The Equinox is the day where the sun passes directly over the equator in its Northward and Southward movements between the Tropic of Cancer and the Tropic of Capricorn. This topic is often used in discussions as evidence in favor of a Round Earth. Round Earth proponents have popularly made two claims for this day:
- The sun will rise from the east on this day for all locations on earth
- The earth will experience equal times of day and night
We find, however, both of these claims to be untrue.
The sun does not rise from the east for all locations on earth. It is admitted by academia that the sun is often displaced by several sun diameters from east on this day, with an allegation that it is only from the equator where the sun rises from the east.
Further, it is admitted by academia that equal times of day and night do not occur for this day all over the earth. The day of equal day and night is location and time specific. The period of equal day and night does not occur until several days after or before the equinox and, for some locations, the period of equal day and night does not occur for a time period measured in weeks away from the day of the equinox.
Oxford Dictionary defines the Equinox as:
"The time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about 22 September and 20 March)."
Late Middle English: from Old French equinoxe or Latin aequinoctium, from aequi- ‘equal’ + nox, noct- ‘night’.
Myth I: Direction of Sunrise and Sunset
“ Does the equinox sun really rise due east and set due west?
The March equinox signals spring in the Northern Hemisphere and autumn in the Southern Hemisphere. On this day, the sun rises due east and sets due west.
It may seem counterintuitive. But it’s true no matter where you live on Earth. ”
Equinox Sunrise Not from the East
“ Why is the equinox important for permaculture?
One of the first questions my PDC instructor posed to us was, “where does the sun rise?" Well everyone knows the answer to that; the sun rises in the east. No brainer. Alas, we were wrong. Unless you live at the equator, the sun does not rise directly in the east. ”
Russel D. Sampson of the University of Alberta informs us that the sun does not actually rise due east on the equinox, and is displaced from the east by multiple sun-diameters. Inventive special pleading is therefore invoked, attributing the inability of prediction to meet observation to "refraction":
“ The original motivation for this paper was the Journal article by Attas & McMurry (1999) entitled “Nailing the Equinox Sunrise.” In the article it is stated that “on the equinox, the Sun should rise due east.” Since the Sun crosses the celestial equator at the equinox, and since the celestial equator crosses the horizon at 90º and 180º azimuth (due east and west), that statement appears on the surface to be correct. Once the effects of astronomical refraction are considered, however, the phenomenon becomes a little more complex.
...In this paper the unrefracted Sun is referred to as the geometric Sun. From the definition of sunrise and sunset, the azimuthal location of the geometric equinox sunrise can be shown to be less than 90º (north of due east in the northern hemisphere). The magnitude of the difference depends on the observer’s latitude and the apparent diameter of the Sun (see figure 2). From figure 2 it is apparent that the only location where the equinox sunrise occurs exactly at the east point is on the equator. ”
We note that, while the failure of this prediction to meet reality is acknowledged, and remarks to the nature of 'only at the equator' are given, no observations of the sun at the equator are referenced.
Myth II: Equal Day and Night
It is claimed that this day is a special day which receives equal day and night. The very name equinox, indeed, means 'equal day and night'.
“ During the equinoxes (March 21 and September 21), a day lasts 12 hours and a night lasts 12 hours at all latitudes. ”
Approximate Date of "Equal Day and Night"
Ancient Observatories - Timeless Knowledge
by Deborah Scherrer, Stanford Solar Center
Link to Paper
In 2015 Deborah Scherrer of the Standford Solar Center provided a document titled "Ancient Observatories - Timeless Knowledge." On page 39 we see the following:
“ Calculating the Equinoxes
Most dictionaries erroneously define the equinox as: “the time or date (twice each year) at which the Sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20)”. However, there is no place on Earth where the day and night are of equal length on the given days.
Latitude Determines Day Length
In fact, latitude determines day length. Even if day and night aren’t exactly equal on the day of the equinox, there are days when day and night are both very close to 12 hours. However, this date depends on the location’s latitude, and can vary by as much as several weeks. The table shows approximate dates for when day and night are as similar as possible according to latitude. ”
Like with so much else in the model, the refraction argument is used as a sweeping rebuttal to anyone who sees the sun for longer than it should be, shorter than it should be, or as a rebuttal to anyone who sees it rise from a location where it should not rise from. The Round Earth Theory is unable to be justified with a prediction that fits reality.