 

message: This was raised above, but not answered.
Why is the article located at "annum" when the Latin word is annus?
Why does the article talk about "kiloannum", "meg[a]annum" etc., when the straightforward expansion of "ka" would be "kiloyears" or, if it absolutely must be Latin, "kiloannus" or "kiloanni"? Whose lead are we following here? I do not see any reference attached to the expansion "kiloannum". --dab (𒁳) 13:58, 17 February 2010 (UTC)
replies: text: In my experience, ka, Ma, etc., are usually read as annum in the geological community even though this clearly incorrectly from the Latin root.  Google searches like:   show examples of this while the more logical annus form is almost never used (though some people recommend it), e.g.  .  Even more fun is the bastardized forms like kilo-annums, mega-annums.  Dragons flight (talk) 00:00, 18 February 2010 (UTC)
thread_title: Article title