Talk:Equinox

Which of the following is a better sentence?

  "A zebra is a zoological term for when an animal has a long neck."

  "In zoology, a zebra is an animal with a long neck."

The former sentence is how this article and the ones on vernal equinox and autumnal equinox were written.

Improving an article is good, but there is no need for unfriendly remarks. Patrick 21:48 Nov 2, 2002 (UTC)

lol Lir 00:06 Nov 3, 2002 (UTC)

"The time at which the sun passes through each equinox point can be calculated precisely—so the equinox is actually a particular moment, rather than a whole day."

I was wondering, how accurate the equinox can be found out. Certainly the mathematically exact moment can not be calculated. The sea quake in the Indian ocean 2004 tilted earths axis by several centimeters so with enough wobbling or vibrations there might even be multiple spring/autumn equinoxes per year. So, is the calculated precision of equinoxes a matter of seconds, ms, us, ns?

There is a difference between the "rotation axis" of the earth and the geographical location where this axis intersects the surface. Because of conservation of angular momentum, the rotation axis cannot be changed by events on earth and so the celestial equator is fixed in space and equinoxes can be determined very accurately (sorry to admit I do not know the current margins). The wobbling mentioned is the movement of the earth's crust relative to the rotation axis and has no bearing on the time of equinox. −Woodstone 12:04, 2005 Mar 28 (UTC)

Factual accuracy questions

This article makes two claims which contradict others on the 'pedia. I am uncertain of exactly which is right/wrong, but I suspect this one is:

Article claims that at equinoxes day/night are equal. Vernal equinox article says that is not true, and that day/night equal day occurs a few days before or after equinox.
Article claims that at poles sun passes from six month day to six month night & vice versa. Other articles (Midnight sun, Polar night) imply the period at the poles is not quite six months day/six months night, but slightly less.

Also, article should explain what a sidereal equinox is, and how it differs from a normal one. --137.111.7.212 10:27, 9 September 2005 (UTC)[reply]

It is not a question of right or wrong. It depends on the definition of day versus night.

Simple definition:
- day is the period that the true position of the middle of the sun is above the horizon
- the day and night are equal at the equinox
- polar night and day are half a year each
More common definition:
- day is the period that some direct light of the sun reaches the ground in absense of local obstacles
- this definition makes the day longer by some 7 minutes or more (width of solar disk plus atmospheric refration)
- equal day and night occurs a few days before the vernal equinox and a few days after the autumnal equinox
- polar day is much longer than polar night (and very long twilight)

I will add a short explanation in the text and remove the banner.−Woodstone 20:31:58, 2005-09-09 (UTC)

In response to the suggestion that the entry for 'Equinox' be merged with the entry for 'Equinoctial Point', I favour the retention of the term 'Equinox'. The purpose of an encyclopaedia is to provide access to information to people who may know little about a topic. Otherwise why are they looking it up? Equinox is a term more likely to be used in such cases. The term 'Equinoctial point' can be covered within that entry and in its own entry if more detail is required. P J Lock 130.220.79.98 00:17, 28 September 2005 (UTC).[reply]