My previous question ruled out having a moon orbiting a gas giant. I've got an interesting ecosystem (my bad, biome was the wrong word) that evolved based upon the idea that the world is eclipsed for a 6 month period and enters a deep ice age once every couple of years. Is there anything that could cause such a situation?
Perhaps an asteroid belt so thick it darkens the planet as the planet orbits beyond the belt passing above then below the plane of the belt? Is that kind of orbit possible?
Per Morris suggestion below, if the planet orbited a dim binary, could I forego the gas giant entirely? Can a star be so dim that having it come between the planet and the brighter star be like nightfall?