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fagricipni
2015-Sep-05, 02:47 PM
I am hoping some of the English-speaking Southern Hemisphere residents can give me some help with this question. Which equinox is referred to by the phrase "vernal equinox" in the Southern Hemisphere. I had until recently thought that the northward equinox was the vernal equinox even in the Southern Hemisphere. I had read that in the equatorial coordinate system right ascension was measured from a zero at the "vernal equinox". Right ascension is measured from the northward equinox in both hemispheres, but as some people who are all in the Northern Hemisphere are making a big point of "vernal" means spring, and the spring equinox is indeed the southward equinox in the Southern Hemisphere. My original understanding was that the "vernal equinox" had become astronomical jargon for northward equinox, despite the fact that "vernal" alone meant spring; but some Northern Hemisphere people are arguing that the fact that "vernal" means spring means that the meaning of "vernal equinox" is indeed the southward equinox in the Southern Hemisphere.

So I figured I see if I could get some information on actual usage in the Southern Hemisphere? How is "vernal equinox" actually used in Southern Hemisphere publications?

StupendousMan
2015-Sep-05, 11:45 PM
Examples of astronomical journals published in the southern hemisphere which refer to the "vernal equinox" -- from a quick search in ADS:

http://articles.adsabs.harvard.edu/full/1990MNSSA..49...99D uses "vernal equinox" to mean "Sun crosses celestial equator heading north"
http://articles.adsabs.harvard.edu/full/1966MNSSA..25...59M ditto

Robert Tulip
2015-Sep-06, 03:56 AM
The assumption that vernal means March is a good example of imprecise language and of how southern perspectives are routinely ignored. For precision it would be better to refer to the March and September equinoxes, or if vernal is used then qualify it with "northern". Eurocentric perspectives colonise language, as in descriptions of Australia and New Zealand as part of the "global north" in economic literature. Good luck on changing that.

Hornblower
2015-Sep-06, 01:29 PM
This is just a case in which astronomers and navigators have co-opted a word for use as a convenient name for an agreed-upon mathematical benchmark. When I first saw "vernal equinox" in the Nautical Almanac as a kid I had no idea that it meant spring in the ancestral language, but I knew that it was the March equinox. If I had not seen "autumnal" for the September equinox I would not have given it a second thought.

Robert Tulip
2015-Sep-09, 01:27 AM
This is just a case in which astronomers and navigators have co-opted a word for use as a convenient name for an agreed-upon mathematical benchmark. When I first saw "vernal equinox" in the Nautical Almanac as a kid I had no idea that it meant spring in the ancestral language, but I knew that it was the March equinox. If I had not seen "autumnal" for the September equinox I would not have given it a second thought.

The comparison with the use of "planet" to describe Pluto is instructive, with astronomers insisting on a precise use of terminology to prevent confusion.

Restriction of "vernal equinox" to mean "March Equinox" (or the first point of Aries in right ascension (https://en.wikipedia.org/wiki/Right_ascension)) actually is worse in terms of precision than calling Pluto a planet. It completely ignores the perspective of people in the southern hemisphere, where the vernal or spring equinox occurs in September. And it is not merely a geocentric error, like the words sunrise and sunset, but actually a flat earth error, because assuming the northern perspective is universal implies the southern hemisphere does not even exist.

fagricipni
2015-Sep-09, 03:20 AM
One of the claims that I have seen is that the definition of Easter as being on "the first Sunday after the full moon* on or after the vernal equinox" is wrong because Easter is not observed in September or October in the Southern Hemisphere. My own viewpoint was and still is that "vernal equinox" is astronomical jargon for the northward equinox and thus is not incorrect. I, personally, prefer to use "northward/southward equinox" because "autumnal" does imply "autumn" too much. Also, the solstices do not have special names like "vernal", I have always seen "summer" and "winter" solstice. So while I would argue that "vernal equinox" is astronomical jargon for the northward equinox, the other three events do not have such unambiguous names; so I personally use "northward/southward equinox" and "north/south solstice" (or "northern/southern solstice") in writing, but I do not claim that "vernal equinox" is wrong either.

* Yes, I know that the "full moons" and "equinoxes" in question are ecclesiastical events, not the true astronomical ones; but that point is not in dispute, just the reference to the "vernal equinox".

