I realise this a double post, but I've done the maths and have come up with some interesting conclusions. I believe it's already established that Akana is the same mass as the Earth and receives roughly the same amount of heat from its sun. It is definitely established that the solar year is 384.1 days long and the month is 44.96 days.
First off, we can make the day as long or as short as we want within reason, but I've decided on two basic starting points: an Akanaran synodic day the same length as ours, or an Akanaran year the same length as ours. (
Synodic is the motion or period relative to the sun, while
sidereal is the motion or period relative to the "fixed stars".) All of these calculations assume circular orbits - I can account for eccentricity if we want, though.
With an Akanaran synodic day the same as ours, at 24 hours:
- The year is about 5% longer than ours.
- To receive the same amount of solar radiation, Akana will orbit a G1 star marginally brighter and hotter than ours. Its orbital distance is 1.047 AU, and the apparent diameter of the sun is about 3% less.
- The moon orbits at a distance of 496150 km to keep the synodic month the right length.
With an Akanaran year the same length as ours:
- The synodic day is about 5% shorter than ours, at 22 hours 49 minutes 21 seconds (to the nearest second).
- The moon orbits at 479787 km.
Either way some things are apparent about the moon.
- In order to cause total eclipses, the moon must be 4497 km across (4466 km for the latter case) at a
bare minimum, probably more like 5000 km. This puts it in the league of Solar System objects like Callisto (4820 km), Mercury (4879 km), Titan (5152 km), and Ganymede (5262 km).
- If we went for an example of 5000 km diameter, and a density of 3300 g/cc like our own moon, it would have a mass of 0.036 times the Earth (or Akana), very close to three times the mass of our moon. (Yes, Callisto, Titan, and Ganymede are much less dense, but they're icy. Mercury is much more dense because it's largely iron. I think Earth's Moon, Io, and possibly Europa and Mars are better models for a mostly rocky body, indicating a density between 3000 and 4000 g/cc.)
- Tidal forces would be strong. This is mitigated by the greater distance to the moon (inverse squares means that the relative strength of gravitational attraction compared to our Earth-Moon system is 60% for the first scenario and 64% for the second). However, even in the first scenario and with a 0.036 Earth-mass moon, tidal forces would be 80% greater than those exerted on Earth by our Moon.
It's a cool scenario, but noticeably different from Earth...
And on the planets, there are some interesting possibilities:
- Large inner-system planets, by which I mean "hot Neptunes/Jupiters/super-earths". Apparently these can form in a system with Earth-like planets. The upshot would be one or more very bright "evening/morning stars" like Venus but more so, and a greater opportunity for astronomers to study transits, phases of planets, and so on.
- Orbital resonances of visible planets. These are just really cool all round, allowing for planets that show up in highly predictable places and intervals, ripe for symbolic interpretation.
- I also note that Tsinakan was, at least by the third century,
identified with a predictable 43-year comet. I wonder what non-Ndok make of it...
Holy crap!
