Archaeoastronomy

 

What follows are my notes studying astronomical orientations & alignments as they pertain to megalithic sites and monuments, i.e. Archaeoastronomy. The purpose is for inspiration in the creation of gaming related resources such as:

  • Maps for structures and sites
  • Motivations for Cults of various typical D&D inspired alignments
  • Events within games
  • Inspiration for the creations of story elements. Example: prophesies
  • Puzzles and Mysteries
  • Background information to give “more life” to a gaming world

This is not an exhaustive resource on this topic. Where appropriate, I am significantly simplifying elements to “get to the point”. I’m not NASA nor a rocket scientist, I’m just a lowly Dungeon Master.

Modern Cosmology vs. The Manual of the Planes vs. Spelljammer

First off, all of this research (obviously) only applies if you are using an analogous “real world” Earth cosmology within your game. That is to say, the equivalent of a 365.25 day solar cycle, one major moon, and stellar constellations which go through a procession. This is the base assumption within the Spelljammer box set BTW. I may do more research on Spelljammer and insert updates here. Regarding The Planes, I like to refer to the Far Realm (Based on Lovecraftian references, introduced in AD&D 2e, formalized into the cosmology of the edition which will go unnamed, and remains in D&D 5e) but this has no “real” celestial origin.

Does it Matter if Your World Rotates Around the Sun?

For all practical purposes of these alignments, I don’t think it does. Since we are keeping all of this simple, I believe the end result is the same. I will assume a standard model here, but for any “flat earth” type of fantasy world, the same celestial movements can be applied (in which case, you may want to severely limit any motion by players to research a telescope in game!).

Does it Matter if You have a “Leap Year”?

No. To keep it simple, this can be ignored, but any calculations below assume Earth’s solar cycle.

The Sun

Since the Earth rotates around the Sun on a tittle rotational axis, the amount of daylight incrementally varies on a daily basis and produces 4 defined Solar events.

Note: Keep in mind that each definition assumes a location in the Northern Hemisphere of the planet. Each event is “reversed” if the observer is located in the Southern Hemisphere.

EQUINOX

Equinox

In simplistic terms, Equinox refers to the two days of the year when daytime and nighttime are of equal durations.

The Vernal Equinox refers to the day in the Spring that daytime = nighttime and marks the “first day” of Spring in most cultures.

The Autumnal Equinox refers to the day in the Autumn that daytime = nighttime and marks the “first day” of Autumn in most cultures.

Solstice

In the simplest terms, Solstice refers to the two days of the year of either the longest or shortest daylight (and hence the shortest or longest night). In addition, the Solstice marks the day of most Northerly or Southerly procession of the Sun across the sky during the year. Solstice is historically of more importance from an occult perspective.

Note: Keep in mind that each definition assumes a location in the Northern Hemisphere of the planet. Each event is “reversed” if the observer is located in the Southern Hemisphere.

Summer Solstice marks the date of the longest day, or in other words, the longest amount of daylight.

Winter Solstice marks the date of the longest night, or in other words, the smallest amount of daylight.

Other Basic Terms

Meridian: The path which the Sun takes across the sky.

Zenith: Noon. The time of highest point in the sky for the sun across it’s Meridian during the day.

SOLAR ECLIPSES

Straight from Wikipedia: A solar eclipse (as seen from the planet Earth) is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and when the Moon fully or partially blocks (“occults“) the Sun. This can happen only at new moon when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon.

Frequency of Solar Eclipses

Although, on average, a total solar eclipse occurs somewhere on the Earth once every ~18 months, the frequency of eclipses at one exact location is rare. I can’t find a straight answer on this. The best I have right now is “it is estimated that they recur at any given place only once every 360 to 410 years, on average.”

The Moon

 

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