Jens
2015-Sep-09, 04:07 AM
Restriction of "vernal equinox" to mean "March Equinox" (or the first point of Aries in right ascension (https://en.wikipedia.org/wiki/Right_ascension)) actually is worse in terms of precision than calling Pluto a planet. It completely ignores the perspective of people in the southern hemisphere, where the vernal or spring equinox occurs in September. And it is not merely a geocentric error, like the words sunrise and sunset, but actually a flat earth error, because assuming the northern perspective is universal implies the southern hemisphere does not even exist.

I agree that it's a worse error than calling Pluto a planet, because Pluto is the name and you don't have to use the term planet to describe it, whereas the vernal equinox is actually what it's called, not the description.

But saying it's a flat earth error seems to be going a bit too far. Do you mean that we shouldn't say it's night because it's not so on the other side of the planet?

The issue with the vernal equinox isn't really a problem but it's just confusing. If we call it the vernal equinox in the northern hemisphere and people in the southern hemisphere call it the autumn equinox, there's really no problem except when two people arrange to meet on the spring equinox, and one lives in the north and the other the south.

But the same thing can happen when we say, "I'll come visit during the summer vacation." And going back to my previous example, if I say "I'll call you in the evening" and I'm talking to somebody in Europe, it's unclear whether I mean my evening or their evening.

Robert Tulip
2015-Sep-09, 04:31 AM
Do you mean that we shouldn't say it's night because it's not so on the other side of the planet?


That is different. No one claims a timing for night is universal for astronomy, whereas they do make that claim in practice for the vernal equinox, in language if not in intent.
the same thing can happen when we say, "I'll come visit during the summer vacation." And going back to my previous example, if I say "I'll call you in the evening" and I'm talking to somebody in Europe, it's unclear whether I mean my evening or their evening. Your point about the ambiguity and confusion arising from imprecise use of terms like summer and evening applies equally to the use of vernal equinox without the qualification 'northern'.

fagricipni
2015-Sep-09, 12:18 PM
No one claims a timing for night is universal for astronomy, whereas they do make that claim in practice for the vernal equinox, in language if not in intent. Your point about the ambiguity and confusion arising from imprecise use of terms like summer and evening applies equally to the use of vernal equinox without the qualification 'northern'.

But almost no one uses the word "vernal" to mean spring any more. We don't speak of "vernal flowers", but "spring flowers". "Vernal" is very rarely currently used except in the phrase "vernal equinox", so it could be argued that "vernal equinox" is like the expression "hot dog"; it no longer means the simple sum of its parts. This is why I asked about how it is actually used in Southern Hemisphere publications.

BTW, Are you from the Northern or Southern Hemisphere?

(I'm from the Northern Hemisphere.)

Ken G
2015-Sep-09, 07:44 PM
Actually, we still face certain inconsistencies if we regard the "vernal equinox" as meaning the "March equinox." That is, it is inconsistent with the way the solstices are usually referred to. The most typical way I've seen the solstices named is the "summer solstice" and the "winter solstice", rather than the "June solstice" or "December solstice" (which you do sometimes see, but I've almost never seen that), so those are specific to their hemispheres and is not universal language. Such non-universal language is not uncommon when it comes to time-related notions-- for example, we talk about "3 o'clock", and then go on to further specify where we mean that by giving a time zone. We sometimes even hear times as being in "Greenwich mean time", rather than "UT", so the former is an example of saying that a time is endemic to the place it applies, whereas the latter attempts to think of a time as a universal number. So I think the simple truth is, astronomical conventions are very mixed up on the issue of whether our labels should explicitly include the locations in which they are intended to apply, like "summer solstice" or "3 o'clock Greenwich mean time", or if they are intended to be universally applied labels like "March equinox" or "3:00 UT". I'm afraid that navigating inconsistent jargon is not unusual in astronomy, so more important than which convention we are using, is being clear which convention we have chosen! In that light, the entire phrase "vernal equinox" should probably not be used at all, and especially not to mean March equinox, because that is like using "summer solstice" to mean the June solstice. It's not a perfect analogy, because the word "summer" is still used in other contexts and "vernal" isn't, but still, it's language that sounds like it means something other than what it does mean, so that's introducing ambiguity. Ambiguity is worse than picking a nonstandard convention but being clear about it.

StupendousMan
2015-Sep-10, 12:36 AM
It's fine for people to talk about the choice of words in the technical literature in a thread on a bulletin board. It can entertain us. Until people with the same opinion start to write textbooks and influential journal articles, nothing will change.