# Stabilizing the Temperature On a Planet With a (Very) Long Day

Let's say my terrestrial planet has a stable circumbinary orbit around two suns similar to the Kepler-47 system, in the habitable zone, with an orbit similar to Kepler-47c. The challenge here is that I'm trying to set it up similarly to Venus, with a retrograde rotation (probably from an ancient catastrophic collision that created my planet's moon) that takes 340 Earth days to complete. That means approximately 170 days from sun(s)up to sun(s)down.

The trouble is attempting to equalize the temperature. I'd prefer to keep the temperature between 75ºC and -100ºC ... preferably a little less extreme. In real life, Venus's temperature is the same everywhere thanks to its incredibly dense atmosphere. Is there a way I can distribute the temperature?

From what I understand, a high amount of water should help retain the temperature, and the temperature difference itself ought to create powerful storms and winds, which will, again, distribute the heat. And I think a high albedo might stop some heat (though that didn't work out too well for Venus), but I'm not sure what to do about the cold. What else can I do mitigate the temperature effects of such a long day? I've also heard that a slow-rotating planet will have a cooler equator and warmer poles... is that true?

If it's not possible to stabilize the climate somewhat, just let me know.

One more thing… I'm only mostly hopeless okay at math. If someone could direct me to the equations necessary to work all of this out myself (or an online resource for it), I would be very appreciative.

## 1 Answer

Give your planet a mega-ocean. Water is a great heat transfer mechanism. On Earth, we have currents that run from equator to pole, and significantly warm places like the UK.

If you created a world with many small islands you could have an almost earth-like setup but a very slow period of rotation. Your currents will most likely go east-west rather than north-south.

You should expect major storms as well. The light side will experience lots of evaporation, which will result in clouds that travel towards the dark side and then precipitate out. This will transfer additional heat from light to dark side.

• Excellent, thank you. My world is almost entirely an archipelago-scape and the cultures I've built are dedicated to surviving intense storms. I'll keep that in mind! – Midwinter Sun Oct 2 '15 at 23:53