You
need to figure out your planet's year length as it relates to the
earth year.
If
your planet's year is in earth days right now
(Example: My planet's
year is 112 earth days long) you need to do this:
|
My
Planet's year in earth days =
365
|
112
365 |
=
.3068493 |
Throw
away most of those decimal numbers: your planet's year = .3
earth years
(about a third of an earth year.
That makes sense)
However,
if you already have a number that is about earth years
(Example: My planet's year is 4.7 earth years long) then
use that number as it is.
Use
Kepler's formula:
|
This is the Formula |
|
(this planet's year in earth years) x
(this planet's year in earth years) |
= |
(distance from sun in AUs) x
(distance from sun in AUs) x
(distance from sun in AUs)
|
squares
of the sidereal periods |
= |
cubes
of their semimajor axes |
|
(sidereal
periods)2 |
= |
(semimajor
axes)3 |