Haven, although commonly referred to as a planet, was in fact a marginally habitable moon of a gas giant called the Cat's Eye which orbited Byers’ Star. It was located at the edge of the CoDominium expansion and was used as a dumping ground for both criminals and political prisoners. Travel time from Earth was approximately one year.
Haven had a very thin atmosphere and even at sea level it was equivalent to 10,000 feet on Earth. In addition, its distance from it's star made it's average temperature much lower than that of Earth.
Geographically, it had one major continent which straddled the moon's equator. Coincidentally, the continent had a massive valley also centered on the equator. This meant that Shangri-La Valley had both the highest air pressure and mildest temperatures on the moon. This valley was the first area settled, first by the Church of New Universal Harmony which bought the colonization licence and later by miners and by deportees. Settlement spread to the vast steppe to the north of the valley and to smaller valleys such as Tallinn and Eden.
Because Haven was a moon, it had a more complicated day / night cycle than a planet. It was close enough to Cat's Eye to receive significant reflected light from the planet although not as much as from Byer's Star. The cycle would begin with truenight where both Cat's Eye and Byer's were below the horizon. The moon's rotation with respect to the star was almost 87 hours while with respect to it's planet was just under 132 hours. Therefore, at times just Cat's Eye would be above the horizon giving dimday. At others, Byer's would be, giving trueday. At still others both would be creating an extra bright trueday.