Talk:Tropical year

Karl, lets settle on a convention about Latin, Greek, English words. I think we should stick to whatever is current in English. If you start to Romanize or Hellenize English words, there is no end - anglosaxons completely screw up foreign words; e.g.:

equinox would be aequinox (equus = horse, aequus = equal (sic!))

Homer would be Homeros

Now the English word is perihelium, not perihelion; like the stuff is helium, not helion. -- Tompeters

This would be a good argument, except for the fact that it's "perihelion" in English. What dictionary are you using that says otherwise? --Zundark, 2001 Oct 25

OK, I screwed up -- Tompeters

Bad example: Helium ends in -ium because it was first found spectroscopically in the sun and they thought it was a metal: and metals get -ium or -um on the end e.g. Thorium, Hafnium, Aluminium, Neodymium, Molybdenum. If the naming convention for noble gases was followed strictly, Helium actually should be called Helion, though no-ones going to rename it at this late date - Malcolm Farmer

Thanx for pointing that out, I never noticed. Good to see someone writing Aluminium, americans usually say aluminum.

NPOV violation

This article is written from a northern-hemisphere perspective and needs some revising to make it hemisphere-neutral. Terms like "vernal equinox" and "summer solstice" are deprecated because they cause excessive confusion, especially for people who live south of the Equator. Terms like "Spring equinox" and "Summer solstice" should only be used in contexts where the local equinox or solstice is important (like the timing of Pagan festivals); when referring to the equinox or solstice that occurs in a particular month regardless of season, the name of that month should be used to identify the equinox or solstice (March equinox, December solstice).

I suggest that "vernal equinox" be changed to "March equinox", along with other similar changes to remove references to specific seasons where they are inappropriate. It would also be helpful to clarify why the March Equinox is important (because our calendar is based on the old Roman calendar, and the old Roman calendar began at the March equinox). --B.d.mills 02:32, 28 Feb 2005 (UTC)

I cannot agree with your suggestion for two reasons. First, relative to the astronomical portion of the article, the International Astronomical Union, with the concurrence of all of its member countries in the southern hemisphere, defines the vernal equinox as the point where the Sun crosses the celestial equator on its way from south to north, applying that definition world-wide, including the southern hemisphere. Second, for the calendrical portion, almost all churches, both East and West, define 21 March to be the vernal equinox, in the Julian and Gregorian calendars respectively, with at least the Roman Catholic Church specifically stating that this definition applied to all lands recently discovered (before the 1582 promulgation of the Gregorian calendar) in the southern hemisphere. Consequently, all Christians in the southern hemisphere continue to celebrate Easter in the northern spring. In this case, calling it the March equinox would be repetitive. As a compromise, the present clarification "(northern)" in the first paragraph could be expanded into a full statement that all seasons are northern hemisphere seasons. — Joe Kress 03:39, Mar 2, 2005 (UTC)

I disagree with the assessment because it does not remove the seasonal ambiguity. A statement that "all seasons are northern hemisphere seasons" would require further research to discover what the seasons are in the southern hemisphere. Therefore, it is of limited geographic scope and is not suitable for an international audience. Wikipedia has a boilerplate tag "Limitedgeographicscope" that can be used for this. One may as well refer to the equinox as the March equinox throughout, and have a single blanket statement that the March equinox is commonly known as the vernal equinox. The only objective reason for preferring vernal equinox to March equinox is if the IAU mandates the use of that term exclusively; and I have not yet found any indications that that is the case. --B.d.mills 11:13, 23 Apr 2005 (UTC)

Ephemeris Time

The article now says:

The time scale is Terrestrial Time (formerly Ephemeris Time) which is based on atomic clocks

I don't understand this. One could understand this as "Terrestrial Time was formerly called Ephemeris Time". This is not the case. Ephemeris Time is different from Terrestrial Time; and is not based on atomic clocks. Terrestrial Time is now used a lot where Ephemeris Time used to be used. But wouldn't the formulae be different in the past if they used Ephemeris Time in the past? Until someone who really understands this, sorts this out, I will delete the text in parentheses "(formerly Ephemeris Time)" -- Adhemar