Tag Archives: day-night

Binary star systems

Since starting to write the Suns of Vokhtah series again, I’ve tripped up on some unexpected hurdles, one of which is the effect the binary star system has on the day/night and seasonal changes as experienced on the planet.

I thought I’d worked it all out over five years ago, and I do have graphics to prove it, but as I looked at those graphics I realised that I couldn’t remember the thinking behind them:

Was it actually right? I no longer knew. And it niggled so much I knew I had to go back and reinvent the wheel. So these are the earliest of the new graphics:

Creating the day/night cycle in Corel Draw 8 stage 1:

As you can see, the planet obits the G2 [yellow] star in an elliptical orbit which makes EVERYTHING so much harder. The lines connecting the centre of the star to the centre of the planet are always at right angles to simulate the orientation of the planet to its star. Assuming the star and planet exist on a flat plane, I think that’s right, from the point of view of geometry. Seems logical, but I know very little about actual astronomy.

Anyway, the big yellow star is Takh and the small red one is its binary companion, Takhti.

Next step in Corel was to group the positions of the planet, and flip a copy of them horizontally. A bit of realignment was necessary to get it looking like this:

And finally, I filled in the gaps at the top and bottom:

I haven’t modelled the effect of the dwarf red star yet, so it’s hard to see the significance of the example at the very bottom, but mid-Piihoh is the time in the planetary cycle when the dwarf red sun is completely eclipsed by the G2 star.

The example at the very top is mid-Kohoh. This is when the planet experiences virtually no dark – i.e. night time. Again, this will become more obvious once I complete the red dwarf overlays. Of course, working /that/ out requires some hefty mental shifts on my part because the planet rotates in an easterly direction around its own axis, but revolves around the G2 sun in an anti-clockwise direction…

Nevermind, I sort of know what I’m doing, but it still gives me brain-ache.











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