Celestia Forums

Ok, so on my gaming system, I have a few friends interested.

To test myself in the use of Celestia, I gave them the options of creating a world, that would orbit around a common sun. In this case, our sun, just so I could have it easy.

One of the members has created a world, with these details.

Planet: Lunesia
Rotation (the length of a day) - 76 hours
Year Length - 730 days
Day: 6 hours
Night: 70 hours

Moon: Arc
Rises at the 6 hour mark and is present the full 70 hours of night.

Moon: Resia
Rises at the 12 hour mark and is present for 64 hours of night.

My brain is melting trying to arrange this. Needless to say, I'm a novice to this program. So I'm issuing a plea for help. But I do have some ideas I managed to pull out of the puddle leaking from my ears.

1) If I just stick the planet it and put it's rotation at 76 hours, it is likely going to be 38 hours sunlight, 38 hours night. So that isn't gonna work.

I was thinking though, what if I put the orbit of Lunesia as something like an oval, rather than a perfect sphere. And then Lunesia can be set to orbit along this oval for 730 days to make one complete pass. That would solve the first part. Now to have 6 hours of light and 70 hours of darkness, for it's rotation. Maybe a planet to eclipse things, something like how it worked in the movie Pitch Black, but rather than it happening every so many years, it'd have to occur every day.

Is this possible at all, or am I melting my brain over it for nothing?

Either your friend is intentionally yanking your chain, or he doesn't understand how planetary systems actually work. However, if the light and dark durations don't have to stay the same, then day and night will be of different lengths at different latitudes during different seasons if the planet has a tilted axis -- like happens on the Earth. Similarly, the moons can rise and set as specified on particular dates, but not always.

Yeah. I know how it's dark longer in the polar areas on Earth, due to the tilt.

Thanks for the help Selden, I'll let them know that it can't be done. I'm pretty sure it was the second option, that she didn't fully understand how things worked.

Well, if you want to create imaginary worlds, with physically impossible rotations, you could consider writing a ScriptedRotation. They could turn fast for a while and then more slowly, so the periods of light and dark could change.

Eclipsing behind a larger planet can be used to vary the amount of light and dark, too, but that isn't the same as having different length days and nights.