steorran_worulde | Entries tagged with w: earth

A raindrop grows in a cloud. When it's full-formed, it falls. This rainstorm doesn't come with wind, so it drops straight down. It hits a maple leaf in the crest of a tree and slides off. It falls through the tree and lands on the wet trunk - its neighbours have already arrived. It melds into the flow running down the trunk. When it reaches the ground, it soaks into the earth. Slowly, slowly now, it creeps along between the grains of dirt. Seasons pass until one day it oozes out of the earth into a little stream running down a hillside. It rushes and tumbles down the hill, until it comes to the bottom of the hill and joins a bigger stream quietly making its steady way along the bottom of the valley. It flows under water striders and over spawning salmon. After a while, it runs into a great river. The river is muddy with all that it has picked up from its bed and the beds of all the streams that have joined it over the space of many miles. It flows on, not too much farther, until it reaches the sea, and mingles its mud with the ocean's salt. The drop has come home.

I've been thinking about what the fundamental units of the Venus-based calendar I was sketching should be called. The calendar has 5 fundamental units, of the following lengths:
1 day
73 days
365 days (5*73)
584 days (8*73)
2920 days (40*73; 8*365; 5*584)

Some of these units are easy to name, and others are harder. The obvious ones are:
1 day: day
365 days: year

Not entirely obvious, but still easy to name, is:
73 days: season ("month" would be another possibility, but 73 days/5 per year seems more like a season than like a month; it'd be rather long for a month).

This leaves two harder-to-name units.
I have no idea what to call the Venus-synodic-period-length unit of 584 days. A noun derived from "Venus" or another name of Venus might be a possibility, but I don't want to just call it "a Venus", because that's clumsy.

The long unit of 2920 days is decade-scale in length, but decade is obviously not a good name for it, since it isn't 10 of anything long. The idea of "decade" brought to mind a possibility of using something like "octade" or "octad" to signify that it contains 8 years; that's naming it with 8 according to years but ignoring the fact that it contains 5 Venus cycles. Alternatively, I thought of naming it after the pentagram shape traced by the 5 successive inferior conjunctions, and calling it something like a pentagram or a pentangle or just a pent, but that doesn't quite feel right.

And then, while writing this up, I discovered that there is in fact a term for an 8-year cycle: octaeteris (pl. octaeterides). I think for now I'm going to adopt that term. So that just leaves the Venus cycle nameless.

EDIT, the same day:
I think for now I'll designate the Venus cycle a "circuit [of Venus]"; "circuit" suggests the idea of the planet running its course, and is general enough that can mean its course around the sky relative to the sun as seen from Earth, as opposed to, say, "orbit", which I think is inextricably linked to the planet's sidereal year.

So now I have the following units:
Day: 1 day
Season: 73 days
Year: 365 days
Circuit: 584 days
Octaeteris: 2920 days

This is a calendar concept sketch that could go either with Earth or with Domil, since Domil is astronomically equivalent to Earth. Chances are that if it sticks to anything outside itself, it'll get assigned to some Domil culture, but it might just stay on its own without getting integrated into anything larger.

So I was thinking about the coincidental neat relationship between the length of Earth's year and the length of Venus's synodic period relative to Earth and Sun.

It takes about 365.25 days for Earth to return to the same place relative to the sun and the surrounding stars. (1 earth year.)

It takes about 583.9 days for Venus to return to the same place relative to the Earth and the Sun (for instance, from one inferior conjunction to another). (1 Venus synodic period.)

If we round each of those to the nearest integer, we get:
365 days * 8 = 2920 days
584 days * 5 = 2920 days

So basically, every 8 years, Earth, Venus, the Sun, and the stars are all in alignment; or, equivalently, Earth's back at the same time of year, and Venus is back in the same configuration with Earth.

If you connect the dots between the inferior conjunctions of the 5 synodic periods that go into this 8-year cycle, it makes a pentagram shape. Each point of the pentagram marks a different time of year that a inferior conjunction can happen at; the spaces between them basically divide the year into 5 equal segments.

So what happens if we divide 365 days into 5 seasons of equal length?
365 days / 5 = 73 days (Isn't that a beautiful nother coincidence? There's no reason the number of days in the (nominal) year had to be divisible by 5, but it is.)

5 seasons of 73 days each make up a 365-day year.
But also, 8 seasons of 73 days each make up a Venus synodic period:
73 days * 8 = 584 days.

That makes a nice basis for a calendar.
( This gets long. )

S	M	T	W	T	F	S
1	2	3	4	5	6	7
8	9	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30

Steorran worulde

Entries tagged with w: earth

A raindrop's journey

Venus calendar: unit names

Venus synodic calendar

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November 2020

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