- #1
shelanachium
- 41
- 0
I have been toying with an SF scenario in which an Earth-like planet has a synchronous moon. Among the consequences are regular eclipses every spring and autumn, poor visibility of the stars on the side facing the moon except during eclipses, and no need for chronometers to determine your longitude on the side facing the moon (and perhaps a great reluctance among sailors to visit the averted side).
However I have read that such systems are not stable unless the moon has 10% or more of the mass of its planet, so I'd have to make my moon as big as Mars. Is this true?
What are the conditions for stability of a mutually synchronous pair of bodies in the gravitational field of a star?
And also, suppose the Moon were a twin of Earth. How far away could it be without escaping into its own orbit? (and probably ending up colliding with Earth - end of story with a very big bang!)
However I have read that such systems are not stable unless the moon has 10% or more of the mass of its planet, so I'd have to make my moon as big as Mars. Is this true?
What are the conditions for stability of a mutually synchronous pair of bodies in the gravitational field of a star?
And also, suppose the Moon were a twin of Earth. How far away could it be without escaping into its own orbit? (and probably ending up colliding with Earth - end of story with a very big bang!)