Moons of Sânat

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Sânat is orbited by four moons, a large, primary moon, the two small moons in associated orbits to the primary, and a tiny moonlet much further out.

The Primary Moon

Trade Tongue: http://www.sedesdraconis.com/images/letters/kedan/7eza.gif ("7eza")

The primary moon, 7eza, resembles the moon of Earth. It is approximately 1.07 times as massive (7.8 * 1022 kg), and orbits slightly (about 15%) farther away from Sânat, then Luna does from Earth. It appears slightly smaller in the sky than Luna from Earth; its apparent angular size* of .48°.

((*Angular Size, the amount of space an object takes up in the sky, being the angle between the lines of sight of its two opposite side.
For comparison, seen from Earth, Luna has angular size of .52° and Sol appears to occupy .53°.))

7eza completes a full orbit every 32.729 days. In conjunction with Sânat' movement around its sun, this give the moon a lunar cycle (full moon to full moon) of 36.336 days.

The Secondary Moons

Trade Tongue:

http://www.sedesdraconis.com/images/letters/kedan/kedo.gif ("Kedo") and http://www.sedesdraconis.com/images/letters/kedan/ashena.gif ("Ashena")

The secondary moons of Sânat, Kedo and Ashena, are much smaller, 9.3 * 1020 kg and 9.1 * 1020 kg, respectively, (about 1.2% the mass of the primary moon). The secondary moons have angular sizes of .12° and .11°.

The secondary moons occupy the stable orbit point known as trojan point orbit (or the L-4 and L-5 positions). This means that each of the secondary moons maintain a position relative to Sânat and the primary moon such that they are the points of equilateral triangles that have a base that is the line running from Sânat to the primary moon (see the diagram, below).

This means each secondary moon orbits Sânat at the same distance and the same rate as the primary moon, but one-sixth of an orbit ahead and behind. This means also that the two secondary moons are one-sixth of a circle ahead and behind the primary moon in the sky as seen from Sânat. Because of this the secondary moons are distinguished as the "leading" (Kedo) and "lagging" (Ashena) moons.

It should be noted that the leading moon, which is one-sixth of a day ahead of the primary moon (in the daily cycle of rising and setting) is one-sixth of a lunar cycle behind the primary moon, and the lagging moon is the other way around. That is Kedo, called "leading", is actually farther behind the others in it's orbit, but as the planet rotates "under" them, a given point on the planet will catch up with Kedo first, and so it will appear to rise sooner.

So if the 7eza is full and directly overhead, then Kedo will be a waxing gibbous (to be full in about six more nights) that is on it's way down (and was at zenith one-sixth of a day, or two marks, previously). Ashena will be the opposite, a waning gibbous still rising.


http://www.sedesdraconis.com/images/charts/moons.jpg Diagram is not to scale.

The moons are labeled:

"MoonPr" for the primary moon.
"MoonLe" for the leading secondary moon.
"MoonLa" for the lagging secondary moon.

Points around the outer circle of Sânat in the diagram show sky positions of the moons:

"RPr", where the primary moon is rising
"ZPr", where the primary moon is at zenith (directly overhead)
"SPr", where the primary moon is setting
"RLe", where the leading moon is rising
"RLa", where the lagging moon is rising
etc...

The inside shows relative marks. That is, since ZPr is at +0 marks and ZLa is at +2 marks, the lagging moon is at zenith two marks after the primary moon.

The spacing of lunar events through the day is the origin of the time system of dividing the day into twelve parts.

The Outer Moon

Trade Tongue: http://www.sedesdraconis.com/images/letters/kedan/beson.gif ("Beson")

Beson is a small moonlet in a highly elliptical orbit around Sânat at an average distance of 970,000 km. It has a neglible angular size, appearing as a single point of light, like a rather bright star (apparent visual magnitude -1±0.5). It is only mildly noticable in the Sânat's sky, indeed, it is less noticable than many of the other planets in the system. It has a synodic period of 149.65 days.

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