[Dragaera] Dragaera and Moons **Minor Vallista Spoiler, nothing plot related**

[Konrad Gaertner]

On 11/2/2017 10:19 PM, Jon via Dragaera wrote:
> Spoiler Space
> 
> 1
> 
> 2
> 
> 3
> 
> 4
> 
> 5
> 
> 6
> 
> 7
> 
> 8
> 
> 9
> 
> 10
> 
> 11
> 
> 12
> 
> 13
> 
> 14
> 
> 15
> 
> 16
> 
> 17
> 
> Littlemoon, however, has the characteristic of not rising and falling 
> every day--indeed, we are told it will be at least nine days before it 
> will rise again.
> 
> A basic understanding of orbital mechanics reveals a few interesting 
> things about this circumstance. Firstly, this means that the orbital 
> period of this moon above the planet must be in fairly close proximity 
> to the rotational period of the planet itself. Effectively, it means 
> this moon must orbit at a point close to (but not exactly at) the 
> natural altitude for a fully geosynchronous orbit. It cannot diverge 
> from this orbital period by more than about 2 hours per day (given 
> Dragaera's 30-hour day), however, or else it would always take fewer 
> than nine days to appear again in the sky at any particular point on the 
> surface of the planet.

Is this the only option using normal physics? I'm asking because in
another series I'm reading, there's a world with a moon that is similar
in size and phases to Earth's, but is only visible every eighth day.

(The series is Andrea K. Host's Touchstone, which isn't much like
Brust's work except for being first-person and having some similar
worldbuilding.)


-- 
Konrad Gaertner - - - - - - - - - - - - email: kgaertner at tx.rr.com
https://kgbooklog.dreamwidth.org/
"I don't mind hidden depths but I insist that there be a surface."
                           -- James Nicoll

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus